BSR/IIAR 2-201x Standard for Safe Design of Closed-Circuit Ammonia Refrigeration Systems November 14, 2014 Public Review #3 Draft

Transcription

1 BSR/IIAR 2-201x Standard for Safe Design of Closed-Circuit Ammonia Refrigeration Systems November 14, 2014 Public Review #3 Draft R1

2 Notes on the Standard Text Metric Policy The IIAR metric policy for ANSI standards, bulletins and all IIAR publications is to use the common engineering inch-pound (IP) unit system as the primary unit of measure, and the International System of Units (SI), as defined in United States National Institute of Standards and Technology Special Publication 330 The International System of Units, for secondary units. Normative/Informative Elements This standard includes normative (required) provisions. The Foreword and Appendices are nonmandatory. Informative material shall never be regarded as a requirement. Notice The information contained in this Standard has been obtained from sources believed to be reliable. However, it shall not be assumed that all acceptable methods or procedures are contained in this document, or that additional measures may not be required under certain circumstances or conditions. The Standards Committee and Consensus Body that approved the Standard were balanced to assure that individuals from competent and concerned interests have had an opportunity to participate. The proposed Standard was made available for review and comment for additional input from industry, academia, regulatory agencies and others. The IIAR makes no warranty or representation and assumes no liability or responsibility in connection with the use of any information contained in this document. Use of and reference to this document by private industry, government agencies and others is intended to be voluntary and not binding unless and until its use is mandated by authorities having jurisdiction. The IIAR does not approve or endorse any products, services or methods. This document shall not be used or referenced in any way which would imply such approval or endorsement. Note that the various codes and regulations referenced in this document may be amended from time to time and the versions referenced herein are the versions of such codes and regulations set forth in Chapter 3 of this Standard. The IIAR uses its best efforts to promulgate Standards for the benefit of the public in light of available information and accepted industry practices. However, the IIAR does not guarantee, certify, or assume the safety or performance of any products, equipment or systems tested, installed, or operated in accordance with IIAR s Standards or that any tests conducted under its Standards will be nonhazardous or free from risk. This Standard is subject to periodic review. Up-to-date information about the status of the Standard is available by contacting IIAR.

3 Copyright This document may not, in whole or in part, be reproduced, copied or disseminated, entered into or stored in a computer database or retrieval system, or otherwise utilized without the prior written consent of the IIAR. Copyright 2014 by INTERNATIONAL INSTITUTE OF AMMONIA REFRIGERATION All Rights Reserved

4 Foreword (Informative) This document is a standard for the safe design of closed-circuit ammonia refrigeration systems. The safety focus is on persons and property located at or near the premises where the refrigeration systems are located. Additional precautions may be necessary because of particular circumstances, project specifications or other jurisdictional considerations. This standard is not intended to serve as a comprehensive technical design manual and shall not be used as such. Experience shows that ammonia is very stable under normal conditions and rarely ignites when a release occurs because the flammability range in air is narrow and the minimum flammable concentration in air is very high as compared to other ignitable gases. Ammonia has a published flammability range of 160,000 ppm to 250,000 ppm. This concentration far exceeds ammonia s odor detection threshold and the 50 ppm permissible exposure limit (PEL) published by OSHA. Ammonia s strong odor alerts those nearby to its presence at levels well below those that present either flammability or health hazards. This self-alarming odor is so strong that a person is unlikely to voluntarily remain in an area where ammonia concentrations are hazardous. The principal hazard to persons is ammonia vapor, since exposure occurs more readily by inhalation than by other routes. As with any hazardous vapor, adequate ventilation will dilute the vapor and greatly reduce exposure risk. Ammonia in vapor form is lighter than air. Typically, ammonia vapor rises and diffuses simultaneously when released into the atmosphere. It is biodegradable, and when released, it combines readily with water and/or carbon dioxide to form relatively harmless compounds. Ammonia may also neutralize acidic pollutants in the atmosphere. Additional information regarding the properties of ammonia is published in the IIAR Ammonia Data Book. This standard was first issued in March of 1974 by the International Institute of Ammonia Refrigeration (IIAR) as IIAR The standard was first approved as an American National Standard by the American National Standards Institute (ANSI) in March 1978 as ANSI/IIAR A revision of the standard, ANSI/IIAR was approved by ANSI in July 1985, as were subsequent revisions in December 1992, August 1999, October 2005, June 2008, August 2010, and December, This standard was prepared using the ANSI Consensus Method; whereby, organizations and individuals recognized as having interest in the subject of the standard were contacted prior to the approval of this revision for participation on the Consensus Body and in public reviews. The standard was prepared and approved for submittal to ANSI by the IIAR Standards Committee and the IIAR Board of Directors. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page i

5 BSR/IIAR 2-20XX: Changes for this new edition IIAR 2 has undergone extensive revision since the 2008 (with Addendum B) edition, published December 3, Some of the more significant revisions are highlighted here to assist users of this document. A major focus of changes made to the 2014 edition has been incorporating topics traditionally addressed in other codes and standards so that IIAR 2 can eventually serve as a single, comprehensive standard covering safe design of closed-circuit ammonia refrigeration systems. As part of the update process, a gap analysis was performed that compared information in IIAR 2, ASHRAE Standard 15 - Safety Standard for Refrigeration Systems, the Uniform Mechanical Code, the NFPA 1 Fire Code, the International Mechanical Code and the International Fire Code. Where differences were identified, the IIAR 2 rewrite drafting committee either included or revised the information in this standard, or determined that the information was not necessary to meet minimum safe design standards for ammonia refrigeration systems. In addition to the changes brought about by the gap analysis, this standard has been revised to clarify provisions that previously existed in IIAR 2. In some cases, information previously included in IIAR 2 was deemed unnecessary and was deleted from the 2014 edition. Additionally, new provisions not previously addressed by any code or standard have been added based on public proposals or at the recommendation of the rewrite drafting committee. Some of the major changes to the 2014 edition of IIAR 2 are summarized in the following paragraphs. However, users of this standard are cautioned that there are many other revisions that can only be identified and understood by reviewing the standard in its entirety. It should be noted that the title of the standard has been changed. The new title attempts to convey that the scope of IIAR 2 has been expanded to include safety topics that were previously unaddressed by the standard. In addition, the standard is now organized into Parts and Chapters. There are four Parts: Part 1 - General, includes Chapter 1 through Chapter 3. Part 2 - Design and Installation Considerations Affecting Construction, includes Chapter 4 through Chapter 7. Part 3 - Equipment includes Chapter 8 through Chapter 17. Part 4 - Appendices includes Appendix A through Appendix N. The Chapter numbers remain sequential, and the four Parts are simply provided as an aid for users in understanding the layout of chapters in the standard. Chapter 1 General, includes sections on Purpose, Scope, and Applicability. The scope now clarifies that the standard applies only to stationary closed circuit refrigeration systems. Chapter 2 Definitions, has fewer definitions than were included in previous editions. Definitions that appeared in previous editions that were not changed have been relocated to IIAR 1, Definitions and Terminology Used in IIAR Standards. New or revised definitions applicable to this standard are included in Chapter 2. It is intended that, once this standard has been published, definitions for these new terms will also be relocated to IIAR 1 in a future update. Chapter 3 Reference Standards, includes numerous reference standards that have been updated. References included in Chapter 3 are now limited to those that are mandatory for compliance with this standard. Informative references are now in Appendix N. Chapter 4 Location and Use of Ammonia Refrigeration Machinery, is new. This chapter includes restrictions on the use of ammonia refrigeration systems, as applicable, based on the occupancy classification of the area where the system or equipment will be located. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page ii

6 Chapter 5 System Design, largely retains information that was included in previous editions. Notable changes include a revision when selecting system design pressures. Requirements that apply to selecting system design pressures were provided. The minimum low-side and high-side design pressure is 250 psig; however, individual pieces of equipment might require higher design pressures. Requirements for the removal of oil from oil pots have been changed such that there is no longer a requirement to temporarily install a rigid-piped connection. Direction for the provision of maintenance and functional testing was added. Information on field leak tests has been removed, and a reference to IIAR 5 was added in its place. Minimum valve tagging standards for system emergency shut-down procedures have been added, as well as a section on equipment enclosures. Chapter 6 Machinery Rooms, largely retains information that was included in previous editions. Notable changes have been made to alarm and detection requirements. Ventilation requirements have been modified and ventilation alternatives have been added. A section on ventilation requirements for systems located outdoors, which are sometimes partially or fully enclosed, has been added, as has a section regulating site considerations. Changes have been made to the requirements for eyewash/safety showers to harmonize the standard with OSHA and ANSI/ISEA requirements. Also, there is a new allowance for machinery rooms that do not exceed 500 square feet in floor area to not require a direct means of egress to the outside, which will accommodate small machinery rooms supporting process equipment to be located close to that equipment. Chapter 7 Areas Other than Machinery Rooms, is new material. Previously, regulations concerning certain types of refrigeration equipment located in areas other than machinery rooms have not been provided. For example, in industrial occupancies, it is often necessary to have evaporators located outside of a machinery room in storage and production areas. This chapter provides minimum safety requirements for locating refrigeration equipment in areas other than machinery rooms, but only where allowed by Chapter 4. Chapters in Part 3 Equipment, primarily cover major equipment categories, with one chapter for each category. Most of the information has been retained from previous editions. Chapter 8 Compressors, includes a notable change specifying a ¾-inch minimum size for relief connections. Chapter 9 Refrigerant Pumps, provides requirements for refrigerant pumps, which are different from those that are specified for compressors. Chapter 10 Condensers, includes a significant change establishing that the minimum design pressure for condensers is now 250 psig. This is consistent with the minimum design pressure requirement for all high-side equipment. However, higher pressure might be required based on environmental conditions. Chapter 11 Evaporators, includes a significant change establishing that the minimum design pressure for evaporators is now 250 psig, or alternatively, the high-side design pressure if hot gas is used to defrost the evaporator. New sections on scraped (swept) surface heat exchangers and jacketed tanks have been added. Chapter 12 Pressure Vessels, provides minimum design pressure requirements that are consistent with those described above. In addition, like Chapter 8, the chapter establishes that the minimum size for a relief connection is ¾-inch for vessels that are over 6 inches in diameter and 1 inch for vessels that are 10 cubic feet or larger. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page iii

7 Chapter 13 Piping, includes requirements for piping, tubing, fittings, flanges, valves and strainers. Chapter 14 Packaged Systems and Equipment, covers a new topic. This chapter was added in recognition of a need for regulations related to pre-assembled systems, subsystems and equipment, which are becoming increasingly common. Chapter 15 Overpressure Protection Devices, is expanded versus previous editions. The chapter includes methods for evaluating and designing for worst-case scenarios to avoid over-pressurizing equipment. Direction regarding pressure relief piping termination has been added to address adjacent roofs in the vicinity of the relief termination. Further, requirements for termination of relief piping above evaporative condensers have been clarified. An option addressing the voluntary use of diffusion tanks has also been included, and requirements for hydrostatic overpressure protection have been clarified. Also, Appendix A of previous editions has been relocated to the body of the standard in Section Given that the prior edition s appendix was normative, compliance was mandatory in all cases, so there was no reason for this material to be in an appendix versus being located in the body of the main standard. As compared to previous editions, provisions for venting have been modified by deleting the single-relief vent line sizing tables. The size of relief vents must now always be calculated using the formula provided. Chapter 16 Instrumentation and Controls, includes clarified requirements for automated controls and their functionality. Chapter 17 Ammonia Detection and Alarms, establishes the requirements for detection and system response functions. This chapter standardizes requirements that have historically varied depending on jurisdiction, designer, contractor, supplier and end-user interpretations. Informative Appendix A has been added to provide explanatory information related to provisions in the standard. Sections of the standard that have associated explanatory information are marked with an asterisk * after the section number, and the associated appendix information is located in Appendix A with a corresponding section number preceded by A. Informative Appendix B has been revised to cover methodologies for calculating relief valve capacity for various heat exchangers. The former Appendix B, Minimum Values of Design Pressure and Leak Test Pressure, has been removed. Design pressure information can now be found in the main body of this standard. Leak pressure information can now be found in IIAR 5, Start-up and Commissioning of Closed-Circuit Ammonia Refrigeration Systems. Information pertaining to insulation found in prior editions of this standard has been relocated to IIAR 4, Installation of Closed-Circuit Ammonia Mechanical Refrigeration Systems. Information pertaining to purging found in prior editions of this standard has been relocated to IIAR 5, Start-up and Commissioning of Closed-Circuit Ammonia Refrigeration Systems. Appendix K provides guidance on calculating ventilation rates for newly-recognized alternative ventilation methods. Appendix L includes guidance information on pipe, fittings, flanges, and bolting that have been commonly used historically in ammonia industrial refrigeration systems. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page iv

8 Appendix M provides guidance on operational containment as an optional but uncommon alternative to the traditional ventilation approach to release incidents. Appendix N includes non-mandatory references, which were relocated out of the main body of the Standard. Appendix N of the previous edition, dealing with guidance related to site considerations, has been deleted. At the time of publication of this edition of the standard, the IIAR Standards Committee included the following members: Robert J. Czarnecki, Chair - Campbell Soup Company Don Faust, Vice Chair - Gartner Refrigeration & Mfg., Inc. Eric Brown - ALTA Refrigeration, Inc. Dennis R. Carroll - Johnson Controls Eric Johnston - ConAgra Foods, Inc. Gregory P. Klidonas - GEA Refrigeration North America, Inc. Thomas A. Leighty - Freije-RSC Brian Marriott - Marriott and Associates Rich Merrill - Retired, EVAPCO, Inc. Ron Worley - Nestlé USA Trevor Hegg - EVAPCO, Inc. Joseph Pillis - Johnson Controls Dave Schaefer - Bassett Mechanical, Inc. Peter Jordan - MDB Risk Management Services, Inc. John Collins - Zero Zone, Inc. The subcommittee responsible for rewriting this standard had the following members at the time of publication: Thomas A. Leighty, Subcommittee Chair Freije-RSC Dave Schaefer, Subcommittee Vice Chair - Bassett Mechanical, Inc. Trevor Hegg - EVAPCO, Inc. Don Faust - Gartner Refrigeration & Mfg., Inc. Peter Jordan - MDB Risk Management Services, Inc. Glen Heron - Tyson Foods, Inc. Eric Johnston - ConAgra Foods, Inc. John Collins - Zero Zone, Inc. Carl Burris - Tyson Foods, Inc. Robert A. Sterling - Sterling Andrews Engineering, P.L. Luke Facemyer - Stellar Eric Smith - IIAR Staff Tony Lundell - IIAR Staff Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page v

9 Contents Notes on the Standard Text... i Metric Policy... i Normative/Informative Elements... i Notice... i BSR/IIAR 2-20XX: Changes for this new edition... ii Contents... vi Part 1 General...1 Chapter 1. Purpose, Scope and Applicability Purpose *Scope Applicability...1 Chapter 2. Definitions General *Defined Terms....2 Chapter 3. Reference Standards American Society of Mechanical Engineers (ASME), American Society of Testing and Materials (ASTM), Compressed Gas Association (CGA), International Institute of Ammonia Refrigeration (IIAR), International Safety Equipment Association (ISEA), National Fire Protection Association (NFPA), Occupational Safety and Health Administration (OSHA), U.S. Department of Labor,...5 Part 2 Design and Installation Considerations Affecting Construction...6 Chapter 4. Location of Ammonia Refrigeration Machinery General *Permissible Equipment Locations....6 Chapter 5. General System Design Requirements General Anhydrous Ammonia Specifications Machinery location *Volume Calculation for Determining Concentration of an Ammonia Release Use of Ammonia Refrigeration with Secondary Coolants....8 Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page vi

10 5.6 *System Design Pressure System Design Temperature Materials *Purging Oil Management Insulation Condensation Control for Piping and Fittings Foundations, Piping, Tubing, and Equipment Supports Service Provisions Testing Signage, Labels, Pipe Marking and Wind Indicators Emergency Shutdown Documentation Equipment Enclosures General Safety Requirements...15 Chapter 6. Machinery Rooms General Construction Access and Egress Combustible Materials Open Flames and Hot Surfaces Piping Eyewash/Safety Shower Electrical Safety Drains Entrances and Exits Lighting Emergency Control Switches Ammonia Detection and Alarm Ventilation Signage Chapter 7. Refrigeration Equipment Located in Areas Other Than Machinery Rooms General Requirements for Non-machinery Room Spaces Ventilation...26 Part 3 Equipment...28 Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page vii

11 Chapter 8. Compressors General Design Pressure Positive-Displacement Compressor Protection Procedures/Testing Equipment Identification Compressor Installation Chapter 9. Refrigerant Pumps General Design Procedures/Testing Equipment Identification Chapter 10. Condensers *General Air-Cooled Condensers and Air-Cooled De-superheaters Evaporative Condensers Shell-and-Tube Condensers Plate Heat Exchanger Condensers Double-Pipe Condensers Chapter 11. Evaporators General Forced-Air Evaporator Coils Shell-and-Tube Evaporators Plate Heat Exchanger Evaporators Scraped (Swept) Surface Heat Exchangers Jacketed Tanks Chapter 12. Pressure Vessels General Design Procedures/Testing Equipment Identification Pressure Vessel Installation Considerations Chapter 13. Piping *General Pipe, Tubing, Fittings, and Flanges...50 Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page viii

12 13.3 *Refrigerant Valves and Strainers *Piping, Hangers, Supports Isolation *Location of Refrigerant Piping...53 Chapter 14. Packaged Systems and Equipment General Design Fabrication Alarms and Detection Chapter 15. Overpressure Protection Devices *General *Pressure Relief Devices Pressure Relief Protection Pressure Relief Device Piping Discharge from Pressure Relief Devices Equipment and Piping Hydrostatic Overpressure Protection...66 Chapter 16. Instrumentation and Controls General Visual Liquid Level Indicators: *Electric and Pneumatic Sensor Controls...69 Chapter 17. Ammonia Detection and Alarms Scope Power for Detectors and Alarms Testing Detector Placement *Alarms Signage Detection and Alarm Levels Part 4 Appendices...72 Appendix A. (Informative) Explanatory Material...72 Appendix B. (Informative) Ammonia Characteristics and Properties...82 Appendix C. (Informative) Methods for Calculating Relief Valve Capacity for Heat Exchanger Internal Loads...84 Appendix D. (Informative) Duplicate Nameplates on Pressure Vessels...92 Appendix E. (Informative) Method for Calculating Discharge Capacity of a Positive Displacement Compressor Pressure Relief Device...93 Appendix F. (Informative) Pipe Hanger Spacing, Hanger Rod Sizing, and Loading...95 Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page ix

13 Appendix G. (Informative) Hydrostatic Overpressure Relief...97 Appendix H. (Informative) Stress Corrosion Cracking Appendix I. (Informative) Emergency Pressure Control Systems Appendix J. (Informative) Machine Room Signs Appendix K. (Informative) Alternative Ventilation Calculation Methods Appendix L. (Informative) Pipe, Fittings, Flanges, and Bolting Appendix M. (Informative) Operational Containment Appendix N. (Informative) References and Sources of References Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page x

14 Part 1 Chapter 1. General Purpose, Scope and Applicability 1.1 Purpose. This standard specifies minimum requirements for the safe design of closed-circuit ammonia refrigeration systems. 1.2 *Scope. Stationary closed-circuit refrigeration systems utilizing ammonia as the refrigerant shall comply with this standard. This standard shall not apply to: 1. Ammonia absorption refrigeration systems. 2. Replacements of machinery, equipment or piping with functionally equivalents. 3. Equipment and systems and the buildings or facilities in which they are installed that existed prior to the legal effective date of this standard. Such equipment, systems and buildings and facilities shall be maintained in accordance with regulations that applied at the time of installation or construction. 1.3 Applicability Conflicts. Where there is a conflict between this standard and the Building Code, Fire Code, Mechanical Code or Electrical Code, the Code requirements shall take precedence over this Standard unless otherwise stated in such Code Alternative Materials and Methods. The AHJ is authorized to approve the use of devices, materials or methods not prescribed by this standard as an alternative means of compliance, provided that any such alternative has been shown to be equivalent in quality, strength, effectiveness, durability and safety *Installations in Locations Without an AHJ. Where a system is installed in a jurisdiction without an AHJ, the designer is authorized to specify an alternative, and the alternative shall be documented in the design documents. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 1

15 Chapter 2. Definitions 2.1 General. Definitions shall be in accordance with this chapter and ANSI/IIAR *Defined Terms. The following words and terms, which are used in this standard, shall be defined as specified in this chapter. AHJ (Authority Having Jurisdiction): The organization, office, or individual responsible for enforcing the requirements of this standard, or for approving equipment, materials, an installation, or a procedure. Authorized Personnel: Persons who have been specifically granted permission to enter a restricted area. Building Code: The building code adopted by the jurisdiction. Building Opening: A permanent or operable area that allows outdoor air into the building envelope including operable doors (e.g. swinging doors, slide doors, roll-up doors, fire doors, access hatches), operable make-up air intakes (where the intakes are not equipped with the ability to close automatically when ammonia is present), and other vents with a permanent opening. Combustible: A material that does not meet the definition of noncombustible material. *Commercial Occupancy: A premises or portion thereof where people transact business, receive personal service, or purchase food or other goods. Double-Indirect Open-Spray System: A system in which the secondary substance for an indirect open spray system is heated or cooled by the secondary coolant from a second enclosure. Electrical Code: The electrical code adopted by the jurisdiction. Equipment: An assembly, subassembly, accessory or component of a refrigeration system. Equipment Enclosure: An enclosure designed to house refrigeration equipment and devices associated with a closed-circuit refrigeration system, or both, that is not intended for occupancy. Fire Code: The fire code adopted by the jurisdiction. Indicating Device: An instrument that measures and registers certain operating conditions used for monitoring and control, such as temperatures and pressures, which can be read on a gauge, control display screen, or both. Indirect System: A system in which a secondary coolant that is cooled or heated by the refrigeration system is circulated to the air or other substance to be cooled or heated. Indirect-Closed System: A system in which a secondary coolant passes through a closed circuit in the air or other substance to be cooled or heated. Indirect Open-Spray System: A system in which a secondary coolant is in direct contact with the air or other substance to be cooled or heated. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 2

16 Industrial Occupancy: A premises or a portion thereof that is not open to the public, where access is controlled such that only authorized personnel are admitted and that is used to manufacture, process, or store goods. Large Mercantile Occupancy: A premises or portion thereof where more than 100 persons congregate to purchase merchandise. Machinery: Refrigeration equipment forming a portion of a refrigeration system, including but not limited to compressors, condensers, pressure vessels, evaporators and refrigerant pumps. Machinery Room: An enclosed space that, where required by this standard to contain equipment, must comply with the requirements set forth in Chapter 6. Mechanical Code: The mechanical code adopted by the jurisdiction. Monitored: A means of continuous oversight, such as notification of on-site staff, a third party alarm service or a responsible party. Noncombustible Material: A material that, when tested in accordance with ASTM E136, has at least three of four specimens tested meeting all of the following criteria: 1. The recorded temperature of the surface and interior thermocouples shall not at any time during the test rise more than 54 F (30 C) above the furnace temperature at the beginning of the test. 2. There shall not be flaming from the specimen after the first 30 seconds. 3. If the weight loss of the specimen during testing exceeds 50 percent, the recorded temperature of the surface and interior thermocouples shall not at any time during the test rise above the furnace air temperature at the beginning of the test, and there shall not be flaming of the specimen. Occupied Space: A portion of a premises that is routinely accessible to or occupied by people on a parttime or full-time basis. *Packaged System: A fabricated and assembled self-contained closed-circuit refrigeration system, or a large portion thereof, either enclosed within its case or framework or unenclosed. PPM: Parts per million concentration in air. Principal Machinery Room Door: An exterior door that has been designated as a primary emergency egress door for a machinery room. *Public Assembly Occupancy: A premises portion thereof where large numbers of people congregate and from which occupants cannot quickly vacate. Restricted: Open to access by only authorized personnel and specifically excluding public access. Self-Contained: Having all essential equipment, piping and devices to form a complete closed-circuit mechanical refrigeration system, except energy and control connections, and contained in a case or framework. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 3

17 Surge Drum: A receiver installed on the low-pressure side of a refrigeration system that is closecoupled to one or more evaporators and provides liquid feed and a liquid-from-vapor disengagement space to ensure that dry vapor is returned to the compressor. Tight Construction: Solid construction with holes or openings that are either sealed or provided with tight-fitting doors to control the transfer of liquid, moisture, air and vapor. Tight-Fitting Door: A tightly constructed door with seals to minimize gap clearances between the entire door perimeter and its fixed door frame, which is intended to control the transfer of liquid, moisture, air and vapor. Trained Operator: An individual having training and experience, which qualify that individual to operate and perform basic system inspections on a closed-circuit refrigeration system with which he or she has become familiar. Unoccupied Area: A portion of premises accessible to only authorized personnel performing scheduled walk-throughs for operational checks or maintenance service on equipment. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 4

18 Chapter 3. Reference Standards 3.1 American Society of Mechanical Engineers (ASME), standards as follows: ASME B&PVC, Boiler and Pressure Vessel Code, Pressure Vessels, Section VIII, Division 1 (2013). ASME B31.5 (2013), Refrigeration Piping and Heat Transfer Components. 3.2 American Society of Testing and Materials (ASTM), standards as follows: ASTM A53/A53M (2012), Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc- Coated, Welded and Seamless. ASTM A197/A197M-00 (2011), Standard Specification for Cupola Malleable Iron. ASTM E136 (2012), Standard Test Method for Behavior of Materials in a Vertical Tube Furnace at (750 C). 3.3 Compressed Gas Association (CGA), Standard G-2 (1995), Eighth Edition. 3.4 International Institute of Ammonia Refrigeration (IIAR), standards as follows: ANSI/IIAR 1 (2012), Definitions and Terminology Used in IIAR Standards. ANSI/IIAR 3 (2012), Ammonia Refrigeration Valves. ANSI/IIAR 5 (2013), Start-up and Commissioning of Closed-Circuit Ammonia Refrigeration Systems. ANSI/IIAR 7 (2013), Developing Standard Operating Procedures for Closed-Circuit Ammonia Mechanical Refrigerating Systems. 3.5 International Safety Equipment Association (ISEA), ANSI/ISEA Z358.1, World Safety Standard for Emergency Eyewash and Shower Equipment (2009). 3.6 National Fire Protection Association (NFPA), NFPA Standard 70, National Electrical Code (NEC) (2011). 3.7 Occupational Safety and Health Administration (OSHA), U.S. Department of Labor, regulations as follows: 29 CFR (2012), General Requirements for All Machines. 29 CFR (2012) Mechanical Power Transmission Apparatus. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 5

19 Part 2 Chapter 4. Design and Installation Considerations Affecting Construction Location of Ammonia Refrigeration Machinery 4.1 General. The location of ammonia refrigeration machinery shall comply with this chapter. Ammonia refrigeration machinery located in a machinery room complying with Chapter 6 or located outdoors in accordance with Section shall be permitted in conjunction with a secondary coolant that serves any occupancy in accordance with Section *Permissible Equipment Locations. Ammonia refrigeration machinery shall be located in a machinery room complying with Chapter 6 unless otherwise permitted by this section Listed Equipment. Listed equipment containing not more than 6.6 lbs (3 kg) of ammonia and installed in accordance with the listing and the manufacturer s instructions shall be permitted in any occupancy without a machinery room Outdoor Installations. Ammonia refrigeration machinery shall be permitted to be installed outdoors. Ammonia refrigeration machinery, other than piping, installed outdoors shall be located not less than 20 feet from building openings, except for openings to a machinery room or openings to an industrial occupancy complying with Section *Industrial Occupancies. The following ammonia refrigeration machinery shall be permitted to be installed outside of a machinery room in industrial occupancies complying with Chapter Evaporators used for refrigeration or dehumidification. 2. Condensers used for heating the space in which they are located. 3. Valves, including but not limited to control and pressure-relief valves, and connecting piping, any of which are associated with Items 1 and An ammonia refrigeration system or portions thereof with a total connected compressor power not exceeding 100 HP (74.6 kw) *Public Assembly, Commercial and Large Mercantile Occupancies. Where approved, ammonia refrigeration machinery shall be permitted outside of a machinery room for applications other than human comfort in a public assembly occupancy, commercial occupancy or large mercantile occupancy. The quantity of ammonia shall be limited such that a complete discharge from any independent refrigerant circuit will not result in an ammonia concentration exceeding 320 ppm in any room or area where equipment containing ammonia is located. The calculation procedure for determining the concentration level shall comply with Section 5.4. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 6

20 Chapter 5. General System Design Requirements 5.1 General. The design of closed-circuit ammonia refrigeration systems shall comply with this chapter. 5.2 Anhydrous Ammonia Specifications *Refrigerant-Grade Ammonia. Refrigerant-grade anhydrous ammonia that meets or exceeds the minimum requirements of CGA Standard G-2 shall be used for the initial charge and subsequent top-off to fill the system to the operating intended inventory Purity Requirements. Ammonia refrigerant shall comply with Table 5.2. Table 5.2 Purity Requirements Ammonia Content Non-Basic Gas in Vapor Phase Non-Basic Gas in Liquid Phase Water Oil (as soluble in petroleum ether) Salt (calculated as NaCl) Pyridine, Hydrogen Sulfide, Naphthalene 99.95% minimum 25 ppm maximum 10 ppm maximum 33 ppm maximum 2 ppm maximum None None 5.3 Machinery location. The location of ammonia refrigeration machinery shall comply with Chapter *Volume Calculation for Determining Concentration of an Ammonia Release. For the purpose of applying Section and Section , the volume used to calculate the potential ammonia concentration in the event of a release shall comply with this section. The volume used to calculate the potential ammonia concentration shall be the gross volume of a room or space into which released ammonia will disperse based on the smallest gross volume in which the release could accumulate *Wall Openings Permanent wall openings between rooms or spaces containing a refrigeration system, or equipment, shall not be considered when determining the volume. EXCEPTION: Where the designer determines, based on the size and elevation of permanent wall openings or a mechanical ventilation system, that migration and dilution of a release over the combined spaces will occur, the volume shall be the combined space, provided that the openings or mechanical ventilation are clearly identified as the basis for the design analysis Spaces Above Suspended Ceilings. The space above a suspended ceiling shall not be used in determining the volume of the area in which the ceiling is located unless the space above the ceiling is used as part of the air distribution system. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 7

21 5.4.3 *Interconnected Floor Levels and Mezzanines. Where a refrigeration system, or portion thereof, is located in a room or space containing multiple floor levels connected through an open atrium or where there is a mezzanine open to a room or space, the combined volume of interconnected floors and mezzanines shall be used *Mechanical Ventilation Considerations. Where a refrigeration system, or portion thereof, is located: 1) In an area served by a mechanical ventilation system, 2) Within an air handler or 3) In an air distribution duct system, the volume of the rooms or spaces connected by the ventilation or duct system, including the volume of the connected supply and return air ducts and any connecting plenum, shall be used. EXCEPTION: The smaller of the volumes on either side of a damper shall be used where portions of the ventilation or duct system are subject to being isolated by dampers, other than: 1) Fire dampers, 2) Smoke dampers, 3) Combination fire and smoke dampers, or 4) Dampers that continuously maintain not less than 10-percent airflow. 5.5 Use of Ammonia Refrigeration with Secondary Coolants. Ammonia refrigeration machinery located in a machinery room complying with Chapter 6 or outdoors in accordance with Section shall be permitted to be used in conjunction with a secondary coolant that serves any occupancy, provided that the system is one of the following types and that use of the secondary coolant is in accordance with the Mechanical Code: 1. Indirect closed system. 2. Indirect open-spray system with the pressure of the secondary coolant always exceeding the pressure of the ammonia system, regardless of whether the system is in operation or standby and considering all temperature conditions to which equipment could be exposed. 3. Double-indirect open-spray system. 5.6 *System Design Pressure. Design pressure shall be in accordance with this section General *Allowance for Pressure-limiting and Pressure-relief Devices. In determining the design pressure, an allowance shall be provided for setting pressure-limiting devices and pressure-relief devices to avoid equipment shutdown or loss of ammonia during normal operation. Systems Not Exceeding 22 pounds of Ammonia. For systems containing not more than 22 pounds of ammonia, portions of the system that are protected by a pressurerelief device shall not be required to have a design pressure that exceeds the set pressure of the pressure relief protection. Equipment and Piping Connected to a Pressure Vessel. Equipment and piping connected to pressure vessels and subject to the same pressure as the pressure vessel shall have a design pressure that is equal to or greater than the set pressure of the pressure relief protection for the pressure vessel. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 8

22 Compressors Used as Boosters. Compressors used as boosters and discharging into the suction side of another compressor shall be considered as part of the low-pressure side for the purpose of determining the design pressure. Connecting to Existing Low-pressure Equipment. Where new low-pressure side equipment is connected to an existing system that was in operation prior to the adoption of this Standard, the design pressure of the new low-pressure-side portion of the system shall be permitted to equal the design pressure of the existing low-pressure side, provided that the new low-pressure side operates under the same conditions as the existing system Pressure Developed During Operation, Standby or Shipping Conditions. The design pressure shall be equal to or greater than the maximum pressure that could occur during operating, standby or shipping conditions. Normal Operating Conditions. The design pressure shall be equal to or greater than the maximum pressures that could occur during normal operating conditions, including conditions created by expected fouling of heat exchange surfaces. *Standby Conditions. The design pressure shall be equal to or greater than the maximum pressure that could occur during standby conditions, which shall include conditions that can normally occur when the system is not in operation. For lowpressure side equipment, the design pressure shall be equal to or greater than the pressure developed in the low-pressure side of the system from equalization or heating due to changes in ambient temperature after a system has stopped. Shipping. The design pressure for both low-pressure side and high-pressure side equipment that is shipped as part of a gas- or ammonia-charged system shall equal or exceed the maximum internal pressures associated the highest anticipated temperature exposure during shipment Saturation Pressure and Minimum Permissible Design Pressure. The design pressure shall not be less than the saturation gauge pressure corresponding to the following temperatures and shall not be less than the specified minimum. 1. Low pressure side: 10 F (5.6 C) greater than the 1% ambient dry bulb temperature for the installation location or F (45.9 C), whichever is greater. The minimum design pressure shall be 250 psig (1724 kpa). 2. High-pressure side of water-cooled or evaporatively-cooled systems: 30 F (16.7 C) higher than the highest summer 1% wet-bulb temperature for the location, 15 F (8.3 C) higher than the highest design leaving condensing-water temperature for which the equipment is designed, or F (45.9 C), whichever is greater. The minimum design pressure shall be 250 psig (1724 kpa). 3. High-pressure side of air-cooled systems: 30 F (16.7 C) higher than the highest summer 1% design dry-bulb temperature for the location, but not less than 122 F (50 C). The minimum design pressure shall be 250 psig (1724 kpa) Vacuum. Refrigeration equipment shall be designed for a vacuum of 29.0 inches (737 mm) of mercury. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 9

23 5.7 System Design Temperature. Equipment shall be designed to operate within the full range of temperatures associated with the system design and for the full range of ambient temperatures to which equipment will be exposed at the installation location. 5.8 Materials General Metallic Materials Materials used in the construction of an ammonia refrigeration system shall be suitable for ammonia refrigerant at the coincident temperature and pressure to which the system will be subjected. *Materials that deteriorate in the presence of ammonia, refrigerant lubricating oil, a combination of both, or any expected contaminant shall not be used. Cast iron, malleable iron, nodular iron, steel, cast steel, and alloy steel shall be permitted in accordance with ASME B31.5 or ASME B&PVC, Section VIII, Division 1, or international equivalent as applicable. Other metallic materials, including but not limited to aluminum, aluminum alloys, lead, tin, and lead-tin alloys shall be permitted in accordance with Section Where tin and tin-lead alloys are used, the alloy composition shall be verified as suitable for temperature exposures, as specified in Section 5.7. Zinc, copper, and copper alloys shall not be used to contain or be in contact with ammonia. Copper-containing anti-seize and lubricating compounds shall not be used. Copper, as a component of brass alloys, shall be permitted in rotating shaft bearings and other non-refrigerant containment uses Non-Metallic Materials Non-metallic materials shall be permitted in accordance with Section Non-metallic materials shall be permitted in accordance with ASME B31.5 or ASME B&PVC, Section VIII, Division 1, or international equivalent as applicable. 5.9 *Purging. Means shall be provided to remove air and other non-condensable gases from the refrigeration system. Atmospheric discharge from vents shall comply with Section Oil Management General. Provisions shall be made in the design for removing oil from locations in piping and equipment where oil accumulation is expected Compressors. Compressor packages shall have a means to sample oil for periodic oil analysis in accordance with the manufacturer s recommendations. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 10

24 Oil Removal. Oil removal shall be accomplished by one or more of the following: 1. A rigid-piped oil return system. 2. A vessel equipped with an oil drain valve in series with a self-closing emergency stop valve. 3. Piping which provides the capability to isolate and remove ammonia to another portion of the system. 4. A valve and piping assembly at the draining point where oil is removed from the system. At a minimum, an oil drain valve in series with a self-closing emergency stop valve is required Temporary Piping. Where draining of oil requires the use of temporarily-attached rigid piping, such piping shall be supported and shall have tight connections Insulation *General. Equipment surfaces, not intended for heat exchange, shall be insulated to prevent or control condensation. See Section 5.12 for condensation control for piping and fittings. EXCEPTIONS: 1. Valve groups and other equipment shall be permitted to be uninsulated where necessary for service access provided that the vapor retarder is sealed to the piping or equipment where insulation of adjoining piping terminates. 2. Piping and fittings constructed of corrosion-resistant materials or protected with a corrosion-resistant treatment shall be permitted to be uninsulated if they are routinely defrosted or are otherwise managed to limit ice accumulation. Where defrost will be the method of ice control, a means to control and drain condensate shall be provided Hot Discharge Lines. Hot discharge lines having an external surface temperature of 140 degrees F (60 degrees C) or higher and are located less than 7.25 feet (2.2 m) above the floor or are located adjacent to passageways, aisles, walkover stairs or landings shall be provided with: 1) Warning signs, 2) Insulation, or 3) Guards to prevent contact Condensation Control for Piping and Fittings. Piping and fittings that convey brine, refrigerant, or coolants shall be insulated in accordance with Section 5.11, treated, or otherwise protected to mitigate condensation where, during normal operation, the surface temperature could fall below the dew point of the surrounding air in an area where condensation could develop and become a hazard to occupants or cause damage to the structure, electrical equipment or other equipment Foundations, Piping, Tubing, and Equipment Supports General. Supports and anchorage for refrigeration equipment shall be designed in accordance with the Building Code Combustibility. Structural supports shall be noncombustible. Base supports located on the roof beneath piping or equipment stands shall be permitted to be constructed with pressuretreated lumber Seismic Joints and Restraints. Seismic joints and restraints shall be provided as required by the Building Code. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 11

25 Manufacturers Recommendations and Expected Loads. Supports and foundations shall meet or exceed the manufacturers recommendations and shall be designed to carry expected loads Vibration and Movement Resistance. Supports and foundations shall be designed to prevent excessive vibration or movement of piping, tubing and equipment Service Provisions *General. Equipment shall be accessible for maintenance, as required by the Mechanical Code Charging Connection Security. Refrigeration system charging connections located outdoors shall be locked or otherwise restricted to access by only authorized personnel *Maintenance and Functional Testing. Design provisions for maintenance and functional testing of safety controls shall be provided. Such provisions shall be permitted to include but are not limited to shut-off valves and capped or plugged connection points that comply with this Standard. Provisions for functional testing shall not require disassembly of ammoniacontaining portions of the system Pressure Gauges. Where a pressure gauge is installed on the high-side of the refrigeration system, the gauge shall be capable of measuring and displaying not less than 120-pecent of the system design pressure *Serviceability. Serviceable equipment shall be designed so that it can be serviced *Service Isolation Valves. Serviceable equipment shall have manual isolation valves Testing EXCEPTION: Packaged systems and portions of built-up systems shall be permitted to have pump-down arrangements that provide for the removal or isolation of ammonia for servicing one or more devices in lieu of isolation valves Strength Testing. Equipment containing ammonia shall be strength tested to the minimum pressure exceeding the design pressure specified in Chapter 8 through Chapter 16, subsequently leak tested, and proven tight at a pressure not less than the design pressure. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 12

26 Ultimate Strength. Pressure-containing equipment shall comply with Sections and EXCEPTION: The following shall be permitted to comply with Section in lieu of complying with this section: 1. Pressure vessels. 2. Provided that they are not part of a pressure vessel: piping including valves; evaporators; condensers; and heating coils with ammonia as the working fluid. 3. Pressure gauges. 4. Refrigerant pumps. 5. Control mechanisms. Pressure-containing equipment shall be in accordance with one of the following: 1. Listed individually. 2. Listed as part of the complete refrigeration system. 3. Listed as a subassembly. 4. Designed, constructed and assembled to have an ultimate strength sufficient to withstand three times the design pressure for which it is rated. 5. Designed in accordance with Section VIII, Division 1, ASME B&PVC or international equivalent, as applicable. *Secondary coolant sides of equipment exempted from ASME B&PVC, Section VIII, Division 1, or international equivalent shall be designed, constructed and assembled to have ultimate strength sufficient to withstand the greater of 150 psig [1724 kpa gauge] or two times the design pressure for which they are rated. Equipment designed based on the exception to Section shall be required to comply with additional requirements in Chapter 8 through Chapter 16 and ASME B31.5, as applicable Signage, Labels, Pipe Marking and Wind Indicators Machinery Room Signage. Machinery room signage shall comply with Section Machinery Labels. Refrigeration machinery shall be provided with permanent labels. For refrigeration machinery having an internal volume of more than three cubic feet (0.085 cubic meters) containing ammonia, the permanent label shall include the state of the contained ammonia, being liquid, vapor, or both; the type of machinery; and a title that matches the system drawings Emergency Shutdown Valve Identification and Tagging. Valves required for emergency shutdown of the system shall be clearly identified on a diagram that is available to personnel onsite. The procedures and diagram shall be reviewed and updated, as necessary, when changes are made that affect emergency shutdown procedures. Valves used for emergency shutdown of the system shall also be uniquely identified on the actual system. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 13

27 Nameplates Equipment shall have a nameplate with minimum data that describes or defines the manufacturer s information and design limits and purpose as specified in Chapter 8 through Chapter 16. *The original nameplate for pressure vessels shall be affixed as specified in ASME B&PVC, Section VIII, Division 1, Section UG-119(e) or international equivalent. *Duplicate nameplates shall comply with the following: 1. Where duplicate nameplates are required for pressure vessels and heat exchangers constructed in accordance with ASME B&PVC, Section VIII, Division 1or international equivalent, the duplicate nameplate shall comply with ASME B&PVC, Section VIII, Division 1, Section UG-119(e) or international equivalent. 2. A duplicate nameplate, if used, shall be installed on the skirt, support, jacket, or other permanent attachment to a vessel. 3. Duplicate nameplates shall be permanently marked DUPLICATE. 4. Duplicate nameplates shall be obtained only from the original equipment manufacturer or the manufacturer s assignee. 5. The installer shall certify to the manufacturer that the duplicate nameplate has been applied to the proper vessel, in accordance with the governing edition of ASME B&PVC, Section VIII, Division 1 Section UG-119(d) or international equivalent. The installer shall provide a copy of the certification to the owner, who shall retain the copy with the U1A form, or equivalent, for the vessel *Pipe Marking. Ammonia piping mains, headers and branches shall be identified with the following information. The marking system shall either be one established by a recognized model code or standard or one described and documented by the facility owner. 1. AMMONIA 2. Physical state of the ammonia, being liquid, vapor, or both. 3. Relative pressure level of ammonia, being low or high as applicable. 4. Name of the pipe, which shall be permitted to be abbreviated. 5. Direction of flow *Wind Indicator. Where a sock, pennant or other wind indicator is provided, it shall in accordance with specifications and locations prescribed by emergency planning documents. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 14

28 5.17 Emergency Shutdown Documentation. It shall be the duty of the person in charge of the premises on which the refrigeration system is installed to provide a schematic drawing or sign giving directions for the emergency shutdown of the system at a location that is readily accessible to trained refrigeration system staff and trained emergency responders who are familiar with the system. Schematic drawings or signage shall include the following: 1. Instructions with details and steps for shutting down the system in an emergency. 2. The name and contact telephone numbers of the refrigeration operating, maintenance and management staff, emergency responders, and safety personnel. 3. The names and telephone numbers of all corporate, local, state, and federal agencies to be contacted as required in the event of a reportable incident. 4. Type of ammonia in the systems. 5. Type and quantity of lubricants in the systems. 6. Field test pressures applied Equipment Enclosures General. Enclosures shall be suitable for the installation location and shall be provided with protection from physical and environmental damage, as required for the installed location. Where the installation location requires a specified level of cleanliness, the enclosure shall be designed to meet applicable requirements Egress. Operational and maintenance service egress shall be provided by access panels or doors or the design shall provide for remote service by removal of the enclosure or the contents from the installed location General Safety Requirements Protection from Physical Damage. Where installed in a location subject to physical damage, guarding or barricading shall be provided *Rotating Parts. Exposed rotating parts shall be protected with screens or guards in accordance with OSHA 29 CFR and 29 CFR Ammonia Storage. Ammonia shall be stored in cylinders or vessels designed for ammonia containment *Used Equipment. Used equipment to be installed in connection with an existing system shall comply with the requirements of the standard that regulated the installation of the existing system, including the minimum design pressure. Used equipment to be installed in connection with a new system shall meet the requirements of this Standard *Static and Dynamic Loads. Equipment shall be designed to structurally withstand the expected static and dynamic loads *Illumination of Construction Areas. During construction, illumination shall be available for outdoor refrigeration equipment work areas *Means of Egress. Means of egress shall comply with the Building Code Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 15

29 Chapter 6. Machinery Rooms 6.1 General. Where a machinery room is required by Chapter 4 to contain machinery, the machinery room shall comply with this chapter. 6.2 Construction. Machinery rooms shall be constructed in accordance with the Building Code and the requirements of this section *Separation and Fire Protection. The machinery room shall be separated from the remainder of the building by tight-fitting construction having a one-hour fire-resistance rating. Doors shall comply with Section EXCEPTION: The one-hour fire-resistance rating shall not be required where the machinery room is equipped with an automatic fire sprinkler system. Tight fitting construction must still be provided Piping Supports. Where piping is supported by the floor, roof or ceiling structure, the structure or foundation supporting the piping shall be designed to support the expected static and dynamic loads, including seismic loads. Foundations and supports shall be in accordance with the Building Code Equipment Supports. Foundations, floor slabs, and supports for compressor units and other equipment located within the machinery room shall be of noncombustible construction and capable of supporting the expected static and dynamic loads imposed by such units, including seismic loads. Foundations and supports shall be in accordance with the Building Code. A compressor or condenser supported from the ground shall rest on a concrete pad or base or shall be furnished with a support base for setting directly on and anchoring to the foundation Vibration Control. Machinery shall be mounted in a manner that prevents excessive vibration from being transmitted to the building structure or connected equipment. Isolation materials shall be permitted between the foundation and equipment Airflow from Occupied Spaces. Air shall not flow to or from an occupied space through a machinery room unless the air is ducted and sealed to prevent ammonia leakage from entering the airstream. Access doors and panels in ductwork and air-handling units located in a machinery room shall be gasketed and tight-fitting. 6.3 Access and Egress General. Equipment installed in machinery rooms shall be located in such a manner as to allow egress from any part of the room in the event of an emergency, as required by Section , and to provide clearances required for maintenance, operation and inspection according to manufacturers instructions Maintenance Access. Maintenance access shall comply with Section Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 16

30 6.3.3 Access to Valves. *Manually-operated valves that are inaccessible from floor level shall be operable from portable platforms, fixed platforms, ladders, or shall be chain-operated. Manually operated isolation valves identified as being part of the system emergency shutdown procedure shall be directly operable from the floor or chain-operated from a permanent work surface. Emergency valve identification shall comply with Section Restricted Access. Access to a machinery room shall be restricted to authorized personnel. Signage on machinery room doors shall comply with Section Combustible Materials. Combustible materials shall not be stored in machinery rooms. EXCEPTION: This provision shall not apply to spare parts, tools and incidental materials necessary for the operation and maintenance of the refrigeration system. 6.5 Open Flames and Hot Surfaces. Fuel-burning appliances and equipment and surfaces having temperatures exceeding 800 F (427 C) shall not be installed in a machinery room. 6.6 Piping EXCEPTIONS: 1. Fuel-burning appliances and equipment shall be permitted in a machinery room where combustion air to the fuel-burning appliance is ducted from outside of the machinery room and sealed to prevent ammonia leakage from reaching the combustion chamber. 2. Fuel-burning appliances and equipment shall be permitted in a machinery room where an ammonia detector automatically shuts off the combustion process upon detection of ammonia. 3. The use of matches, lighters, sulfur sticks, welding equipment and similar portable devices shall be permitted except when charging is being performed and when oil or ammonia is being removed from the system. 4. Internal combustion engines powering compressors shall be permitted in a machinery room Insulation. Piping and fittings shall be insulated as required by Section 5.11 and Section Pipe Penetrations. Pipes penetrating the machinery room separation shall be sealed to the walls, ceiling, or floor through which they pass in accordance with Section Where Section requires that the separation have a fire rating, pipe penetrations shall be fire stopped in accordance with the Building Code Pipe Marking. Piping shall be marked as required by Section Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 17

31 6.6.4 Connection of Ammonia Cylinders. Ammonia cylinders shall not be connected a refrigeration system unless ammonia is in the process of being transferred by authorized personnel. 6.7 Eyewash/Safety Shower General. Each machinery room shall have access to a minimum of two eyewash/safety shower units, one of which shall be located inside the machinery room and one of which shall be located outside of the machinery room. Additional eyewash/safety shower units shall be installed such that an identified hazard in the machinery room is no more than 55 feet from an eyewash/safety shower unit. EXCEPTION: A single permanent eyewash/safety shower unit, located either inside or outside of a machinery room shall be permitted provided that an operational procedure has been developed to make an additional eyewash/safety shower unit available whenever maintenance procedures with an ammonia exposure risk are performed. The additional eyewash/safety shower unit shall be located not more than 55 feet from the identified hazard associated with the maintenance work. The additional eyewash/safety shower unit shall be permitted to be portable or temporary and located either: 1) Outside of the machinery room, where the permanent installation is located inside, or 2) Inside of the machinery room where the permanent installation is located outside of the room Path of Travel. The path of travel from an identified hazard to at least one eyewash/safety shower unit shall be unobstructed and shall not include intervening doors. EXCEPTION: Where a single eyewash/safety shower unit is provided outside the machinery room in accordance with the exception to Section 6.7.1, a single machinery room exit door shall be permitted in the path of travel Installation Standard. Emergency eyewash/safety shower unit installations shall comply with ANSI/ISEA Z Electrical Safety General. Electrical equipment and wiring shall be installed in accordance with the Electrical Code Hazardous (Classified) Locations. Machinery rooms shall be designated as Ordinary Locations, as described in the Electrical Code, where the machinery room is provided with emergency ventilation in accordance with Section Machinery rooms not provided with emergency ventilation shall be designated as not less than a Class I, Division 2, Group D Hazardous (Classified) Locations, and electrical equipment installed in the machinery room shall be designed to meet this requirement. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 18

32 6.8.3 Design Documents. Electrical design documents shall indicate whether the machinery room is designated as an Ordinary Location or as a Hazardous (Classified) Location. Where the machinery room is designated as a Hazardous (Classified) Location, the Class, Division and Group of the electrical classification, as required by the Electrical Code, shall be indicated in the documentation. 6.9 Drains General. Floor drains shall be provided to dispose of wastewater Contaminant Control. Where a drainage system is not designed for handling oil, secondary coolants or other liquids that might be spilled, a means shall be provided to prevent such substances from entering the drainage system Control of Ammonia Spills. A means shall be provided to limit the spread of a liquid ammonia spill such that liquid ammonia that has entered a machinery room drainage system does not expose occupied areas outside of the machinery room Entrances and Exits General. Machinery rooms exceeding 1,000 square feet (93 m 2 ) in area shall have not less than two exit- or exit-access doors. Where two doors are required, one door shall be permitted to be served by a fixed ladder or an alternating tread device. Doors shall be separated by a horizontal distance equal to or greater than one-half of the maximum horizontal dimension of room. All portions of a machinery room shall be within 150 feet (45,720 mm) of an exit- or exit-access door, unless an increased travel distance is permitted by the Building Code Door Features. Machinery room doors shall be self-closing and tight-fitting. Doors that are part of the means of egress shall be equipped with panic hardware and shall be side-hinged to swing in the direction of egress for occupants leaving the machinery room. Where the machinery room is not provided with fire sprinklers, doors communicating with the building interior shall be 1-hour fire-rated. Doors to the outdoors shall be fire-rated where required by the Building Code based on the fire-rating required for exterior wall openings *Required Exterior Door. Machinery rooms shall have a minimum of one exit door that opens directly to the outdoors or to a vestibule that leads directly to the outdoors. EXCEPTION: Machinery rooms equipped with a fire sprinkler system and having a floor area of 500 square feet (46.5 m²) or less shall not be required to have a door that opens directly to the outdoors or to a vestibule leading directly to the outdoors Separation from Fire Escapes and Stairways. Exit doors leading to the outdoors shall not be located beneath a fire escape or open stairway. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 19

33 6.11 Lighting General. Machinery rooms shall be equipped with light fixtures delivering a minimum of 30 foot-candles [320 lumens/m2] at the working level, 36 inches (0.91 m) above a floor or platform Light Control. A manual control for the illumination source shall be provided. Occupancy sensors shall be permitted as an additional control for lighting, but not in lieu of a manual control Emergency Control Switches Emergency Stop Switch. A clearly-identified emergency shutoff switch with a tamperresistant cover shall be located outside and adjacent to the designated principal machinery room door leading to the outdoors. The switch shall provide off-only control of refrigerant compressors, refrigerant pumps, and normally-closed automatic refrigerant valves located in the machinery room. The function of the switch shall be clearly marked by signage near the controls Emergency Ventilation Control Switch. A clearly-identified control switch for emergency ventilation with a tamper-resistant cover shall be located outside and adjacent to the designated principal machinery room door leading to the outdoors. The switch shall provide ON/AUTO override capability for emergency ventilation. The function of the switch shall be clearly marked by signage near the controls Ammonia Detection and Alarm General. Machinery rooms shall be provided with Level 3 detection and alarm in accordance with Section The detection and alarm system shall comply with Chapter Alarm Response Detection of ammonia concentrations less than 25 ppm requires no alarm or response. *Detection of ammonia concentrations equal to or exceeding 25 ppm shall activate visual indicators, activate an audible alarm, and stop fans and close dampers to prevent inadvertent spread of ammonia vapor as specified in Section The visual indicator and audible alarm shall be permitted to automatically reset if the ammonia concentration drops below 25 ppm. *Detection of ammonia concentrations equal to or exceeding 160 ppm shall activate visual indicators and an audible alarm and shall activate emergency ventilation, where required, in accordance with Section Once activated, emergency ventilation continue to operate until being manually reset by a switch located in the machinery room. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 20

34 Detection of ammonia concentrations that exceed a detector s upper detection limit or 40,000 ppm (25% LFL), whichever is lower, shall activate visual indicators and an audible alarm and shall activate emergency ventilation, where required, in accordance with Section Once activated, emergency ventilation continue to operate until being manually reset by a switch located in the machinery room. In addition, the following equipment in the machinery room shall be automatically de-energized: 1. Refrigerant compressors. 2. Refrigerant pumps. 3. Normally-closed automatic refrigerant valves Ventilation *Occupant Breathing Air. During occupied conditions, outdoor air shall be provided at a rate of not less than 0.5 cfm per square foot ( m3/s m2) of machinery room area or 20 cfm (0.009 m3/s) per occupant, whichever is greater General Exhaust and Air Conditioning Equipment. Machinery room exhaust fans and air conditioning equipment that is not intended for exhausting ammonia vapor shall be deenergized and fan dampers, where provided, shall close upon detection of ammonia in accordance with Section Exhaust Ventilation. Machinery rooms shall be vented to the outdoors by means of a mechanical exhaust ventilation system. Mechanical exhaust ventilation system shall be automatically activated by ammonia leak detection or temperature sensors, and the system shall also be manually operable. Mechanical exhaust ventilation systems shall be designed to produce not less than the temperature control ventilation rate required by Section and the emergency exhaust ventilation rate required by Section Fan Options. Multiple fans or multispeed fans shall be permitted to provide both temperature control exhaust ventilation in accordance with Section and emergency exhaust ventilation in accordance with Section Fans used for both temperature control and emergency ventilation shall be controlled in a manner that provides the emergency ventilation rate when emergency ventilation is activated. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 21

35 Inlet Air Exhaust Outdoor make-up air shall be provided to replace air being exhausted and shall be designed to maintain negative pressure in the machinery room, not to exceed 0.25 in. (6.4 mm) water column. Make-up air supply locations in the machinery room shall be positioned to prevent short-circuiting of the make-up air directly to the exhaust. Make-up air openings shall be covered with a corrosion-resistant screen of not less than ¼ mesh or equivalent protection. Intakes for make-up air shall be positioned to draw uncontaminated outdoor air and avoid recirculation of exhausted air. Intakes for make-up air to the machinery room shall only serve the machinery room. Motorized louvers or dampers, where utilized, shall fail to the open position upon loss of power. Where direct openings or openings with ducts are not provided to supply make-up air, make-up air shall be provided by fans or fans with ducts. *Machinery room exhaust shall be to the outdoors not less than 20 feet (6 m) from a property line or openings into buildings, measured horizontally, vertically, or a combination of both. Machinery room exhaust shall discharge vertically upward with a minimum discharge velocity of 2,500 feet-per-minute (762 M/min.) at the required emergency ventilation flow rate. Exhaust air ducts from the machinery room shall only serve the machinery room. Machinery room exhaust fans, regardless of function, shall be equipped with nonsparking blades. *Emergency exhaust fan motors located in the air stream or inside the machinery room shall be of the totally-enclosed type. Fan motors meeting this requirement are not required to be listed for use in hazardous (classified) locations. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 22

36 Temperature Control Ventilation *Temperature control mechanical ventilation design capacity shall be the volume required to limit the room dry bulb temperature to 104 F (40 C), taking into account the ambient heating effect of machinery in the room and with the make-up air entering the room at a 1% design dry bulb temperature. The emergency ventilation system shall be permitted to be used to supplement temperature control ventilation, and vice-versa. EXCEPTION: A reduced temperature control ventilation rate shall be permitted where a means of cooling is provided or room electrical equipment is designed to accommodate temperatures exceeding a dry bulb temperature of 104 F (40 C), in accordance with UL Listings and the Electrical Code. Partial operation of a multiple-fan system or multi-speed fans shall be permitted to deliver the temperature control ventilation design capacity. Temperature control mechanical ventilation shall be continuous or shall be activated by both of the following: 1. A thermostat measuring space temperature. 2. A manual control provided in accordance with Section , where temperature control ventilation is designed to contribute to emergency ventilation Emergency Ventilation *Emergency mechanical ventilation systems shall provide not less than 30 air changes per hour based on the gross machinery room volume. The emergency ventilation system shall be permitted to include temperature control ventilation fans that meet the requirements of Section and Section , Item 2. EXCEPTION: Where approved, emergency mechanical ventilation shall not be required for a limited-charge refrigeration system that will not yield an ammonia concentration exceeding 40,000 ppm in the machinery room following a release of the entire charge from the largest independent refrigerant circuit, based on the volume calculation determined in accordance with Section 5.4. The designer shall provide a copy of the calculations to be retained at the site. Emergency mechanical ventilation shall be activated by both of the following: 1. Ammonia leak detection complying with Section A manual control provided in accordance with Section Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 23

37 Emergency ventilation shall be powered independently of the equipment within the machinery room and shall continue to operate regardless of whether emergency shutdown controls for the machinery room have been activated. A monitored location shall be notified upon loss of power to or failure of the emergency mechanical ventilation system Ventilation Remote Controls. Emergency control switches for ventilation shall comply with Section Testing *A schedule for testing the mechanical ventilation system shall be established based on manufacturers recommendations, unless modified based on documented experience. Testing shall include operation of the ventilation system based on ammonia detection at the concentration set forth in Section and by manual controls required by Section Where manufacturers recommendations are not provided, the mechanical ventilation system shall be tested not less than twice per year. Alarm testing shall comply with Section Signage. Signage shall be provided in accordance with this section *NFPA 704 Placards. Buildings and facilities with refrigeration systems shall be provided with placards accordance with NFPA 704 and the Mechanical Code Alarm Signage. Alarm signage shall be provided in accordance with Section Restricted Access Signage. Each machinery room entrance doors shall be marked with a permanent sign in accordance with Section to indicate that only authorized personnel are permitted to enter the room. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 24

38 Chapter 7. Refrigeration Equipment Located in Areas Other Than Machinery Rooms 7.1 General. Industrial, public assembly, commercial and large mercantile occupancies that are permitted by Section 4.2 to contain ammonia refrigeration systems or equipment outside of a machinery room shall comply with this chapter. 7.2 Requirements for Non-machinery Room Spaces. Where an ammonia refrigeration system or equipment is installed outside of a machinery room, the area containing the system or equipment shall comply with this section Separation. The area shall be separated from other occupancies by tight construction with tight-fitting doors Access. Access to the refrigeration equipment shall be restricted to authorized personnel Egress. A means of egress directly to the outdoors, an enclosed exit stairway, or to a horizontal exit or exit passageway complying with the Building Code shall be provided. EXCEPTIONS: 1. Rooms or areas that are 500 ft² or less in area shall not be required to have a means of egress directly to the outdoors. 2. Rooms or areas that are equipped with a fire sprinkler system shall not be required to have a means of egress directly to the outdoors. 3. Where a minimum of 100 ft² (9.3 m²) of floor area is provided for each occupant *Detection and Alarms. Level 1 detection and alarm shall be provided in accordance with Section The detection and alarm system shall comply with Chapter 17. EXCEPTIONS: 1. Unoccupied areas with only continuous piping that does not include valves, valve assemblies, equipment, or equipment connections. 2. Where approved, alternatives to fixed detection systems shall be permitted for rooms or areas in industrial occupancies that are always occupied Physical Protection. Equipment shall be protected where there is a risk of physical damage. Where equipment containing ammonia is located in an area with heavy vehicular traffic during normal operations and there is a risk of impact, vehicle barriers or alternative protection shall be provided in accordance with the Fire Code Temperature Control Ventilation. Where necessary to maintain dry bulb temperature in the area at or below 104 F (40 C), temperature control ventilation shall be provided Environmental Compatibility. Equipment shall be designed to operate in the environmental conditions of the area in which it is to be installed. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 25

39 7.2.8 Illumination. The refrigeration equipment shall be equipped with lighting, or the area with refrigeration equipment shall be equipped with light fixtures delivering a minimum of 30 foot-candles [320 lumens/m2] at the working level, 36 inches (0.91 m) above a floor or platform Service Provisions. Service provisions shall comply with Section Penthouses. Penthouses that are open to an interior space shall be regulated as part of the interior space. Penthouses that are isolated from an interior space shall be regulated as an equipment enclosure in accordance with Section Ventilation Refrigeration Systems and Portions Thereof with a Total Connected Compressor Power Not Exceeding 100 HP (74.6 kw) *Industrial occupancies containing ammonia refrigeration systems or portions thereof with a total connected compressor power not exceeding 100 HP (74.6 kw), located outside of a machinery room in accordance with Section Item 4, shall comply with this section. *Emergency mechanical ventilation shall be in accordance with this section Where the quantity of ammonia in a refrigeration system would yield an ammonia concentration exceeding 40,000 ppm in the in the room or space containing the equipment following a release of the entire charge from the largest independent refrigerant circuit, based on the volume calculation determined in accordance with Section 5.4, emergency ventilation at a rate of 30 air changes per hour shall be provided. EXCEPTION: Where approved, alternatives to emergency mechanical exhaust ventilation of the entire room that will maintain the concentration below 40,000 ppm shall be permitted When calculations performed in accordance with Section 5.4 are used as a basis for omitting emergency mechanical ventilation, the designer shall provide a copy of the calculations to be retained at the site Where an emergency mechanical ventilation system is required, Level 3 ammonia detection and alarm in accordance with Section shall be provided, and the system shall comply with Sections and Emergency detection and alarms shall comply with Chapter Outdoor Systems. Where a refrigeration system or equipment is located outdoors and is enclosed or partially enclosed by a penthouse, lean-to, or other structure, the refrigeration system or equipment shall be located not less than 20 feet from building entrances and exits and natural ventilation shall be provided as follows or mechanical ventilation shall be provided in accordance with Section Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 26

40 The free-aperture cross section for natural ventilation shall be not less than: F = G 0.5 (I-P) F = 0.138G 0.5 (SI) Where: F = the free opening area, ft² (m²) G = the mass of ammonia in the largest independent circuit, any part of which is located within the enclosure or structure, lb (kg) Equipment Pits Located Indoors Where refrigeration equipment containing ammonia is located in an indoor pit that is 5 feet (1.52 m) or more in depth, emergency ventilation at a rate of 30 air changes per hour shall be provided and Level 3 ammonia detection and alarm complying with Section shall be provided. The emergency mechanical exhaust ventilation system shall comply with Sections and Make-up air shall be supplied near the floor of the indoor pit. Air shall be directed toward the equipment and away from the pit exit. Where pit ventilation is arranged to exhaust through a room that is open to the pit, the combined volume of the pit and the room shall serve as the basis for calculating emergency mechanical exhaust ventilation. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 27

41 Part 3 Chapter 8. Equipment Compressors 8.1 General. Ammonia refrigeration compressors shall comply with this chapter. 8.2 Design Pressure. The minimum design pressure shall comply with Section Positive-Displacement Compressor Protection *Where a stop valve is provided in the discharge connection, a positive-displacement compressor shall be equipped with a pressure relief device selected to prevent the discharge pressure from increasing to more than 10% above the lowest of the maximum allowable working pressures of the compressor or any other equipment located in the path between the compressor and the stop valve, or in accordance with Section , whichever is larger. The pressure relief device shall discharge into the low pressure side of the system or in accordance with the requirements of Section for atmospheric discharge. The relief device shall be sized based on compressor flow at a minimum of 50 F (10 C) saturated temperature at the compressor suction or at design saturated suction temperature, whichever is greater. The minimum size compressor pressure vessel relief connection shall be in accordance with Section The area of the opening through piping, fittings, and pressure relief devices, where installed, including 3-way valves for dual reliefs, between a compressor pressure vessel, such as an oil separator, and its pressure relief valve, shall be not less than the area of the pressure relief valve inlet. See Section EXCEPTIONS 1. For compressors capable of operating only when discharging to the suction of a higher-stage compressor, flow shall be calculated at the saturated suction temperature equal to the design operating intermediate temperature. 2. For compressors equipped with automatic capacity regulation which actuates to minimum flow at 90% or below of the pressure-relief device setting and a pressure-limiting device is installed and set in accordance with Section 8.3.2, the discharge capacity of the relief device shall be allowed to be the minimum regulated flow rate of the compressor. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 28

42 8.3.2 *Compressors shall be provided with high-discharge-temperature, low-suction-pressure, and high-discharge-pressure limiting devices to shut-down the compressors when the safe ranges are exceeded. Compressors using forced feed oil lubrication shall be provided with an indicating-type lubrication failure control for low oil pressure shut-down. Except for booster compressors, high-pressure-limiting devices shall be of the manual-reset type. The setting of high-pressure-limiting devices shall not exceed the lower of the compressor manufacturer s recommendation or 90% of the setting of the pressure-relief device on the discharge side of the compressor. The setting of low-pressure-limiting devices shall be the higher of: 1. The system s minimum design pressure to protect against freeze-up or other damage. 2. The compressor manufacturer s recommendations Protection from exposed rotating parts shall be in accordance with Section If rotation is to be in only one direction, a rotation arrow shall be cast in or permanently attached to the compressor frame using an attached label or plate or equivalent means Ultimate strength requirements shall be in accordance with Section Procedures/Testing. Compressors shall be strength tested to a minimum of 1.5 times the design pressure, subsequently leak tested, and proven tight at a pressure not less than design pressure. 8.5 Equipment Identification The following data shall be provided on nameplates or labels affixed to compressors: 1. Manufacturer s name 2. Manufacturer s serial number 3. Manufacturer s model number 4. Year manufactured (encoded with serial number is permissible) 5. Maximum allowable working pressure (MAWP) 6. Maximum rotation speed in rpm 7. Direction of rotation; comply with Section if applicable A compressor without a nameplate per the requirements of Section shall not be used unless the applicable compressor operating limitations have been verified through the identification of the manufacturer and the manufacturer s model number of the compressor from casting numbers or similar positive identification. 8.6 Compressor Installation. Design for compressor installation shall comply with this section Compressors shall have one or more valved pump-out connections for removal of ammonia. Compressors that are packaged with other equipment shall be permitted to have pump-out connections located elsewhere on the package The design shall account for the impact on the compressor if operating in low ambient temperatures, to avoid condensation of ammonia in the compressor package or piping during operation or standby. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 29

43 8.6.3 At a minimum, designs shall include provisions for installing compressor foundations according to manufacturers instructions, grouting, or for installing isolation from the floor or structure of the building, where required Where a variable frequency drive is used to operate a compressor, the manufacturer s instructions shall be followed and the compressor using the variable frequency drive shall be stable at frequencies during its operation. If resonant harmonics are encountered, identified, and cannot be isolated from the system, frequencies shall be permitted to be skipped, if applicable Refrigeration compressors shall be selected to operate within the design limitations specified by the compressor manufacturer *Compressors shall be fitted with a discharge check valve, a suction check valve or both as necessary to avoid backflow of refrigerant and the accumulation of liquid from the condensation of gas in the discharge piping when the compressor is shut down. Other means of avoiding backflow and accumulation of liquid shall be permitted. Stop valves shall be in accordance with Section EXCEPTION: Self-contained systems designed to equalize on shutdown shall not be required to have a suction or discharge check valve Before being applied in a new design, any previously used compressor shall be inspected for signs of alteration, modification, or physical repair that might affect the integrity of the compressor casing. Any compressor integrity issue shall be corrected and verified before operation. Where a compressor casing has been altered, modified or repaired, the casing shall be recertified prior to operation for pressure compliance by the manufacturer or insurance underwriter and recertification papers shall be maintained on site with the refrigeration management program The compressor shall be fitted with pressure and temperature indicating devices, including but not limited to gauges or readouts on a control display screen that allow an observer to visually determine the compressor s suction pressure; discharge pressure; oil pressure, if the compressor uses forced feed lubrication; and discharge temperature *High-liquid Level Alarm. Where a compressor suction line is directly connected to a vessel, the compressor suction line shall be equipped with a sensor to activate an alarm and cause the associated compressors to shut down if a high ammonia liquid level is detected. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 30

44 Chapter 9. Refrigerant Pumps 9.1 General. Refrigerant pumps shall comply with this chapter. 9.2 Design EXCEPTION: Liquid ammonia transfer employing pressure differential to move liquid ammonia, such as pumper drum systems Minimum design pressure shall be in accordance with Section 5.6, or greater where required by a specific application design requiring higher pressure A means of protecting refrigerant pumps and connected piping from hydrostatic overpressure shall be provided. Permissible means of protection shall include, but not be limited to, either: 1) A hydrostatic or differential pressure relief device, or 2) A vent pipe containing a normally-open isolation valve. The inlet connection for the relief device or vent pipe shall be located on the pump casing or piping between the stop valves or stop check valves at the pump inlet and outlet, except that when a check valve is located between the pump and its outlet stop valve, the relief device or vent pipe inlet shall be connected to the pipe between the discharge check valve and stop valve. The discharge of this relief or vent pipe shall connect either to the pump suction line upstream of the pump suction stop valve or to the vessel to which the pump suction is connected. This pressure relief device or vent pipe shall be external to the pump housing Ultimate strength requirements shall be in accordance with Section Protection from exposed rotating parts shall be in accordance with Section Refrigerant pumps shall be suitable for the service in which they are being applied Refrigerant pumps shall be provided with isolation valves Refrigerant pumps shall be installed on a foundation designed for expected loads. 9.3 Procedures/Testing. Refrigerant pumps shall be strength tested to a minimum of 1.5 times the design pressure, subsequently leak tested, and proven tight at a pressure not less than design pressure. 9.4 Equipment Identification. Manufacturers producing refrigerant pumps shall permanently affix a nameplate to the pump providing not less than the following: 1. Manufacturer s name 2. Manufacturer s serial number 3. Manufacturer s model number Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 31

45 9.4.1 Pump data sheet submittals shall include the following information from the manufacturer: 1. Ammonia 2. Operating condition data 3. Performance data 4. Construction data including maximum allowable pressure at operating temperature, test pressure, bearing type, and impeller data 5. Head differential pressure (ft, m, or psi) 6. Impeller identification (diameter size) 7. RPM (Speed) - for fixed-speed pumps and minimum, maximum, & operating RPM s for adjustable speed pumps 8. Capacity (maximum rated gpm or liters/min) with identified impeller 9. Materials metals and gaskets 10. Motor (Driver) information 11. Electric motor ratings if applicable - volts, full load amps (FLA), frequency (Hz), phase, output (HP and/or KW) 12. Electric heater ratings if applicable - volts, amps, phase, output (KW) 13. Insulation classification 14. Piping connections schematic 15. Pump operating procedure description 16. Inspections & tests verification performance and pressure test 17. Minimum Circuit Amps (MCA) and Maximum Over-Current Protection (MOCP) if applicable 18. Weight 19. Direction of rotation - confirmed and documented, Mark or Label a directional arrow on the unit 20. Year manufactured Pumps shall be capable of being pumped out for removal of ammonia. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 32

46 Chapter 10. Condensers 10.1 *General. Condensers shall comply with this chapter Air-Cooled Condensers and Air-Cooled De-superheaters. Tube-and-fin and micro-channel type air-cooled condensers and air-cooled de-superheaters shall comply with this section Design Minimum design pressure shall be in accordance with Section 5.6. Ultimate strength requirements shall be in accordance with Section Where the refrigerant inlet and outlet piping of air-cooled condensers and desuperheaters can be automatically isolated, they shall be protected from hydrostatic overpressure in accordance with Section Protection from exposed rotating parts shall be in accordance with Section Fan speeds shall not exceed the design speed limit recommended by the manufacturer Procedures/Testing. Air-cooled condensers and de-superheaters shall be strength tested to a minimum of 1.1 times the design pressure, subsequently leak tested, and proven tight at a pressure not less than design pressure Equipment Identification. The following data shall be provided on nameplates or labels affixed to equipment: EXCEPTION: Nameplate data is not required on air-cooled de-superheaters that are integral with condensers. 1. Manufacturer s name 2. Manufacturer s serial number 3. Manufacturer s model number 4. Year manufactured 5. Design pressure 6. Direction of fan rotation 7. Electric motor power 8. Electric supply: volts, full load amps, frequency (Hz), phase. 9. At a minimum, if not on the nameplate, the condenser submittal sheets shall have the MDMT (Minimum Design Metal Temperature) Clearances. Air-cooled condensers shall be installed with manufacturer-recommended minimum clearances for position of the units and their respective air inlets and air outlets to avoid short-circuiting and to ensure unobstructed air flow Design for Ambient Temperature. Shell-and-tube condensers shall be designed for the range of ambient temperatures at the installed location. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 33

47 10.3 Evaporative Condensers. Evaporative condensers shall comply with this section Design Minimum design pressure shall be in accordance with Section 5.6. Ultimate strength requirements shall be in accordance with Section Pressure vessels incorporated into evaporative condensers shall comply with Chapter 12. Where the refrigerant coil inlet and outlet piping of evaporative condensers can be automatically isolated, the condenser shall be protected from refrigerant hydrostatic overpressure in accordance with Section Protection from exposed rotating parts shall be in accordance with Section Fan speeds shall not exceed the design speed limit recommended by the manufacturer. Evaporative condensers shall be adequately anchored and supported Procedures/Testing Evaporative condensers shall be strength tested to a minimum of 1.1 times the design pressure, subsequently leak tested, and proven tight at a pressure not less than design pressure Equipment Identification The following data shall be provided on nameplates or labels affixed to equipment: 1. Manufacturer s name 2. Manufacturer s serial number 3. Manufacturer s model number 4. Year manufactured 5. Design pressure 6. Direction of fan rotation, and water circulating pump, if supplied 7. Electric motor rating for fans, and water circulating pump, if supplied 8. Electric supply: volts, full load amps, frequency (Hz), phase Clearances. Evaporative condensers shall be installed with manufacturer-recommended minimum clearances for position of the units and their respective air inlets and air outlets to avoid short-circuiting and to ensure unobstructed air flow Freeze Protection. Freeze protection shall be provided as needed for the sump and water piping Drainage of Overflow and Waste Water. Drainage of overflow and waste water shall be provided, as needed. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 34

48 Design for Ambient Temperature. Shell-and-tube condensers shall be designed for the range of ambient temperatures at the installed location Shell-and-Tube Condensers. Shell-and-tube condensers shall comply with this section. Equipment covered by this section includes horizontal and vertical shell-and-tube condensers with closed water passes and vertical shell-and-tube condensers with open water passes Design Minimum design pressure shall be in accordance with Section 5.6. Secondary coolant side ultimate strength requirements shall be in accordance with Section Pressure vessels incorporated into shell-and-tube condensers shall comply with Chapter 12. Where the refrigerant inlet and outlet piping of shell-and-tube condensers can be isolated, the refrigerant side shall be pressure-relief protected in accordance with Section EXCEPTION: Where the condenser is not a pressure vessel, the condenser shall be protected from hydrostatic overpressure in accordance with Section Where the secondary coolant inlet and outlet piping of shell-and-tube condensers can be automatically isolated, protection from hydrostatic overpressure shall be in accordance with Section Procedures/Testing. Shell-and-tube condensers shall be tested in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent, if applicable, but at a minimum, shall be strength tested to a minimum of 1.1 times the design pressure, subsequently leak tested, and proven tight at a pressure not less than design pressure. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 35

49 Equipment Identification. Manufacturers producing shell-and-tube condensers shall provide the following minimum data on a nameplate affixed to the equipment: 1. ASME stamp, where applicable 2. National Board Number, where applicable 3. Manufacturer s name, preceded by the words certified by on nameplates of integral ASME-stamped vessels 4. Shell-side maximum allowable working pressure (MAWP) at temperature 5. Tube-side maximum allowable working pressure (MAWP) at temperature 6. Shell-side minimum design metal temperature (MDMT) at pressure 7. Tube-side minimum design metal temperature (MDMT) at pressure 8. Manufacturer s serial number 9. Manufacturer s model number, where applicable 10. Year manufactured 11. Type of construction in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent, where applicable. Manufacturers producing shell-and-tube condensers with integral pressure vessels, such as condensers with refrigerant in a shell qualifying as a pressure vessel, shall provide data in accordance with the relevant UG sections of ASME B&PVC, Section VIII, Division 1 or international equivalent Shell-and-Tube Condenser Installation Considerations Clearance shall be provided as necessary to accommodate maintenance or replacement of the condenser tubes. Shell-and-tube condensers shall be designed for the range of ambient temperatures at the installed location Plate Heat Exchanger Condensers. Plate heat exchanger condensers shall comply with this section. Equipment covered by this section includes plate heat exchanger condensers of the plateand-shell type and of the plate-and-frame type Design Minimum design pressure shall be in accordance with Section 5.6. Ultimate strength requirements shall be in accordance with Section Pressure vessels incorporated into plate heat exchanger condensers, such as the shell of a plate-and-shell condenser with refrigerant in a shell qualifying as a pressure vessel, shall comply with Chapter 12. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 36

50 Where the refrigerant inlet and outlet piping of ammonia-containing plate packs can be isolated, the ammonia side of the plate pack shall be pressure-relief protected in accordance with Section EXCEPTION: Where the condenser is not a pressure vessel, it shall be protected from hydrostatic overpressure in accordance with Section Where the non-refrigerant process fluid inlet and outlet lines of plate packs can be automatically isolated, they shall be protected from hydrostatic overpressure in accordance with Section Procedures/Testing. Plate heat exchanger condensers shall be tested in accordance with ASME B&PVC Section VIII, Division 1 or international equivalent, if applicable, but at a minimum, shall be strength tested to a minimum of 1.1 times the design pressure, subsequently leak tested, and proven tight at a pressure not less than design pressure Equipment Identification. Manufacturers producing plate heat exchanger condensers shall provide the following minimum data on a nameplate affixed to the equipment. 1. ASME stamp, where applicable 2. National Board Number, where applicable 3. Manufacturer s name, preceded by the words certified by, if the heat exchanger is ASME-stamped 4. Hot-side maximum allowable working pressure (MAWP) at temperature, where applicable 5. Cold-side maximum allowable working pressure (MAWP) at temperature 6. Hot-side minimum design metal temperature (MDMT) at pressure, where applicable 7. Cold-side minimum design metal temperature (MDMT) at pressure 8. Manufacturer s serial number 9. Manufacturer s model number, where applicable 10. Year manufactured 11. Test pressure, note test type; hydraulic or pneumatic 12. Type of construction (in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent, where applicable) Manufacturers producing plate heat exchanger condensers with integral pressure vessels, such as plate-and-shell heat exchangers with refrigerant in a shell qualifying as a pressure vessel, shall provide data in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent Plate Heat Exchanger Condenser Installation Considerations. Clearance shall be provided as necessary to accommodate removal and replacement of the condenser plates if this service is to be done in the installed location. Plate heat exchanger type condensers shall be designed for the range of ambient temperatures at the installed location. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 37

51 10.6 Double-Pipe Condensers. Double-pipe condensers shall be in accordance with this section. Equipment covered by this section is double-pipe condensers with closed-water passes Design. Minimum design pressure shall be in accordance with Section 5.6. Secondary coolant side ultimate strength requirements shall be in accordance with Section Pressure vessels incorporated into double-pipe condensers shall comply with Chapter 12. Where the refrigerant inlet and outlet piping of double-pipe condensers can be isolated, the refrigerant side shall be pressure-relief protected in accordance with Section EXCEPTION: Where the condenser is not a pressure vessel it shall be protected from hydrostatic overpressure in accordance with Section Where the secondary-coolant inlet and outlet piping of double-pipe condensers can be automatically isolated, they shall be protected from hydrostatic overpressure in accordance with Section Procedures/Testing. Double-pipe condensers shall be tested in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent, if applicable, but at a minimum, shall be strength tested to a minimum of 1.1 times the design pressure, subsequently leak tested, and proven tight at a pressure not less than design pressure Equipment Identification Manufacturers producing double-pipe condensers shall provide the following minimum data on a nameplate affixed to the equipment: 1. ASME stamp, where applicable 2. National Board Number, where applicable 3. Manufacturer s name, preceded by the words certified by on nameplates of integral ASME-stamped vessels 4. Shell-side maximum allowable working pressure (MAWP) at temperature 5. Tube-side maximum allowable working pressure (MAWP) at temperature 6. Shell-side minimum design metal temperature (MDMT) at pressure 7. Tube-side minimum design metal temperature (MDMT) at pressure 8. Manufacturer s serial number 9. Manufacturer s model number, where applicable 10. Year manufactured Type of construction in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent, where applicable. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 38

52 Manufacturers producing double-pipe condensers with integral pressure vessels, such as condensers with refrigerant in a shell qualifying as a pressure vessel, shall provide data in accordance with the relevant UG sections of ASME B&PVC, Section VIII, Division 1 or international equivalent Double-Pipe Condenser Installation Considerations. Clearance shall be provided as necessary to accommodate removal and replacement of condenser pipes if this service is to be done in its installed location. Double-Pipe condensers shall be designed for the range of ambient temperatures at the installed location. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 39

53 Chapter 11. Evaporators 11.1 General. Evaporator coils and micro-channel heat exchangers shall comply with this chapter Forced-Air Evaporator Coils Design Minimum design pressure shall be in accordance with Section 5.6. Ultimate strength shall be in accordance with Section Where refrigerant coil inlet and outlet lines can be automatically isolated, they shall be protected from hydrostatic overpressure in accordance with Section Protection from exposed rotating parts shall be in accordance with Section Fan speeds shall not exceed the design speed limit recommended by the manufacturer. Pressure vessels coupled to evaporators shall comply with Chapter Procedures/Testing. Evaporator coils shall be strength tested to a minimum of 1.1 times the design pressure, subsequently leak tested, and proven tight at a pressure not less than design pressure Equipment Identification. The following data shall be provided on nameplates or labels affixed to equipment: 1. Manufacturer s name 2. Manufacturer s serial number 3. Manufacturer s model number 4. Year manufactured 5. Design pressure 6. Direction of fan rotation, if supplied 7. Electric motor size for fans, if supplied 8. Electric defrost heater and drain pan heater ratings, as applicable 9. Electric supply: volts, full load amps, frequency (Hz), phase 10. Minimum Design Metal Temperature (MDMT), if applicable, or at a minimum, submitted with the equipment manufacturer s data sheets Installation Considerations. Manufacturer s recommended clearances for unobstructed airflow at the inlet and outlet of the forced-air evaporator shall be provided. A means for preventing freezing inside condensate drain lines, such as but not limited to slope to drain, heat tracing, insulation, or clean-outs, shall be provided where lines are exposed to freezing temperatures. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 40

54 11.3 Shell-and-Tube Evaporators Shell-and-Tube Evaporators with ammonia in shell. Shell-and-tube evaporators shall comply with this section. Design Minimum design pressure shall be in accordance with Section Pressure vessels coupled to shell-and-tube evaporators shall comply with Chapter Where the tube-side inlet and outlet lines of shell-and-tube evaporators with the refrigerant in the shell are automatically isolated, the tube-side shall be protected from hydrostatic overpressure in accordance with Section Procedures/Testing. Shell-and-tube evaporators shall be tested in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent, where applicable, but at a minimum, shall be strength tested to a minimum of 1.1 times the design pressure, subsequently leak tested, and proven tight at a pressure not less than design pressure. Equipment Identification. Manufacturers producing shell-and-tube evaporators for refrigerant in the shell shall provide data in accordance with the relevant UG sections of ASME B&PVC, Section VIII, Division 1 or international equivalent, but in any case shall provide the following minimum data on a nameplate affixed to the equipment: 1. ASME stamp, where applicable 2. National Board Number, where applicable 3. Manufacturer s name, preceded by the words certified by, if the vessel is ASME-stamped 4. Shell side maximum allowable working pressure (MAWP) at temperature 5. Tube side maximum allowable working pressure (MAWP) at temperature 6. Shell side minimum design metal temperature (MDMT) at pressure 7. Tube side minimum design metal temperature (MDMT) at pressure 8. Manufacturer s serial number 9. Manufacturer s model number, where applicable 10. Year manufactured 11. Test pressure, note test type; hydraulic or pneumatic 12. Type of construction (in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent, where applicable Installation Considerations. Installation considerations shall be in accordance with Section Shell-and-Tube Evaporators with ammonia in tubes. Shell-and-tube evaporators shall be in accordance with this section. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 41

55 Design Minimum design pressure shall be in accordance with Section Pressure Vessels coupled to shell-and-tube evaporators with ammonia in the tubes shall comply with Chapter Where the tube-side inlet and outlet lines of shell-and-tube evaporators, with ammonia in tubes, can be isolated, the tube-side shall be hydrostatic overpressure-relief protected in accordance with Section EXCEPTION: Where the tube-side of the evaporator is built and stamped in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent, it shall protected from overpressure in accordance with Section The tube-side shall comply with ASME B31.5 Section 5, ASME B&PVC, Section VIII, Division 1 or international equivalent Heat loads from cleaning operations and process loads shall be considered when designing the relief capacity and control of process heat exchangers. Procedures/Testing. Shell-and-tube evaporators shall be tested in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent, if applicable, but at a minimum, shall be strength tested to a minimum of 1.1 times the design pressure, subsequently leak tested, and proven tight at a pressure not less than design pressure. Equipment Identification. Manufacturers producing shell-and-tube evaporators for refrigerant in the tubes shall provide the data in accordance with the relevant UG section of ASME Boiler and Pressure and Vessel Code, Section VIII, Division 1 or international equivalent, where applicable, and in any case shall provide the following minimum data on a nameplate affixed to the equipment: 1. ASME stamp, where applicable 2. National Board Number, where applicable 3. Manufacturer s name,(preceded by the words certified by, if the vessel is ASME-stamped 4. Shell side maximum allowable working pressure (MAWP) at temperature 5. Tube side maximum allowable working pressure (MAWP) at temperature 6. Shell side minimum design metal temperature (MDMT) at pressure 7. Tube side minimum design metal temperature (MDMT) at pressure 8. Manufacturer s serial number 9. Manufacturer s model number, where applicable 10. Year manufactured 11. Test pressure, note test type; hydraulic or pneumatic 12. Type of construction, in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent, where applicable Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 42

56 Installation Considerations Clearance shall be provided for the maintenance or replacement of evaporator tubes The ambient temperatures in the area the shell-and-tube evaporator is installed shall be considered in the design of the secondary-coolant side of the evaporator Plate Heat Exchanger Evaporators. Plate heat exchanger evaporators shall comply with this section. Equipment covered by this section includes plate heat exchanger evaporators of the plateand-shell type, and of the plate-and-frame type in which the heat transfer plate stack is axially contained between two pressure plates and where the plate joints may be fully elastomeric, paired plate sets welded with adjacent sets elastomeric, fully welded, or fully nickel brazed Design Minimum design pressure shall be in accordance with Section 5.6. Ultimate strength requirements shall be in accordance with Section Pressure vessels coupled to plate heat exchanger evaporators, such as plate-and-shell designed with the ammonia in a shell qualifying as a pressure vessel, shall comply with Chapter 12. Where the refrigerant inlet and outlet lines of ammonia-containing plate packs can be isolated, the ammonia side of the plate pack shall be overpressure-relief protected in accordance with Section EXCEPTION: Where the evaporator is not a pressure vessel, it shall be protected from hydrostatic overpressure in accordance with Section Where the non-refrigerant process fluid inlet and outlet lines of plate packs can be isolated, they shall be protected from hydrostatic overpressure in accordance with Section 15.6 on the process side. Heat loads from cleaning operations or process loads shall be considered when designing the relief capacity and control of process heat exchangers Procedures/Testing. Plate heat exchanger evaporators shall be tested in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent, if applicable, but a minimum, shall be strength tested to a minimum of 1.1 times the design pressure, subsequently leak tested, and proven tight at a pressure not less than design pressure. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 43

57 Equipment Identification. Manufacturers producing plate heat exchanger evaporators shall provide the following minimum data on a nameplate affixed to the equipment: 1. ASME stamp, where applicable 2. National Board Number, where applicable 3. Manufacturer s name, preceded by the words certified by, if the vessel is ASME-stamped 4. Hot-side maximum allowable working pressure (MAWP) at temperature, where applicable 5. Cold-side maximum allowable working pressure (MAWP) at temperature 6. Hot-side minimum design metal temperature (MDMT) at pressure, where applicable 7. Cold-side minimum design metal temperature (MDMT) at pressure 8. Manufacturer s serial number 9. Manufacturer s model number, where applicable 10. Year manufactured 11. Test pressure, note test type; hydraulic or pneumatic 12. Type of construction, in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent where applicable Manufacturers producing plate heat exchanger evaporators incorporating pressure vessels (e.g., plate-and-shell evaporators with ammonia in a shell qualifying as a pressure vessel) shall provide data in accordance with the UG section of ASME B&PVC, Section VIII, Division 1 or international equivalent, where applicable Installation Considerations. Clearance shall be provided for maintenance or replacement of evaporator plates. The ambient temperatures in the area the plate heat exchanger evaporator is installed shall be considered in the design of the secondary-coolant side of the evaporator Scraped (Swept) Surface Heat Exchangers. Scraped (swept) surface heat exchangers shall comply with this section Design Minimum design pressure shall be in accordance with Section 5.6. Pressure vessels coupled to scraped (swept) surface heat exchangers shall comply with Chapter 12. Heat loads from cleaning operations or process loads shall be considered when designing the relief capacity and control of scraped surface heat exchangers. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 44

58 Procedures/Testing. Scraped (swept) surface heat exchangers shall be tested in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent, if applicable, but at a minimum, shall be strength tested to a minimum of 1.1 times the design pressure, subsequently leak tested, and proven tight at a pressure not less than design pressure Equipment Identification. Manufacturers producing scraped (swept) surface heat exchangers for refrigerant in the shell shall provide data in accordance with the relevant UG sections of ASME B&PVC, Section VIII, Division 1 or international equivalent, but in any case shall provide the following minimum data on a nameplate affixed to the equipment: 1. ASME stamp, where applicable 2. National Board Number, where applicable 3. Manufacturer s name, preceded by the words certified by, if the vessel is ASMEstamped 4. Shell maximum allowable working pressure (MAWP) at temperature 5. Shell minimum design metal temperature (MDMT) at pressure 6. Manufacturer s serial number 7. Manufacturer s model number, where applicable 8. Year manufactured 9. Test pressure, note test type; hydraulic or pneumatic) 10. Type of construction, in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent, where applicable Installation Considerations. Clearance shall be provided for the maintenance or replacement of equipment. The ambient temperatures in the area the scraped (swept) surface heat exchanger is installed shall be considered in the design Jacketed Tanks. Jacketed tanks shall comply with this section Design Minimum design pressure shall be in accordance with Section 5.6. Ultimate strength requirements shall be in accordance with Section Pressure vessels coupled to jacketed tanks evaporators shall comply with Chapter 12. Where the refrigerant inlet and outlet lines of the jacketed tank ammonia-containing evaporator can be isolated, the ammonia side of the evaporator shall be overpressurerelief protected in accordance with Section EXCEPTION: Where the jacketed tank evaporator is not a pressure vessel, it shall be protected from hydrostatic overpressure in accordance with Section Heat loads from cleaning operations or process loads shall be considered when designing the relief capacity and control of jacked tanks. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 45

59 Procedures/Testing. Jacketed tanks shall be tested in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent, if applicable, but at a minimum, shall be strength tested to a minimum of 1.1 times the design pressure, subsequently leak tested, and proven tight at a pressure not less than design pressure Equipment Identification. Manufacturers producing jacketed tanks shall provide the following minimum data on a nameplate affixed to the equipment: 1. ASME stamp, where applicable 2. National Board Number, where applicable 3. Manufacturer s name, preceded by the words certified by, if the vessel is ASME-stamped 4. Maximum allowable working pressure (MAWP) at temperature, where applicable 5. Minimum design metal temperature (MDMT) at pressure, where applicable 6. Manufacturer s serial number 7. Manufacturer s model number, where applicable 8. Year manufactured 9. Test pressure, note test type; hydraulic or pneumatic 10. Type of construction, in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent, where applicable Manufacturers producing jacketed tanks incorporating pressure vessels, such as plateand-shell evaporators with ammonia in a shell qualifying as a pressure vessel, shall provide data in accordance with the UG section of ASME B&PVC, Section VIII, Division 1 or international equivalent, where applicable Installation Considerations. The ambient temperatures in the area the jacketed tank is installed shall be considered in the design. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 46

60 Chapter 12. Pressure Vessels 12.1 General. Pressure vessels shall comply with this chapter Design Minimum design pressure shall be in accordance with Section 5.6. EXCEPTION: Where ammonia liquid is to be transferred from pressure vessels by pressurized ammonia gas, the pressure vessel design pressure shall accommodate the maximum possible transfer pressure and take into account the lowest possible coincident metal temperature Pressure vessels exceeding 6 in [15 cm] inside diameter shall comply with ASME B&PVC, Section VIII, Division 1 or international equivalent covering the requirements for design, fabrication, inspection and testing during construction of unfired pressured vessels. Pressure vessels having inside diameters less than 6 in [15 cm] shall require ultimate strength in accordance with Section For vessels larger than 6 [15.24 cm] inside diameter but less than 10 cubic feet [0.28 m³] in internal volume, the pressure relief valve connection shall not be less than ¾ [1.91 cm] piping or a ½ [1.27 cm] coupling. For vessels with an internal volume of 10 cubic feet [0.28 m³] or larger, the pressure relief valve connection shall not be less than 1 [2.54 cm] piping or a ¾ [1.91 cm] coupling Pressure vessels shall be provided with one or more openings for the attachment of pressure relief devices, as required by Section The heads of pressure vessels shall be hot-formed or stress relieved after cold-forming. EXCEPTION: Vessels primarily containing oil, including but not limited to oil separators, oil filters, oil coolers and oil pots *The designer shall specify whether pressure vessels are required to be treated to prevent stress corrosion cracking A vessel shall be designed and stamped with a minimum design metal temperature no higher than its lowest expected operating temperature In applications where pressure vessels are subject to external corrosion as determined by the owner or his designated agent, the vessels shall be designed and specified with a minimum of 1/16" [1.6 mm] corrosion allowance. The external corrosion allowance is in addition to the minimum vessel thickness as required by ASME B&PVC, Section VIII, Division 1 or international equivalent. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 47

61 Pressure vessel shall be piped for compliance with the pressure and temperature limitations specified on the name plate data Alterations to pressure vessels shall be allowed only as directed by the AHJ. The alterations shall only be performed by a qualified service approved by the AHJ. A re-stamping shall be applied as required by the AHJ when the modification is completed Procedures/Testing. Pressure vessels shall be tested in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent, if applicable, but at a minimum, shall be strength tested hydrostatically to a minimum of 1.3 times the design pressure or air tested to a minimum of 1.1 times the design pressure, subsequently leak tested, and proven tight at a pressure not less than design pressure Equipment Identification Manufacturers producing pressure vessels shall provide data in accordance with the requirements of the relevant UG sections of ASME B&PVC, Section VIII, Division 1 or international equivalent, but in any case shall provide the following minimum data on a nameplate affixed to the equipment as specified in Section : 1. ASME stamp, where applicable 2. National Board Number, where applicable 3. Manufacturer s name, preceded by the words certified by, if the vessel is ASME stamped 4. Maximum allowable working pressure (MAWP) at temperature 5. Minimum design metal temperature (MDMT) at pressure 6. Manufacturer s serial number 7. Year of manufacture 8. Manufacturer s model number, where applicable 9. Type of construction, in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent, where applicable 10. A stamp shall be affixed to the equipment that includes the minimum design metal temperature (MDMT) that it is operated at in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent Nameplate Mounting Nameplates shall comply with Section If any pressure vessel is insulated, the name plate shall be mounted on an approved stand-off so it is not covered or the insulation at the nameplate location on the pressure vessel shall be removable to allow for name plate inspection. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 48

62 12.5 Pressure Vessel Installation Considerations Clearance shall be provided for maintenance Physical protection shall comply with Section Pressure vessels supported from the ground shall rest on a concrete or other foundation or shall come with a support for sitting directly on and anchoring to the foundation. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 49

63 Chapter 13. Piping 13.1 *General. Piping shall comply with this chapter. The design, fabrication, examination, and testing of the piping, whether fabricated in a shop or as a field erection, shall comply with ASME B31.5, unless otherwise provided by this chapter Pipe, Tubing, Fittings, and Flanges *Material. Piping materials shall comply with ASME B31.5 except as specified in this section. ASTM A53-Type F pipe and cast iron or wrought iron pipe shall not be used for closed-circuit ammonia refrigeration systems. Zinc, copper, and copper alloys shall not be used in contact with or for containment of ammonia. Copper-containing anti-seize and/or lubricating compounds shall not be used in ammonia piping joints *Minimum Pipe Wall Thickness. Minimum pipe wall thickness shall be based on the properties of the selected pipe material, the design working pressure and shall comply with the requirements of ASME B31.5. EXCEPTIONS: 1. Carbon and stainless steel threaded pipe shall be minimum Schedule 80 for all sizes. 2: Carbon steel pipe inch and smaller shall be minimum Schedule Stainless steel pipe inch and smaller shall be minimum Schedule *Minimum Tubing Wall Thickness Pipe Fittings Minimum tubing wall thickness shall be based on the properties of the selected material and the greater of the design working pressure or the requirement specified by the manufacturer of the compression ferrule used for the fitting connection. The use of carbon steel tubing and compression fittings shall be limited to compressors, compressor packages, and packaged systems. Butt weld fittings shall match pipe schedules. EXCEPTION: The schedule of butt weld fittings joining pipe at a wall thickness change shall match the schedule of the thicker wall pipe. The internal diameter of the end of the fitting connecting to the thinner wall pipe shall be machined or ground to match. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 50

64 Pipe Flanges All socket weld and screwed fittings shall be minimum Class 3000 and manufactured from forged or cast steel. Threaded joints shall not be used for refrigerant piping larger than 2 inches in diameter. Threaded piping shall be minimum Schedule 80. Flanges in accordance with ANSI ASME Standard B16.5 shall comply with the requirements of ASME B31.5, be raised face type and the flange class shall be based on the design working pressure and the maximum working temperature at the design working pressure. Gaskets shall be correctly dimensioned for the flange set *Refrigerant Valves and Strainers. Valves used in ammonia-containing and lubricant-containing service shall comply with this section. EXCEPTIONS: 1. Valves within the ammonia-containing envelope of other equipment, such as slide valves in screw compressors. 2. Safety relief valves Required Shut-off Valve Locations. Shut-off valves shall be installed in the refrigerant piping at the following locations: 1. At the inlet and outlet of a positive-displacement-type compressor, compressor unit, or condensing unit. 2. At the main feed inlets and outlets of individual refrigeration equipment loads. 3. At the refrigerant inlet and outlet of a pressure vessel containing liquid ammonia and having an internal gross volume exceeding three (3) cubic feet (0.085 cubic meters). EXCEPTIONS: 1. In lieu of providing shut-off valves at each piece of serviceable equipment, packaged systems and portions of built-up systems shall be permitted to have pump-down arrangements that permit the safe removal or isolation of ammonia for servicing one or more pieces of equipment. 2. Shut-off valves are not required between a refrigeration equipment load and a pressure vessel containing liquid ammonia where a single load is piped into a single pressure vessel, such as a surge-fed evaporator piped into a surge drum. 3. Packaged systems that incorporate subsystem isolation valves shall not require more than one shut-off valve on each ammonia-containing pipe connecting any two parts of a system. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 51

65 Valves in Equipment and System Design Where the manufacturer s specifications indicate that a particular vertical, horizontal or rotational orientation is required for proper operation of a valve, the system design shall indicate the required orientation. EXCEPTION Where the system design provides for a valve to be installed with a different orientation. *Where a valve is deliberately specified for use with the directional indicator marked by the manufacturer being opposite of the normal direction of flow, the system design shall specify the intended installation direction. Valve gasket materials shall match valve manufacturer s specifications and be of the thickness specified * Where a check valve is installed upstream of other automatic valves, pressure relief shall be provided. Provision for liquid removal to facilitate maintenance shall be located downstream of the check valve. Hydrostatic overpressure protection shall comply with Section Strainers shall be fitted with provision for ammonia removal to facilitate maintenance *Shut-off valves used to isolate equipment or devices from other portions of the system for the purpose of maintenance or repair shall be capable of being locked out Shut-off valves connecting ammonia-containing equipment or piping to atmosphere shall be capped, plugged, blanked, or locked closed during shipping, testing, operating, servicing, or standby conditions when they are not in use, in accordance with IIAR Valves required for system emergency shutdown procedures shall be readily accessible and identified in accordance with Sections and Other valves shall be accessible in accordance with Section if installed in a machinery room *Piping, Hangers, Supports Isolation *Piping hangers and supports shall carry the weight of the piping and any additional expected loads Refrigerant piping shall be isolated and supported to prevent damage from vibration, stress, corrosion and physical impact Sway bracing shall be included required by the Building Code Threaded hot rolled steel hanger rods shall be permitted Anchors, their attachment points and attachment methods shall designed to support applied loads Mechanically expanded concrete anchor bodies shall not be adjusted or axially spun after being set. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 52

66 For piping that is insulated, supports shall be designed or the insulation shall be selected to avoid damage to the insulation from compression *Location of Refrigerant Piping Refrigerant piping crossing walkway areas in a building shall be not be less than 7.25 feet (2.2 m) above the floor. EXCEPTION: Where approved, piping shall be permitted to be located less than7.25 feet (2.2 m) above the floor provided that it is placed against the ceiling of such space Refrigerant piping shall not obstruct a means of egress Refrigerant piping shall not be placed in an elevator shaft, dumbwaiter shaft, or other shaft containing a moving object Refrigerant piping shall not be installed in a stair, landing, or means of egress that is enclosed and is accessible to the public Refrigerant piping shall be permitted to be installed underground provided that the piping is protected from corrosion Refrigerant piping installed in concrete floors shall be encased in pipe duct. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 53

67 Chapter 14. Packaged Systems and Equipment 14.1 General Packaged systems and equipment shall comply with this chapter. Such packages shall be permitted to be enclosed or unenclosed. Equipment enclosures shall comply with Section Packaged systems and equipment shall be designed, constructed and installed in accordance with the applicable provisions of Chapter 4 through Chapter *Packaged systems shall be ventilated based on the intended operation of the equipment, as specified by the manufacturer. In addition, emergency mechanical ventilation shall be provided where required by any of the following: 1. Package systems located in machinery rooms shall be included as machinery room equipment. Emergency ventilation for machinery rooms shall be in accordance with Section Package systems located indoors and outside of a machinery room in accordance with Section Item 4, shall comply with Section Package systems located outside that are designed for human occupancy shall comply with Section Package systems located outside that are not designed for human occupancy shall not require ventilation Equipment and devices incorporated into packaged systems shall comply with the applicable provisions of Chapter 8 through Chapter Design The structure of the package shall be designed to support the operating weight of included equipment The structure of the package shall be designed to withstand the stresses caused by shipping and rigging. Temporary supports and bracing shall be permitted. Rigging instructions shall be provided to accommodate the install of the structure The structure of the package shall be designed to withstand loads or stresses that will be imposed on the package after installation and start-up, including environmental factors such as snow, ice, wind, and seismic forces Packaged equipment shall have valved pump-out connections for removal of ammonia Packages shall be designed for use in the lowest expected ambient temperatures in which they will operate Packages shall be designed for use in the highest expected ambient temperatures in which they will operate *Access shall be provided for manually operated valves. Isolation valves identified as being part of a system emergency shutdown procedures shall be directly operable or chain-operated from a permanent work surface. Valve tagging shall comply with Section Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 54

68 Pipes shall be marked in accordance with Section Equipment shall be labeled in accordance with Section Packages shall be equipped with lighting, or the area with refrigeration equipment shall be equipped with light fixtures delivering a minimum of 30 foot-candles [320 lumens/m2] at the working level, 36 inches (0.91 m) above a floor or platform Enclosed packages that require entrance for service, maintenance, inspection or operation shall have lighting control located at entrances Fabrication EXCEPTION: Where continuous lighting exists, the lighting control does shall not be required to be located at the entrances Equipment shall be set on the package in accordance with the manufacturer s recommendations, including proper support and clearances Equipment and piping shall be supported to withstand transporting and rigging. Temporary supports and bracing shall be permitted Stationary or temporary rigging points shall be provided as required to position the package Piping shall be pressure tested after fabrication, and leaks shall be repaired. The package shall be shipped with a holding charge of dry nitrogen or provided with another means approved by the manufacturer to allow validation that leakage has not occurred during shipping or subsequent storage prior to installation Electrical equipment and wiring shall be installed in accordance with the Electric Code Gas fuel devices and equipment used with refrigeration systems in the package shall be installed in accordance with Mechanical Code Alarms and Detection. Detection and alarms for packaged systems shall comply with the following. Where required, the detection and alarm system shall comply with Chapter Package systems located in machinery rooms shall be included as machinery room equipment. Detection and alarms shall be comply with Section Package systems located indoors and outside of a machinery room, as permitted by Section 4.2, shall be provided with Level 2 detection and alarms in accordance with Section Package systems located outdoors that are not intended for human occupancy shall not require ammonia detection or alarms. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 55

69 Chapter 15. Overpressure Protection Devices 15.1 *General. Pressure relief devices provided for the purpose of relieving excess pressure due to fire or other abnormal conditions shall comply with this Chapter *Pressure Relief Devices Refrigeration system shall be protected by not less than one pressure relief device Pressure relief devices provided for vessels constructed in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent shall comply with that code or equivalent and other applicable requirements of this Standard The system design shall specify that pressure relief devices is accessible for inspection and repair *Pressure relief devices intended for vapor service shall be connected above the highest anticipated liquid ammonia level. EXCEPTIONS: 1. Hydrostatic overpressure relief protection shall comply with Section The connection to oil drain pot vessels and similar applications, connect shall be at the highest point Where relief valves are located in refrigerated spaces, precautions shall be taken to prevent moisture migration into the valve body or relief vent line The seats and discs of pressure-relief devices shall be constructed of material that resists ammonia corrosion and other chemical action caused by the ammonia. Seats and discs shall be limited in distortion, by pressure or other cause, to a set pressure change of not more than 5% from the set pressure relief Setting of Pressure Relief Devices The set pressure for a pressure relief valve shall not exceed the design pressure of equipment protected by the valve. The set pressure of a rupture member used in series with a relief valve shall not exceed the design pressure of the equipment protected by the rupture member. *Provision shall be made to detect pressure build up between the rupture member and the relief valve due to leakage through the upstream relief device Marking of Relief Devices Pressure relief valves for ammonia-containing equipment shall be set and sealed by the manufacturer. Pressure relief valves shall be marked by the manufacturer with the data required in ASME B&PVC, Section VIII, Division 1 or international equivalent. Resetting of a pressure relief valve shall be performed by the manufacturer or a company holding a valid testing certificate for this work. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 56

70 15.3 Pressure Relief Protection The capacity in SCFM [m 3 /s] or in lb air/min [kg air/min] shall be stamped on valves or available on request. Rupture members for ammonia-containing pressure vessels shall be marked with the data required in ASME B&PVC, Section VIII, Division 1 or international equivalent Pressure vessels and other types of equipment built and stamped in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent shall be provided with pressure relief protection Pressure vessels intended to operate completely filled with liquid ammonia and that are capable of being isolated by stop valves from other portions of a refrigeration system shall be protected with a certified hydrostatic service relief device as required by ASME B&PVC Section VIII, Division 1 or international equivalent. Hydrostatic overpressure relief shall comply with Section Pressure relief devices shall be sized in accordance with Section Pressure vessels less than 10 ft 3 [0.3 m 3 ] internal gross volume shall be protected by one or more pressure relief devices Pressure vessels of 10 ft 3 [0.3 m 3 ] or more internal gross volume shall be protected by one or more of the following: 1. One or more dual pressure relief devices installed with a three-way valve to allow testing or repair. Where dual relief valves are used, each valve shall comply with Section Dual relief valves shall be set to a fully seated position, with one side open and one side closed. Where multiple dual relief valve assemblies are used, the sum of the capacities of the pressure relief devices actively protecting the vessel shall be required to equal or exceed the requirements set forth in Section A single pressure relief device, provided that: 1) The vessel can be isolated and pumped out; 2) The relief valve is located on the low side of the system; and 3) Other pressure vessels in the system shall be separately protected in accordance with Section Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 57

71 Where pressure relief valves are discharged into other portions of the refrigeration system, the portion of the system receiving the internal discharge shall be equipped with pressure relief devices capable of discharging the increased capacity in accordance with Section and the pressure relief valves discharging into the system shall be with one of the following types: 1. A pressure relief valve not appreciably affected by back pressure, or 2. A pressure relief valve affected by back pressure, in which case the valve s set pressure added to the set pressure of the system pressure relief device shall not exceed the maximum allowable working pressure of any equipment being protected and shall comply with the following: 2.1. The pressure relief valve that protects the higher pressure vessel shall be selected to deliver capacity in accordance with Section without exceeding the minimum design pressure of the higher pressure vessel accounting for the change in mass flow capacity due to the elevated back pressure The capacity of the pressure relief valve protecting the part of the system receiving a discharge from a pressure relief valve protecting a higher pressure vessel shall be at least the sum of the capacity required in Section plus the mass flow capacity of the pressure relief valve discharging into that part of the system The design pressure of the body of the relief valve used on the higher pressure vessel shall be rated for operation at the design pressure of the higher pressure vessel in both pressure containing areas of the valve. EXCEPTION: Where hydrostatic overpressure protection relief devices are discharged into other portions of a refrigeration system that are protected by pressure relief devices design to relieve vapor in accordance with Section 15.3, the capacity of the hydrostatic overpressure protection relief devices shall not be required to be summed with the vapor capacity required in Section Pressure Relief Device Capacity Determination *Pressure relief devices shall have sufficient mass flow carrying capacity to limit the pressure rise in a protected equipment to prevent its catastrophic failure. The minimum required relief capacity shall depend on the equipment being protected and the scenarios under which overpressure is being created. The following scenarios shall be considered when determining the pressure relief device capacity for ammonia containing equipment. It is permissible to use manufacturer s data when determining relief requirements. All applicable scenarios shall be considered and the capacity of the pressure relief device shall be based on the scenario with the largest capacity requirements: Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 58

72 Overpressure due to External Fire i. Pressure Vessels: The required discharge capacity of a pressure relief device for each pressure vessel shall be determined by the following equation: C = ƒ D L (lbm/min) [C = ƒ D L [kg/s]] Where C = required discharge capacity of the relief device, lbm air/min [kg/s] ƒ = capacity factor of the relief device which is 0.5 [0.04] for ammonia [0.5 is in inch-pounds (IP), 0.04 is in International System of Units (SI)] D = L = outside diameter of vessel, ft [m] length of vessel, ft [m]. When one pressure relief device is used to protect more than one pressure vessel, the required capacity shall be the sum of the capacities required for each pressure vessel. ii. Oil Separators: The required discharge capacity for each oil separator shall be determined by the following equation: C r,os = ƒ D L (lbm/min) [C r,os = ƒ D L [kg/s]] Where C r,os = required discharge capacity of the relief device, lbm air/min [kg/s] ƒ = capacity factor of the relief device which is 0.5 [0.04] for ammonia D = L = outside diameter of the oil separator, ft (m) length of the oil separator, ft (m) Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 59

73 iii. Plate Heat Exchangers The capacity of the pressure relief device for plate heat exchangers shall be based on the largest projected area of the exchanger using the following equation: C r,plate HX = ƒ L 2 + W 2 H (lbm/min) [C r,plate HX = ƒ L 2 + W 2 H, [kg/s]] Where C r,plate HX = Minimum required relief device capacity for plate heat exchanger (lbm/min of air) [kg/s] ƒ = relief device capacity factor which is 0.5 [0.04] for ammonia L = length of the plate pack (ft) [m] W = width of the plate pack (ft) [m] H = Height of the plate pack (ft) [m] iv. Shell and Tube Heat Exchangers The capacity of the pressure relief device for shell and tube heat exchangers shall be based on the sum of the capacities required for the heat exchanger and the surge drum, if provided, as follows: C = ƒ (D v L v + D s L s ) (lb/min) [C = ƒ (D v L v + D s L s ) [kg/s]] Where C = required discharge capacity of the relief device, lb air/min [kg/s] ƒ = capacity factor of the relief device which is 0.5 [0.04] for ammonia Dv = outside diameter of the main vessel portion of the shell and tube heat exchanger, ft [m] L v = length of main vessel portion of the shell and tube heat exchanger, ft [m]. D s = L s = outside diameter of the surge drum, ft [m] length of the surge drum, ft [m]. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 60

74 v. Product Storage Tanks For product storage tanks with cooling jackets, the capacity of the pressure relief device shall be based on the diameter of the storage tank and the height of the cooling jacket as follows: C r,tank = ƒ D H (lbm/min) [C r,tank = ƒ D H [kg/s]] Where C r,tank = required discharge capacity of the relief device, lb air/min [kg/s] ƒ = capacity factor of the relief device which is 0.5 [0.04] for ammonia D = outside diameter of the tank, ft (m) H = height of the active portion of the heat exchanger (distance between ammonia supply and return) ft (m) *Potential for Overpressure due to Blocked Outlet i. Positive Displacement Compressor Protection. Pressure relief protection for positive displacement compressors shall comply with Section ii. Oil Cooling Heat Exchangers*The designer shall evaluate potential overpressure scenarios. iii. Hydrostatic overpressure relief Protection.*Hydrostatic overpressure relief shall comply with Section Potential for Overpressure due to Internal Heat Load.* The designer shall evaluate potential overpressure scenarios Other Potential Overpressure Scenarios. The designer shall evaluate other potential overpressure scenarios as applicable to the specific equipment being protected *Where combustible material is stored within 20 feet (6.1 m) of a pressure vessel, the relief device capacity factor, f, in the formulas shall be increased to f = 1.25 [f = 0.1] The rated discharge capacity of a pressure relief valve shall be determined in accordance with ASME B&PVC, Section VIII, Division 1 or international equivalent. The capacity marked on the nameplate shall be in lb/min air or in standard ft 3 /min (SCFM) of air at 60 F (SCFM x = lb/min of dry air). Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 61

75 The rated discharge capacity of a rupture member discharging under critical flow conditions shall be determined by the following equations: C = 0.64 P 1 d 2 (lb/min) d = 1.25 (C/P 1 ) 0.5 (in) [C = 1.1 x 10-6 P 1 d 2 (kg/s)] [d = 959 (C/P 1 ) 0.5 (mm)] Where C = rated discharge capacity in lb/min [kg/s] of air d = smallest of the internal diameter of the inlet pipe, retaining flanges or rupture member in inches [mm] P 1 = rated pressure (psig) x psi [P 1 = rated pressure [kpa gauge] x kpa] There shall be provisions to prevent plugging the piping in the event the rupture member relieves Pressure Relief Device Piping. Piping for relief of vapor shall comply with this section. Relief valve piping that discharges external to the refrigeration system is not part of the refrigeration system Stop valves shall not be installed in the inlet piping of pressure relief devices. Where installed in the outlet piping of pressure relief devices, the pressure drop effects of full area stop valves shall be taken into account in the engineering of the relief vent piping system. Where used, stop valves shall be locked open whenever any upstream relief device is in service The area of the opening through pipe; fittings; and pressure relief devices, if installed, including 3-way valves; between a pressure vessel connection as provided in Section and its pressure relief valve shall be not less than the area of the pressure relief valve inlet. This upstream system shall be such that the pressure drop will not reduce the relieving capacity below that which is required. Compressor vessel connections shall comply with Section Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 62

76 Discharge piping from pressure relief devices shall be steel pipe minimum schedule 40 for pipe sizes up to 6 and minimum schedule 20 for pipe sizes 8 and larger. The relief piping shall comply with the ferrous material requirements of ASME B31.5. EXCEPTIONS: 1. Relief piping shall be permitted to be galvanized or un-galvanized ASTM A53-Type F. When these grades of un-galvanized pipe are used, the pipe shall be clearly identified using paint striping or another method or shall be segrega3ted to prevent use in a refrigeration system. 2. Malleable iron ASTM A197 fittings shall be permitted for discharge relief piping The size of the discharge pipe from a pressure relief device shall not be less than the outlet size of the pressure relief device. The minimum size and total equivalent length of common discharge piping downstream from each of two or more relief devices shall be determined based on the sum of the discharge capacities of all relief devices that are expected to discharge simultaneously, with due allowance for the pressure drop in downstream sections Where piping in the system and other equipment required to comply with this section could contain liquid ammonia that can be isolated from the system during operation or service, Section 15.6 shall apply Discharge piping shall be supported in accordance with Section Relief piping shall be used only for relieving vapor from refrigerant relief valves. Relief piping shall not be used to relieve discharge from hydrostatic overpressure-relief devices or any other fluid discharges, such as secondary coolant or oil Discharge from Pressure Relief Devices *Atmospheric Discharge Pressure relief devices shall discharge vapor directly to the atmosphere outdoors in accordance with this section. EXCEPTION. In lieu of relieving directly to atmosphere, the following methods of discharging ammonia from pressure relief devices shall be permitted where approved by the AHJ: 1. Discharge through a treatment system. 2. Discharge through a flaring system in accordance with Section Discharge through a water diffusion system in accordance with Section Discharge using other approved means. The maximum length of the discharge piping installed on the outlet of pressure relief devices and fusible plugs discharging to the atmosphere shall be determined in accordance with this section. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 63

77 *The design back pressure due to flow in the discharge piping at the outlet of pressure relief devices and fusible plugs, discharging to atmosphere, shall be limited by the allowable equivalent length of piping determined by Equation (1) or (2). Equation (1): Allowable relief discharge piping length, English units L P d o ln.2146d P P P fc f 0 2 r 6 Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 64

78 Where Equation (2): Allowable relief discharge piping length, SI units L P d o ln d P P P fcr 500 f 7 2 L = equivalent length of discharge piping, ft [m]; C r = rated capacity as stamped on the relief device in lb/min [kg/s], or in SCFM multiplied by , or as calculated in ANSI/ASHRAE 15, Section for a rupture member or fusible plug, or as adjusted for reduced capacity due to piping as specified by the manufacturer of the device, or as adjusted for reduced capacity due to piping as estimated by an approved method; ƒ = Moody friction factor in fully turbulent flow (See Appendix A ); d = inside diameter of pipe or tube, in [mm]; ln = natural logarithm; P 2 = absolute pressure at outlet of discharge piping, psi [kpa]; P 0 = allowed back pressure (absolute) at the outlet of pressure relief device, psi [kpa]. For the allowed back pressure (P 0 ), use the percent of set pressure specified by the manufacturer, or when the allowed back pressure is not specified, use the following values, where P is the set pressure: a. for conventional relief valves, 15% of set pressure, P 0 = (0.15 P) + atmospheric pressure; b. for balanced relief valves, 25% of set pressure, P 0 = (0.25 P) + atmospheric pressure; c. for rupture members, fusible plugs, and pilot operated relief valves, 50% of set pressure, P 0 = (0.50 P) + atmospheric pressure. For fusible plugs, P is the saturated absolute pressure for the stamped temperature melting point of the fusible plug or the critical pressure of the ammonia, whichever is smaller, psi [kpa] and atmospheric pressure is at the elevation of the installation above sea level. A default value is the atmospheric pressure at sea level, 14.7 psi [ kpa]. The termination of pressure relief device discharge piping relieving to atmosphere shall be not less than 15 feet [4.6 m] above grade and not less than 20 feet [6.1 m] from windows, ventilation intakes, or exits. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 65

79 The discharge termination from pressure relief devices relieving to atmosphere shall not be less than 7.25 feet [2.2 m] above the roof. Where a higher adjacent roof level is within 20 feet [6.1 m] horizontal distance from the relief discharge, the discharge termination shall not be less than 7.25 feet [2.2 m] above the height of the higher adjacent roof. Discharge piping shall be permitted to terminate 7.25 feet [2.2 m] above platform surfaces, such as upper condenser catwalks, and roofs that are occupied only during service and inspection. The termination of the discharge shall be directed vertically upward and arranged to avoid spraying ammonia on persons in the vicinity. The termination point of the relief vent discharge shall have a provision to block foreign material or debris from entering the discharge piping. Discharge piping from pressure relief devices discharging to atmosphere shall have a provision for draining moisture from the piping Flaring Systems. Flaring systems, if installed, shall be tested to demonstrate compliance with the design Discharge Through a Water Diffusion Tank. Where pressure relief devices discharge to a water tank, the tank shall be sized for containing one gallon of water for each pound of ammonia (8.3 liters of water for each kilogram of ammonia) that would be released in one hour from the largest relief device connected to the discharge pipe. The water shall be prevented from freezing. The discharge pipe from the pressure-relief device shall distribute ammonia in the bottom of the tank but no lower than 33 feet (10 m) below the maximum liquid level. The tank shall be large enough to contain the volume of water and ammonia without overflowing Equipment and Piping Hydrostatic Overpressure Protection *Protection Required. Protection against overpressure due to thermal hydrostatic expansion of trapped liquid ammonia shall be provided for equipment and piping sections that can be isolated and can trap liquid ammonia in an isolated section in any of the following situations: 1. Automatically during normal operation. 2. Automatically during shut down by any means, including alarm or power failure. 3. During planned isolation for standby or seasonal conditions. 4. Due to an equipment or device fault. Exception: If trapping of liquid with subsequent thermal hydrostatic expansion is only possible during maintenance or service operations, engineering or administrative controls, or both, shall be permitted as the means of relieving or preventing overpressure. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 66

80 Protection Method. Where protection against overpressure due to thermal hydrostatic expansion of trapped liquid ammonia is required, one or both of the following mitigations methods shall be used: 1. Provide a static relief device or check valve relieving to another part of the closed-circuit system. 2. Provide an expansion compensation device Manual Isolation. Manual isolation of equipment and piping sections shall only be performed by personnel who are authorized to perform this service. Prior to and during the service, precautions shall be taken to protect against overpressure due to thermal hydrostatic expansion of trapped liquid ammonia. Where a Lockout/Tagout procedure is required for the energy control, the procedure and training shall be in compliance with 29 CFR Use of Static Pressure-relief Valves. As required by Section , static pressure-relief valves shall not be used as shut-off valves. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 67

81 Chapter 16. Instrumentation and Controls 16.1 General Scope. Instrumentation and controls shall comply with this chapter Operating Parameter Monitoring. Instruments and controls shall be provided to indicate operating parameters of the refrigeration system and equipment and provide the ability to manually or automatically control the starting, stopping and operation of the system or equipment. The instruments and controls shall provide notice if the system s critical operating parameters, as determined by the owner or operator have been exceeded Documentation. The function, sequence and operating design parameters of each provided control shall be obtained or documented by the owner or operator. The owner or operator shall maintain such documentation in a location that is accessible at the site *Monitoring an Ammonia Release During a Power Failure A means shall be provided for monitoring the concentration of an ammonia release in the event of a power failure *Restricted Access to Safety Settings. Changing of safety settings shall be limited to authorized personnel only. Changing of system operational settings shall not permit or affect changes to safety settings Electrical Control Systems. Electrical control systems shall comply with the Electrical Code Ultimate Strength. The pressure-containing envelope maximum allowable working pressure of instruments and visual liquid level indicators shall be equal to or greater than the design pressure of the system or subsystem in which they are installed Visual Liquid Level Indicators: Visual liquid level indicators, including but not limited to glass bull s eyes, flat armored glass linear sight glasses or sight columns and pressure gauges, shall comply with this section Design and Selection *Design of visual liquid level indicators shall be in accordance with one or more of the following: 1. Comply with the ultimate strength requirement in Section Use a performance-based pressure-containment design substantiated by either proof tests as described in ASME B&PVC, Section VIII, Division 1, Section UG-101 or international equivalent, or an experimental stress analysis. The design pressure shall not be less than the pressure required by Section 5.6. Sight glasses and linear liquid level indicators shall not be installed in areas with a risk of repeated thermal expansion or where there is a risk of liquid hammer. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 68

82 Damage Protection. Visual liquid level indicators used to observe ammonia level, such as in a vessel or heat exchanger, shall be designed and specified for installation in a manner that provides protection from physical damage *Linear Liquid Level Indicators. Linear liquid level indicators shall be fitted with internal check-type shutoff valves. Protection against accidental breakage of the glass tube from any direction shall be provided for the entire length of the tube. EXCEPTION: Liquid-level-indicators using bull's-eye type sight glasses Bull s Eye Sight Glasses. Bull s eye sight glasses shall be verified as compatible for use with ammonia, and the thickness, diameter and type of glass used shall be verified as appropriate for the intended application. Bull s eye sight glasses shall be provided with a traceable serial number or other form of identification that does not compromise the glass structure or integrity *Electric and Pneumatic Sensor Controls. Sensing devices that initiate control pulses or signals for refrigeration systems shall comply with this section Design. Sensing devices which initiate control pulses or signals shall have a design pressure that is not less than the design pressure required by Section 5.6. In addition, the sensing devices shall be in accordance with one or more of the following: 1. Comply with the ultimate strength requirement in Section Document a successful performance history for devices in comparable service conditions. 3. Use a performance-based pressure-containment design substantiated by either proof tests as described in ASME B&PVC, Section VIII, Division 1, Section UG-101 or international equivalent, or an experimental stress analysis Equipment Identification. Manufacturers producing electrical or pneumatic controls shall provide the following minimum nameplate data: 1. Manufacturer s name 2. Manufacturer s serial number, where applicable 3. Manufacturer s model number 4. Electric supply: volts, full load amps, frequency (Hz), phase, where applicable 5. Pneumatic system: control range: maximum supply air pressure, minimum supply air pressure, required ACFM, where applicable 6. Flow direction, where applicable 7. Any special characteristics of a control device shall be noted either on the name tag or in the accompanying literature Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 69

83 Chapter 17. Ammonia Detection and Alarms 17.1 Scope. Ammonia leak detection and alarms shall comply with this chapter Power for Detectors and Alarms. The power supply for the ammonia detectors and alarms shall be a dedicated branch circuit. In the event of a loss of power on other circuits or an emergency shutdown of refrigeration equipment, the ammonia detection and alarm system shall remain on. In the event of a loss of power to the ammonia detection and alarm system, a power failure trouble signal shall be sent to a monitored location Testing Schedule. A schedule for testing ammonia detectors and alarms shall be established based on manufacturers recommendations, unless modified based on documented experience Minimum Test Frequency. Where manufacturers recommendations are not provided, ammonia detectors and alarms shall be tested not less than once per year Detector Placement. A leak detection sensor, or the inlet of a sampling tube that draws air to a leak detection sensor, shall be mounted in a position where ammonia from a leak is expected to accumulate. In rooms equipped with continuous exhaust ventilation, the location of leak detection sensors and sampling tubes shall take into account the air movement towards the inlet of the ventilation system. Leak detection sensors and sampling tube inlets shall be positioned where they can be accessed for maintenance and testing *Alarms. The audible alarms providing notification shall provide a sound pressure level of 15 decibels (dba) above the average ambient sound level and 5 dba above the maximum sound level of the area in which it is installed Signage. Ammonia leak detection alarms shall be identified by signage adjacent to visual and audible alarm devices Detection and Alarm Levels. Where an ammonia detection and alarm level is specified by this standard, the operational criteria shall be as specified in this section. EXCEPTION: Where approved, alternatives to fixed ammonia leak detectors shall be permitted for areas with high humidity or other harsh environmental conditions that are incompatible with detection devices Level 1 Ammonia Detection and Alarm. Level 1 ammonia detection and alarm shall have the following features: 1. At least one ammonia detector shall be provided in the room or area. 2. The detector shall activate an alarm that reports to a monitored location so that corrective action can be taken at a level no higher than 25 ppm. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 70

84 Level 2 Ammonia Detection and Alarm. Level 2 ammonia detection and alarm shall have the following features: 1. At least one ammonia detector shall be provided in the room or area. 2. The detector shall activate an alarm that reports to a monitored location so that corrective action can be taken at a level no higher than 25 ppm. 3. Audible and visual alarms shall be provided inside the room to warn that, when the alarm has activated, access to the room is restricted to authorized personnel and emergency responders Level 3 Ammonia Detection and Alarm. Level 3 ammonia detection and alarm shall have the following features, and for machinery rooms shall comply with Section : 1. At least one ammonia detector shall be provided in the room or area. 2. The detector shall activate an alarm that reports to a monitored location so that corrective action can be taken at a level no higher than 25 ppm. 3. Audible and visual alarms shall be provided inside the room to warn that, when the alarm has activated, access to the room is restricted to authorized personnel and emergency responders. For machinery rooms, additional audible and visual alarms shall be located outside of each entrance to the machinery room. 4. Upon activation of the alarm, control valves feeding liquid and hot gas to equipment in the affected area shall be closed, and pumps, fans, or other motors associated with the ammonia refrigeration equipment in the room shall be de-energized. 5. Upon activation of the alarm, emergency exhaust systems, where required, shall be activated. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 71

85 Part 4 Appendices Appendix A. (Informative) Explanatory Material This informative appendix is not a part of the standard. It provides explanatory information related to provisions in the standard. Sections of the standard that have associated explanatory information in this appendix are marked with an asterisk * after the section number, and the associated appendix information is located in a corresponding section number preceded by A. A.1.2 A.2.2 It is the intent of this standard to NOT apply retroactively to existing buildings or facilities that contain ammonia refrigeration systems. This standard is only intended to apply to cases where ammonia refrigeration systems or equipment are newly installed, not including in-kind replacement or repair of existing equipment. Commercial Occupancy: Commercial occupancies include office, work and storage areas that do not qualify as industrial occupancies. Packaged Systems: Examples of packaged systems that constitute large portions of a refrigeration system include recirculator packages, condenser packages, compressor packages and chiller packages. Public Assembly Occupancy: Examples of public assembly occupancies include, but are not limited to, auditoriums, stadiums, arenas, ballrooms, classrooms, passenger depots, restaurants and theaters. A.4.2 A A See Chapter 2 for Occupancy Classifications. ASHRAE 15 and model mechanical codes include a longstanding allowance to install evaporators in industrial occupancies outside of a machinery room. However, these documents do not specifically indicate whether equipment that is ancillary to the heat exchanger portion of an evaporator, such as surge drums or liquid pumps, are or are not permitted to be considered as part of an evaporator for the purpose of applying this allowance. This edition of IIAR 2 included the evaporator exception for consistency with ASHRAE 15 and model mechanical codes without modification, and thereby, determination of equipment that might or might not be permitted to be considered as part of an evaporator remains a decision of the designer and the AHJ. In some cases, the type of equipment, such as a semi-hermetically sealed or hermitically sealed pump, versus an open-drive pump, will influence the determination. The value of 320 ppm used in IIAR 2 is based on the Immediately Dangerous to Life and Health (IDLH) value provided by ASHRAE 34 for ammonia, which is consistent with the value in the International Fire Code. Other sources, including NIOSH and the Uniform Mechanical Code specify a value of 300 ppm; however, in the scheme of ammonia refrigeration release incidents, the difference between these values is not considered to be consequential. Also note that other sections of IIAR 2 that establish regulations based on ½ of the IDLH value use a 160 ppm concentration, rather than 150 ppm, which might be used by other codes or standards that are based on a 300 ppm IDLH value. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 72

86 Provided that a system complies with the 320 ppm limit, it is permissible to have some equipment located outdoors and some inside since this section would permit the entire system to be inside, and placing some equipment outside further reduces occupant exposure risk. A A.5.4 A See Appendix B (Informative) for additional information regarding the characteristics and properties of ammonia. The provisions in this section are generally based on ASHRAE 15, however, they are different in that ASHRAE 15 includes refrigerants that are typically heavier-than-air. Ammonia is a lighter-than-air gas, and IIAR 2 provisions address this difference. For the purpose of determining how to treat interconnected spaces, as separate or singular, ASHRAE 15 recognizes permanent wall openings that might include doors, passages and conveyor openings. However, because ammonia is lighter than air and tends to rise, as compared to other refrigerants that tend to sink, the determination of openings that might create interconnected spaces for a facility containing ammonia must take into account ammonia s buoyancy. Accordingly, the elevation of the opening must be considered. In addition, any physical opening that is determined to create interconnected spaces must be able to reliably remain unobstructed through the life of the building. In addition, where the calculation procedure is being performed for the purpose of determining whether emergency ventilation is needed to reduce the risk of a flammable concentration, in accordance with Section , it is important to be very conservative in determining interconnected spaces. The threshold for requiring emergency ventilation is based on a calculated average concentration in the space of 40,000 ppm, which is 25- percent of the lower-flammable-limit, and this average concentration could be associated with higher concentrations in local areas. Given that ignition sources such as fueled heaters and ordinary light fixtures would be permitted at the ceiling level in these areas, it is important that the calculation provides a high level of confidence that an ignitable concentration will not exist in any location where ignition sources might be present. A A Using the smallest volume space for a release event provides a worst case scenario analysis. Where a damper might be expected to stop airflow between two rooms or spaces, those spaces should not be considered as connected for purposes of evaluating a worst case scenario of an ammonia release into the smallest exposed space. Fire dampers, smoke dampers and dampers that provide both functions are normally open and will only close in a fire event, not an ammonia release event, and it is not the intent of this section to require a design that assumes an ammonia release that is simultaneous with a fire. Adjustable dampers, such as those that might be found on a variable airflow system need not be considered as stopping the airflow between two rooms or spaces as long as the damper is not capable of closing more than 90-percent during normal operation. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 73

87 A.5.6 A A A A.5.9 A A A A A A It should be noted that ASHRAE 15 includes a requirement that the design pressure of refrigeration systems need exceed the critical pressure for a refrigerant unless higher pressure is anticipated during operating, standby or shipping conditions. In the case of ammonia, the critical pressure is 1636 psi, which far exceeds any system design pressure; therefore, this provision is not relevant in IIAR 2 and was not included. The intent of this requirement is to avoid nuisance shutdowns or nuisance releases caused by the lack of a buffer between normal operational pressure levels and pressure levels associated with abnormal or emergency conditions that lead to a shutdown or a release. For information on the appropriate allowances for design pressure, see the ASME B&PVC, Section VIII, Division 1, Appendix M. Examples of standby conditions that would be considered in applying this section include maintenance, shutdown and power failure. Air and water are examples of expected contaminants. Nevertheless, in trace amounts that might ordinarily be present in an ammonia refrigeration system, significant deterioration of materials, such as steel piping or vessels, is not expected. Section lists a variety of permissible methods for atmospheric release of noncondensable gases, including an allowance for other approved means that are not specifically stated. Such other means might include releasing gas through a water column. Insulation can also be provided for energy conservation purposes, as required by the owner or local energy conservation requirement. For additional information on insulation of piping, see the IIAR Piping Handbook. See Chapter 3 of the Uniform Mechanical Code and Chapter 3 of the International Mechanical Code, which provide requirements for access to all types of mechanical equipment, including ammonia refrigeration systems. In addition, Chapter 11 of the Uniform Mechanical Code includes special access provisions for ammonia refrigeration equipment. Examples of equipment that might require maintenance or functional control testing include liquid level indicators, float switches and high-pressure cut out switches. This section requires equipment to be designed and installed with serviceability in mind, including clearances for service tools and similar serviceability provisions. See OSHA 29 CFR for information on providing fixed stairs for access to serviceable equipment. Where multiple pieces of serviceable equipment are readily isolated by a single set of hand isolation valves, the use of a single set of valves meets the intent of this section. This requirement is consistent with ASHRAE 15, which regulates the secondary coolant. See ASHRAE 15, Section Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 74

88 A A replacement-in-kind change to equipment will not ordinarily require updating of emergency shutdown procedures. Examples of unique identification include valve tags and signs. A A A A A A A An example of an international standard is EN Parts 1-5 in accordance with national regulations satisfying the requirements of the European Pressure Equipment Directive (PED). Appendix D (Informative) provides further information on duplicate nameplates. Wind indicators are not required by IIAR 2. However, they are sometimes provided for use in conjunction with EPA or OSHA emergency planning and response procedures. See EPA Alert 550-F , August See IIAR Bulletin No. 114 for guidance on identification of ammonia piping and equipment. Examples of rotating parts that might require protection include shafts, belts, pulleys, flywheels and couplings. Used equipment includes equipment that is relocated or purchased after previous use. Further information on structural load requirements can be found in the Building Code and the Mechanical Code. Also see Section A For additional information, see OSHA 29 CFR A A A A A The Building Code provides comprehensive regulations for means of egress, but of particular concern in ammonia refrigeration facilities is the required minimum clear height and width for access to equipment in areas that contain piping or machinery. The designer is cautioned to ensure that the minimum clear height and width provisions in the building code for aisles are maintained in the design. See 2015 International Building Code Section , Exception and Sections and See Section and for requirements related to doors and Section for pipe penetrations. Also see the definitions of tight construction and tight fitting door in Chapter 2. See 29 CFR for information regarding ladder access. The allowance to permit a machinery room without direct egress to the outside is consistent with provisions in model building codes that permit Group H-2 occupancies to be located without an exterior wall when the room does not exceed 500 square feet in area. Visual alarms can be provided by strobes or other distinctive visual signaling devices. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 75

89 A The threshold for initiating emergency ventilation has been changed in the 2014 edition of IIAR 2. Some previous editions and model mechanical codes specify that emergency ventilation is to be activated at an ammonia concentration not exceeding 1,000 ppm. The 1,000 ppm value had been based on concerns that serious damage to equipment might occur if a large volume of frigid outdoor air unnecessarily flooded a machinery room in a cold climate zone because a leak detector sensed a small leak or a small maintenancerelated release. While this remains a valid concern, the concern is overshadowed by two more important considerations. First, IIAR 2 no longer requires normal mechanical ventilation to initiate at TLV/TWA concentrations (25 ppm), as it did in some previous editions. Activation of emergency ventilation at ½ of the IDLH concentration (160 ppm), rather than 1,000 ppm, retains a means to quickly ventilate a significant release. Concentrations that might precede activation of emergency ventilation, those in the range between TLV/TWA (25 ppm) and ½ IDLH (160 ppm), are not acutely hazardous to occupants, and the strong smell of ammonia associated with such concentrations will be readily noticed by occupants as a cue to self-evacuate Second, it is recognized that emergency response by plant personnel is significantly less complex for releases not exceeding ½ IDLH (160 ppm) concentrations, versus concentrations of 1,000 ppm or more. Activating emergency ventilation at the lower threshold increases the likelihood of emergency responders encountering reduced ammonia concentrations when they arrive at the scene, thereby limiting responders exposure risk and increasing the likelihood of an incident being controlled in the early stages. To address the cold climate concern discussed above, consideration can be given to developing alternative solutions for activating the ventilation system or conditioning supply air before it is introduced into the machinery room, as would be necessary for activating at the TLV/TWA (25 ppm). A A This requirement correlates with the minimum breathing air requirements in model mechanical codes for machinery rooms but has been expanded to permit the use of natural ventilation where natural ventilation can be demonstrated as meeting the minimum air exchange requirements. When selecting a location for exhaust discharge to the atmosphere it is preferable to select a location that will minimize the risk of creating a nuisance or hazard in the event of an ammonia release. Consideration should be given to the natural airflow around the building, prevailing winds and surrounding structures. A Fans in a machinery room are not required to be suitable for installation in Class I, Division 2 atmospheres because the Electrical Code does not require hazardous location electrical equipment in areas containing ammonia that are provided with adequate mechanical ventilation. Nevertheless, in an abundance of caution, this Standard requires an extra level of protection for fan motors in machinery rooms. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 76

90 A A A See ASHRAE Handbook, Fundamentals, Chapter 14, Climate Design Information for determination of dry bulb temperature. Appendix K (Informative) provides an example calculation for determining an emergency ventilation rate. It is sometimes considered convenient to schedule testing of emergency ventilation systems in conjunction with testing and calibration of ammonia detection equipment. A reduced frequency for testing might be established after enough test data has been accumulated to support the reliability of the ventilation equipment with less frequent testing. A A A A International Mechanical Code (IMC) Table establishes the degree of severity designations to be provided on the NFPA 704 placard, which differs for indoor and outdoor locations based on the risk of ignition. The IMC designates health, fire and reactivity to be for indoor locations and for outdoor locations. See also Appendix J for further information regarding machinery room signs. Model mechanical codes and ASHRAE 15 require refrigerant leak detection to be provided where certain refrigeration equipment is located outside of a machinery room. Nevertheless, because ammonia is self-alarming, with a pungent odor that warns of ammonia s presence well before the concentration becomes acutely hazardous, leaks are readily detected when someone is in the area. For areas that operate on a 24/7 work schedule that have an emergency plan in place for dealing with an ammonia release, fixed detection systems are sometimes omitted in favor of relying on occupants to detect and respond to a leak in accordance with the emergency plan. In jurisdictions where a model mechanical code has been adopted, use of an alternative to fixed detection will require approval of the AHJ, as provided in Section because the mechanical codes specifically require leak detection for these applications. In jurisdictions where a mechanical code has not been adopted, the determination of the approach to detection will be determined by the designer as provided in Section based on an assessment of the area to be protected. By referencing Section Item 4, it is specifically intended that this section, and the associated provisions for ventilation, not apply for equipment that is permitted outside of a machinery room by Section Items 1-3. If an area includes multiple refrigeration systems, each system is permitted to be considered individually when calculating release concentration. In some cases, an enclosure might be provided for equipment containing ammonia, and local ventilation within the enclosure might be used to meet the emergency ventilation provisions in lieu of ventilating the entire room or area. See Appendix K. Alternatives to ventilation might include systems that employ a water mist system or a CO₂ fogging system, where approved by the AHJ. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 77

91 A A A A A.10.1 A A.13.1 A A A A.13.3 A A A Appendix E (Informative) describes an acceptable method of calculating the discharge capacity of positive-displacement compressor pressure-relief devices. The referenced safety controls are commonly referred to as a low pressure cutout and a high pressure cutout. An indicating-type lubrication failure control is commonly referred to as a low oil pressure cutout. Compressor designs differ. Sometimes installing a discharge check valve is sufficient to avoid liquid accumulation and backflow. For example, some designs that use high pressure ammonia for oil cooling will also require a suction check valve. Other means, such as automatic shut-off valves, are not often used but can be effective in lieu of check valves. The requirements in this section are intended to protect compressors from liquid slugging. The location of a condenser relative to the receiver should be arranged to provide sufficient refrigerant head for the ammonia to properly drain. See Appendix H (Informative). Piping is defined as including both pipe and tubing. The requirement to comply with ASME B31.5 applies to both shop fabricated and field erected piping. In addition to materials that are specifically mentioned therein, ASME B31.5 Section also allows the use of other materials, which can be accepted as compliant with IIAR 2 where approved by the AJH based on the submittal of documentation that demonstrates the suitability of the pipe for the intended application. See Appendix L (informative) for criteria historically applied to ammonia piping in closed-circuit ammonia refrigeration systems. Tubing is used for compressor lubrication lines; small bore pressure sensing lines; hydrostatic relief lines; etc. Refer to IIAR 3 for the manufacturing, design and performance requirements of ammonia refrigeration valves and strainers. The exception provides for cases where a designer chooses to install a directional valve in a backwards orientation, which is a method that is sometimes used to provide a high level of resistance to backflow. This valve arrangement has the potential to trap liquid. Shut-off valves are also referred to as stop valves. Control valves and other valves without a manually operable and lockable actuating element intended to stop flow for isolation purposes, such as solenoid valves and check valves, are not classified as shut-off or stop valves. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 78

92 A.13.4 A.13.5 A A A A.15.1 A.15.2 A A A A ASME B31.5 provides guidance for certain pipe support and hanger components, protective coatings, etc. See also Appendix F (Informative) for additional information. See Section A for additional information related to clearances required by the Building Code. Examples of loads include ammonia weight, insulation, frost, ice, seismic, wind, and thermal. It is the intent of this section to include all packaged systems, regardless of whether the enclosure is applied at point of fabrication, during installation or after installation. The intent of requiring emergency valves to be directly operable is to have the valve available for rapid operation in the event of an emergency. Accordingly, a valve operating wheel needs to be permanently installed on manual emergency valves that are not chain operated, and access to operate valves cannot require use of a ladder, stool or similar assistive device. See Appendix I (Informative) for additional information related to overpressure protection. Overpressure protection should be install as close as possible to or directly on the pressure vessel or other equipment being protected to minimize pressure drop that may occur in the piping feeding the inlet side of the valve. The connection for pressure relief protection should be positioned at the highest practical point on a pressure vessel or other equipment being protected. See ASME B&PVC, Section VIII, Division 1, Section UG-127. Note that SCFM x = lb/min of dry air. Appendix C (Informative) provides a method to determine the capacity for safety relief valves to relieve overpressure due to blocked outlets on oil cooling heat exchangers. Appendix G (Informative) provides a method for determining the size of hydrostatic overpressure-relief valves. Appendix C (Informative) provides a method for determining the capacity for safety relief valves to relieve pressure due to internal heat loads in heat exchangers A It should be noted that IIAR 2 requires application of the increased relief capacity factor for materials that are stored within 20 feet of a pressure vessel; whereas, ASHRAE 15 requires application of the increased relief capacity factor for materials that are used within 20 feet of a pressure vessel. The technical concern relates to increased exposure of the pressure vessel to an external fire, and IIAR 2 takes the position that storage of combustible materials adjacent to a pressure vessel constitutes the more accurate description of a scenario warranting application of the additional safety factor. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 79

93 A A A A A A A.16.3 For cases where a water diffusion tank is being contemplated, consideration should be given to using an atmospheric relief discharge, but increasing the termination point to not less than 30 feet (9.1 m) above the adjacent grade, or roof level. Research indicates that a high velocity vertical discharge at such elevations is very effective at diffusing ammonia into air and minimizing the risk of ammonia exposure at ground level. An example of a possible cause of hydrostatic overpressure related to seasonal conditions is the closing valves in ammonia lines to and from evaporative condensers during cold weather conditions. One possible means of monitoring ammonia concentration resulting from a leak during a power failure is a portable ammonia monitoring device. Examples of systems that might be inadvertently impacted by unauthorized personnel include emergency exhaust and equipment shutdown controls. For these systems and others, an unauthorized individual might mistakenly change the set points for normal system operation related to temperature, pressure, flow or vessel levels, but unintentionally affect alarm or emergency control settings. The basis of a performance-based design could be an analysis that is consistent with the general design philosophy embodied in ASME B31.5. Linear liquid level indicators are sometimes referred to as sight columns. It is recommended that linear liquid level indicators be of the flat armored glass type in preference to the tubular glass type. Relay switches, contactors, and starters are not addressed by this section. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 80

94 A Typical Moody friction factors (ƒ) for fully turbulent flow are provided in Tables A (1) and A (2). Table A (1) Typical Moody Friction Factors, Steel Tubing Table A (2) Typical Moody Friction Factors, Steel Piping Tubing OD (in.) DN ID (in.) ƒ Piping NPS DN ID (in.) ƒ A.17.5 The minimum audibility required for fire alarm signaling devices is normally a sound pressure level of 15 decibels (dba) above the average ambient sound level and 5 dba above the maximum sound level in the area where the device is installed. This was determined to be a suitable level for ammonia detection alarms to ensure adequate audibility. The intent of including a specific sound pressure level in dba is to provide a measurable basis for alarm design and to determine adequacy of the audibility where someone might question if an alarm is reasonably loud when the alarm is commissioned. A difference of opinion in this regard could be resolved by using a sound meter. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 81

95 Appendix B. (Informative) Ammonia Characteristics and Properties This appendix is not part of this standard. It is merely informative and does not contain requirements necessary for conformance to the standard. It has not been processed according to the ANSI requirements for a standard and may contain material that has not been subject to public review or a consensus process. B.1 Ammonia Characteristics The term ammonia, as used in this standard, refers to the compound formed by combination of nitrogen and hydrogen, having the chemical formula NH3. It is not to be confused with aqua ammonia, which is a solution of ammonia gas in water. Whenever the term ammonia appears in this standard, it means refrigerant-grade anhydrous ammonia. Experience has shown that ammonia is difficult to ignite and, under normal conditions, is a very stable compound. It requires temperatures of F [ C] [ K] to cause it to dissociate slightly at atmospheric pressure. The flammable limits at atmospheric pressure are 15.5% to 27% by volume of ammonia in air. An ammonia-air mixture in an iron flask does not ignite below 1204 F [651.1 C] [925.3K]. Since ammonia is self-alarming, it serves as its own warning agent so that a person is not likely to voluntarily remain in concentrations which are hazardous. B.2 Physical Properties of Ammonia English Common Metric SI Molecular symbol NH3 NH3 NH3 Molecular weight lb/lbmol g/mol g/mol Boiling point at one atmosphere* F C K Freezing point at one atmosphere* F C 195.5K Critical temperature F C K Critical pressure 1644 psig kg/cm 2 (gauge) MPa (gauge) Latent heat at -28 F (-33 C)(240.15K) and one atmosphere Btu/lb cal/g MJ/kg Relative density of vapor compared to dry air at 32 F (0 C)(273.15K) and one atmosphere Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 82

96 Vapor density at -28 F (-33 C)(240.15K) and one atmosphere lb/ft kg/m kg/m 3 Specific gravity of liquid at -28 F (-33 C)(240.15K) compared to water at 39.4 F (4.0 C) (277.1K) Liquid density at -28 F (-33 C)(240.15K) and one atmosphere* Specific volume of vapor at 32 F (0 C)(273.15K) and one atmosphere* lb/ft kg/m kg/m ft 3 /lb m 3 /kg m 3 /kg Flammable limits by volume in air at atmospheric pressure 15.5% to 27% 15.5% to 27% 15.5% to 27% Ignition temperature 1204 F C K Specific heat, gas at 59 F (15 C)(288.15K) and one atmosphere* At constant pressure (cp ) At constant volume (cv ) Btu/lb F Btu/lb F cal/g C cal/g C kj/kg K kj/kg K Ratio of specific heats k(cp/cv, also ) at 50 F (15 C)(288.15K) and one atmosphere* NOTE: *One standard atmosphere = psia [ kg/cm 2 absolute] [ kpa absolute] Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 83

97 Appendix C. (Informative) Methods for Calculating Relief Valve Capacity for Heat Exchanger Internal Loads INTRODUCTION This informative appendix presents approaches for determining the capacity of relief valves for overpressure scenarios not explicitly covered in Chapter 15. This information can be used to document a basis for relief device capacity determination for heat exchangers that may be subject to overpressure due to internal heat loads or blocked valves that can lead to high refrigerant pressures. Pressure relief devices need to have sufficient mass flow carrying capability (capacity) to limit the pressure rise in protected equipment to prevent its catastrophic failure. The minimum required relief device capacity will depend on the specific equipment being protected and the scenarios under which overpressure is being created. The maximum relief device capacity is not limited by codes and standards. However, over-sizing relief valves shall be avoided to prevent unstable relief device operation. Although the methods presented in this informative appendix are intended to apply across a wide range of refrigeration equipment and operating conditions, it is not possible to neatly prescribe relief device sizing and selection criteria to cover all situations. The approach presented here is intended to be illustrative of the process that can be followed in establishing pressure relief requirements for specific situations. As such, the use of sound engineering principles and the application of engineering judgment are expected. It is important to emphasize that for all of the cases considered, the rate of refrigerant vapor production needs to be converted to an air mass flow since all of the relief devices are rated on an air basis. In the sections that follow are methods for relief capacity determination for different types of heat exchangers based on internal heat addition. NOMENCLATURE c p,fluid - secondary fluid heat capacity (Btu/lb m- F) cp fluid,cip- clean-in-place fluid heat capacity (Btu/lb m-ºf) C r - minimum required discharge capacity of the relief device for a vessel (lb m/min of air) C r,plate HX - minimum required relief device capacity for plate heat exchanger (lb m/min of air) C r,os - minimum required discharge capacity of the relief device protecting an oil separator (lb m/min of air) C r,tank - minimum required discharge capacity of the relief device protecting a product tank heat exchanger (lb m/min of air) D - outside diameter of vessel or product tank (ft) D s - outside diameter of surge drum (ft) D v - outside diameter of the main vessel portion of the shell-and-tube heat exchanger (ft) f - relief device capacity factor that depends on refrigerant type and whether combustible materials are in close proximity to the pressure vessel (see ASHRAE for capacity factor values) H - height of the plate pack or tank heat exchanger (ft) h vapor,sat - saturated vapor refrigerant enthalpy at the fully accumulated relief device set pressure (Btu/lb m) h liquid,sat - saturated liquid refrigerant enthalpy at fully accumulated relief device set pressure (Btu/lb m) L - length of the vessel or plate pack (ft) Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 84

98 LMTD - Log mean temperature difference ( F) L s - length of surge drum (ft) L v - length of the main vessel portion of the shell-and-tube heat exchanger (ft) m brine - secondary fluid mass flow rate (lb m/min) m fluid, CIP - clean-in-place fluid mass flow rate (lb m/min) m refrigerant - refrigerant vapor generation rate (lb m/min) m refrigerant, OC - mass flow rate of refrigerant vapor generated by the oil cooler (lb m/min) mrefrigerant, tank - mass flow rate of refrigerant vapor generated in a tank heat exchanger (lb m/min) Pr - Prandtl number for fluid used to establish the nominal UA (-) Pr' - Prandtl number for fluid used to establish the modified UA' (-) Q - heat exchanger heat flux (Btu/min) Q OC - oil cooling heat exchanger heat load (Btu/min) T fluid,cip,supply - maximum fluid supply temperature during CIP (ºF) T refrigerant - refrigerant saturation temperature ( F) T ref,sat - refrigerant s saturation temperature at the relief valve set pressure (ºF) T return - load-side heat exchanger secondary fluid return temperature ( F) T supply - load-side heat exchanger secondary fluid supply temperature ( F) UA - overall heat transfer coefficient-area product (Btu/min- F) UA' - modified overall heat transfer coefficient-area product (Btu/min- F) W - width of the plate pack (ft) - refrigerant-to-product tank effectiveness (estimated as 0.2 for bulk tanks) APPLICATION If a heat exchanger is built to the requirements of the ASME B&PVC, Section VIII, Division 1 and is physically stamped as such, it requires pressure relief protection per ASME B&PVC Section VIII, Division 1, Section UG-125. In cases where conventional pressure relief protection is not required, it is often desirable to size a suitable process relief that will prevent over-pressurizing the heat exchanger during abnormal operation. The first step in determining the minimum required mass flow for relief protection is defining the scenarios likely to cause the overpressure situation. Heat exchangers are susceptible to over-pressure by internal heat loads from either product or other secondary fluid flow streams (e.g. clean-in-place systems). In either situation, the key consideration for relief device sizing is determining the rate of refrigerant vapor production by evaporation which will be dependent on the heat load and the refrigerant properties (saturation pressure-temperature relationship and heat of vaporization). Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 85

99 Shell-and-Tube, Plate and Frame, and Scraped (Swept) Surface Heat Exchangers Most scenarios involve alternate means of thermal energy input to the heat exchanger when the refrigerant side of the chiller has been isolated from the refrigeration system but the secondary fluid side remains active. Examples of thermal loads that could generate excessive pressure in a shell-and-tube or plate-and-frame heat exchanger may include but are not limited to product loads and clean-in-place (CIP) loads. Of primary concern are those thermal energy sources whose temperatures that exceed the saturation temperature corresponding to the heat exchanger s maximum allowable working pressure (MAWP) or pressure relief device set pressure. If the maximum fluid-side supply temperature is less than the saturation temperature corresponding to the heat exchanger s MAWP, the pressure relief capacity can be determined by IIAR 2, Section If the maximum fluid-side temperature is greater than the saturation temperature corresponding to the heat exchanger s MAWP, vapor generation rates based on the internal loads shall be estimated to determine if a larger relief device capacity requirement results. The first step in the process of considering an internal heat load scenario that could generate an overpressure situation is to evaluate the normal capacity of the heat exchanger. The next step is to estimate the heat exchanger s capacity under the adverse load condition and determine the corresponding rate of refrigerant vapor generation. Lastly, the predicted rate of refrigerant vapor generation is converted to an equivalent air mass flow rate to allow relief device selection. Determining the rate of refrigerant vapor production can be accomplished by solving a system of equations that characterize the equipment heat transfer performance, as given by Equation (1), and the balance of both refrigerant-side and fluid-side energy flows as given by Equations (2) and (3), respectively. The system of governing equations is as follows: Where: Q UA LMTD (1) T LMTD T ln T return return supply T T T supply refrigerant refrigerant fluid p, fluid return supply Q m c T T (3) refrigerant vapor, sat liquid, sat Q m h h (4) Q = heat exchanger heat flux (Btu/min) UA = overall heat transfer coefficient-area product (Btu/min- F) LMTD = Log mean temperature difference ( F) T return = load-side heat exchanger secondary fluid return temperature ( F) T supply = load-side heat exchanger secondary fluid supply temperature ( F) (2) Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 86

100 T refrigerant = refrigerant saturation temperature ( F) m brine = secondary fluid mass flow rate (lb m/min) c p,fluid = secondary fluid heat capacity (Btu/lb m- F) m refrigerant = refrigerant vapor generation rate (lb m/min) h vapor,sat = saturated vapor refrigerant enthalpy at the fully accumulated relief device set pressure (Btu/lb m) h liquid,sat = saturated liquid refrigerant enthalpy at fully accumulated relief device set pressure (Btu/lb m) In a liquid-containing heat exchanger, the refrigerant temperature (T refrigerant) is assumed to be the saturation temperature corresponding to the pressure relief device set (opening) pressure. The enthalpy of vaporization (h vapor,sat h liquid,sat) for the refrigerant-side energy balance is evaluated at the pressure relief device set pressure as well. The return fluid temperature to the heat exchanger (T return) is estimated based on the load which is a function of the fluid flow rate and return fluid from process, CIP set temperature, etc. The mass flow rate of fluid on the load-side of the heat exchanger ( m fluid ) is required as well as the load-side fluid heat capacity (c p, fluid). The nominal value of the heat exchanger s overall heat transfer-area product (UA) is based on design operating conditions. Equation (1) is used to estimate a nominal or design UA. Once a nominal or design UA is established, it can be adjusted or corrected for use in estimating the refrigerant vapor production rate arising in an overpressure situation. For example, if the fluid-side flow rate would be expected to vary from the design condition, the following relationship based on the Dittus-Boelter turbulent heat transfer correlation could be used to predict a modified UA based on an alternative fluid-side flow rate. 0.8 m fluid Pr UA UA m fluid Pr Where: 0.4 (5) UA = nominal overall heat transfer coefficient-area product (Btu/min- F) UA = modified overall heat transfer coefficient-area product (Btu/min- F) Pr = Prandtl number for fluid used to establish the nominal UA (-) Pr = Prandtl number for fluid used to establish the modified UA (-) In addition, Equation (5) accommodates changes in working fluids when transitioning from a design load condition to a different working fluid that may arise and create an overpressure situation (e.g. changing from a fluid beverage during load conditions to a CIP solution during clean-up) that forms the basis for sizing pressure relief protection for the heat exchanger. The above-mentioned known information (T refrigerant, h vapor,sat, h liquid,sat, T return, m fluid simultaneously solve Equations (1), (3), and (4) to find the remaining three unknown variables:, c p,fluid, and UA) can be used to m refrigerant, T supply, and Q. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 87

101 The quantity of interest is the refrigerant vapor flow rate, m refrigerant, which represents the mass flow of vapor generated during the overpressure scenario. Once obtained, the resulting refrigerant mass flow rate must then be converted to an equivalent mass flow rate for air using the following relationship (ASHRAE Appendix F): C r C air refrigerant air mrefrigerant Crefrigerant Tair M refrigerant T M (6) Appendix C of ASHRAE 15 (2013) assumes a refrigerant temperature of 510 R [283 K] and an air temperature of 520 R [289 K]. Appendix C lists values of the constants, C air and C refrigerant, for a number of different refrigerants. The calculated air mass flow based on the estimated refrigerant vapor mass flow represents the minimum required relief capacity for the internal load scenario. Example: Scraped (Swept) Surface Heat Exchanger Heat Exchanger Characteristics for one manufacturer s scraped (swept) surface heat exchanger: U 300 Btu/hr ft 2 6 ft 2 A 14.5 ft psig MAWP 250 psig Heat Load Assumption Q Internal Load is created by 160 F CIP fluid UA LMTD U A (T CIP - T sat,ref ) Q m h h refrigerant vapor, sat liquid, sat m ref U A h vapor T h CIP liquid Tsat, ref min 60 hr Heat Exchanger Characteristics U = 300 Btu/hr-ft 2 - F A = 14.5 ft 2 MAWP = 150 psig [ h = 488 Btu/lb m, T sat,ref = 89.6 F] T CIP = 160 F Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 88

102 Btu ft hr ft F m ref Btu min lbm hr lbm 10.5 ( ammonia) min F m air lbm min air Heat Exchanger characteristics U = 300 Btu/hr-ft 2 - F A = 14.5 ft 2 MAWP = 250 psig [ h = 453 Btu/lb m, T sat,ref = F] T CIP = 160 F Btu ft hr ft F m ref Btu min lbm hr lbm 6.3 ( ammonia) min F m air lbm min air Oil Cooling Heat Exchangers Over-pressurization can occur when a thermosiphon oil-cooled screw compressor package is started while the refrigerant-side of the oil cooler is isolated (valved-out). In this case, the compressor will operate and reject heat to the oil cooler resulting in an increasing supply oil temperature back to the compressor over time. As the compressor continues to operate and reject a portion of its heat of compression through its oil to the oil cooling heat exchanger, a point will be reached when the on-board compressor safeties shutdown the unit on high oil temperature. A typical screw compressor package high oil temperature cut-out is approximately 205 F [96 C]. The saturation pressure corresponding to a refrigerant temperature equal to the oil at its high temperature cut-out of 205 F [96 C] is 825 psig for ammonia. Since this pressure is significantly greater than the oil cooling heat exchanger s maximum allowable working pressure, the oil cooler will be subject to overpressure under this scenario. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 89

103 The mass flow rate of refrigerant vapor generated on the refrigerant-side of an oil cooler in an overpressure situation is given by: m refrigerant, OC h Q oc h vapor, sat liquid, sat (7) Where: Q OC = oil cooling heat load generated by the compressor operating at design suction pressure and discharge pressures with a corresponding supply oil temperature at the compressor high temperature cut-out limit (Btu/min) m refrigerant, OC = mass flow rate of refrigerant vapor generated by the oil cooler (lb m/min) h vapor,sat = saturated vapor refrigerant enthalpy at the fully accumulated relief device opening pressure (Btu/lb m) h liquid,sat = saturated liquid refrigerant enthalpy at the fully accumulated relief device opening pressure (Btu/lb m) The best source for determining the overpressure condition oil cooling loads, Q OC, is by information provided from the compressor manufacturers. Some compressor manufacturers computerized selection programs provide this information based on users inputting the design suction and discharge pressures along with oil supply temperatures. The programs return the resulting oil cooling load under the modified (high oil supply temperature) conditions. The oil cooling load imposed on the oil coolers can be evaluated at these modified conditions or alternatively, the full oil cooling load can be taken for sizing the relief device. The resulting oil cooling load at the elevated operating condition (Q oc) can then be used to estimate the refrigerant mass flow rate using Equation (7). The refrigerant mass flow rate is then converted to an air basis using Equation (9); thereby permitting the selection of a relief device. Product Storage Tanks The scenario for refrigerant vapor generation in the heat exchanger due to internal loads arises during clean-in-place. The rate of refrigerant vapor generation during clean-in-place can be estimated as follows: m refrigerant, tank m cp T T h h fluid, CIP fluid, CIP fluid, CIP, supply ref, sat vapor, sat liquid, sat (8) Where: m refrigerant, tank = mass flow rate of refrigerant vapor generated in the heat exchanger (lb m/min) = refrigerant to product tank effectiveness (estimated as 0.2) m = CIP fluid mass flow rate (lb m/min) fluid, CIP cp fluid,cip T fluid,cip,supply = CIP fluid heat capacity (approximated as 1 Btu/lb m-ºf) = maximum fluid supply temperature during CIP (ºF) Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 90

104 T ref,sat = refrigerant s saturation temperature at the relief valve set pressure (ºF) h vapor,sat = saturated vapor refrigerant enthalpy at fully accumulated relief device set pressure (Btu/lb m) h liquid,sat = saturated liquid refrigerant enthalpy at fully accumulated relief device set pressure (Btu/lb m) After determining the refrigerant mass flow rate, the relief device capacity (on an air-equivalent basis) is found by using Equation (6). The greater of these two capacities forms the basis for relief device selection for a product tank. References ASHRAE Transactions, Pressure Relief Device Capacity Determination Reindl, Douglas T. and Jekel, Todd B., Industrial Refrigeration Consortium. University of Wisconsin-Madison, Madison, WI and American Society of Heating, Refrigerating, and Air conditioning Engineers, Atlanta, GA, (2009). ASHRAE Standard 15, Safety Standard for Refrigerating Systems, American Society of Heating, Refrigerating, and Air conditioning Engineers, Atlanta, GA, (2013). Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 91

105 Appendix D. (Informative) Duplicate Nameplates on Pressure Vessels This appendix is not part of this standard. It is merely informative and does not contain requirements necessary for conformance to the standard. It has not been processed according to the ANSI requirements for a standard and may contain material that has not been subject to public review or a consensus process. Duplicate Nameplates on Pressure Vessels The ASME B&PVC, Section VIII, Division 1 permits duplicate (or secondary) nameplates on pressure vessels. Duplicate nameplates may be desirable in certain circumstances, especially where the original nameplate may be obscured by insulation. Experience has shown that attempting to access the original nameplate for inspection through windows, removable insulation sections, stanchion mounting, etc. tends to compromise the integrity of the insulation system. Moisture ingress into the insulation system follows, with possible damage to the pressure vessel. The use of duplicate nameplates helps prevent vessel damage from inspection ports and other deliberate damage to insulation. Unfortunately, using duplicate nameplates creates the possibility that the wrong (duplicate) nameplate will be applied to a vessel. The ASME B&PVC, Section VIII, Division 1 specifies that the vessel manufacturer must ensure that the duplicate nameplate is properly applied. While the easiest way to accomplish this is for the manufacturer to weld the nameplate to a support or other permanent vessel appurtenance that will not be insulated, field installation is also permitted. (Some inspection authorities consider the insulation jacket as a permanent attachment to the vessel, and therefore the duplicate nameplate may be applied to the jacket.) The manufacturer s procedures for ensuring a proper match of duplicate to original must be rigorously followed. It is advisable to record the location of the original nameplate should inspection be necessary. Various inspection authorities such as State vessel inspectors may demand to inspect and/or approve the duplicate and original nameplates before insulation is applied. While many inspection bodies will accept a duplicate nameplate as evidence of ASME B&PVC, Section VIII, Division 1 compliance for an insulated vessel, authorized inspectors may always demand to inspect the original vessel, including its nameplate. In particular, when the inspector is concerned about the physical condition of the vessel or questions the provenance of the duplicate nameplate, he or she may require the entire insulation system or any part to be removed to permit inspection. Damage to the insulation system must be promptly and professionally repaired, and due allowance should be made for the shorter service life of the repaired insulation system. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 92

106 Appendix E. (Informative) Method for Calculating Discharge Capacity of a Positive Displacement Compressor Pressure Relief Device This appendix is not part of this standard. It is merely informative and does not contain requirements necessary for conformance to the standard. It has have not been processed according to the ANSI requirements for a standard and may contain material that has not been subject to public review or a consensus process. Reprinted by permission of The American Society of Heating, Refrigerating and Air-conditioning Engineers (ASHRAE). The following calculation method provides the required discharge capacity of the compressor pressure relief device in Section W r Where Q PL v v g Wr = mass flow of refrigerant, lbm/min [kg/s] Q = swept volume flow rate of compressor, ft 3 /min [m 3 /s] PL = fraction of compressor capacity at minimum regulated flow v = volumetric efficiency (assume 0.9 actual volumetric efficiency at relieving pressure is known) vg = specific volume of refrigerant vapor (rated at 50 F [10 C] saturated suction temperature), ft 3 /lbm [m 3 /kg] Next, find the relieving capacity in mass flow of air, Wa, for an ASME B&PVC-rated pressure relief device: W W r (E.2) Where a r w c rw c a r T T r a M M rw = refrigerant-to-standard-air-mass-flow conversion factor Mr = molar mass of refrigerant (17.0 for ammonia) Ma = molar mass of air = Ta = absolute temperature of the air = 520 R (289 K) ca = constant for air = 356 cr = constant for refrigerant (as determined from Equation E.4) Tr = absolute temperature of refrigerant = 510 R (283 K) a r (E.3) k 1 k 1 2 cr 520 k (E.4) k 1 Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 93

107 Where k = ratio of specific heats cp/cv cp = constant-pressure specific heat of refrigerant at a refrigerant quality of 1 at 50 F (10 C). cv = constant-volume specific heat of refrigerant at a refrigerant quality of 1 at 50 F (10 C). Constants for ammonia are listed below: k = Mr = 17.0 cr = rw = 1.28 EXAMPLE: Determine the flow capacity of a relief device for an ammonia screw compressor with a swept volume, Q, of 1665 ft 3 /min ( m 3 /s). The compressor is equipped with capacity control that is actuated at 90% of the pressure relief device set pressure to its minimum regulated flow of 10%. Q=1665 ft 3 /min ( m 3 /s) v=0.90 (assumed) PL=0.1 vg = ft 3 /lbm (0.206 m 3 /kg) 3 ft min lbm Wr ft min lb 3 m kg W s r m s kg lbm Wa Wr rw air min kg Wa Wr rw air s m Converting to standard cubic feet/minute (SCFM), where Va= specific volume of air = 13.1 ft 3 /lbm (0.818 m 3 /kg) for dry air at 60 F (15.6 C), SCFM = 13.1(58.1) = 761 ft 3 /min [SCFM = 0.818(0.439) = m 3 /s]. Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 94

108 Appendix F. (Informative) Pipe Hanger Spacing, Hanger Rod Sizing, and Loading This appendix is not part of this standard. It is merely informative and does not contain requirements necessary for conformance to the standard. It has not been processed according to the ANSI requirements for a standard and may contain material that has not been subject to public review or a consensus process. F.1 Recommended maximum spacing of hangers and minimum hanger rod size for steel pipe are set forth in Table F.1. Spacing does not apply where span calculations are made or where concentrated loads such as flanges, valves, specialties, etc. are placed between supports. These tables do not account for seismic, thermal, or other dynamic load considerations. Table F.1 Nominal Pipe Size (in) Maximum Span (ft) Minimum Rod Diameter (in) Up to Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 95

109 F.2 The maximum recommended hanger rod loading based on threaded hot rolled steel conforming is shown in Table F.2. Table F.2 Rod Diameter (in) Maximum Load (lb) Rod Diameter (in) Maximum Load (lb) Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 96

110 Appendix G. (Informative) Hydrostatic Overpressure Relief This appendix is not part of this standard. It is merely informative and does not contain requirements necessary for conformance to the standard. It has not been processed according to the ANSI requirements for a standard and may contain material that has not been subject to public review or a consensus process. NOTE: This Appendix is presented entirely in the English engineering unit system. G.1 Background Hydrostatic overpressures can occur when liquids become confined within enclosed volumes with no gases present. For this to occur, the temperatures of such liquids must be below their boiling points. Liquids such as oil, secondary coolants, and sub-cooled primary refrigerants can become entrapped when certain equipment of a closed-circuit ammonia refrigeration system is isolated from other portions of the system by valves or other means. If there is an increase in temperature in such confined liquids, rapidly rising pressures can occur that are functions of the bulk moduli of elasticity of the liquids. While such increases in temperature and pressure can be very rapid, the corresponding rates of volume increase of the liquids are relatively low. Therefore, relief devices installed to relieve the resulting pressure need not have the flow capacity of vapor relief devices. Practitioners have found that very small relief devices satisfy most requirements for hydrostatic overpressure relief found in refrigeration service. The technical literature available that quantifies such requirements, based on empirical test data, is found almost exclusively in areas of practice that are much more severe than refrigeration service. However, many authorities having jurisdiction require calculations or other evidence to justify selection and sizing of hydrostatic overpressure-relief devices. In those cases, it is acceptable good engineering practice to demonstrate that a relief device having adequate capacity for an extremely severe application will certainly be adequate for less severe circumstances typically encountered in refrigeration applications. The objective is to provide adequate relief, not necessarily to determine exactly how much liquid expansion will occur. In most, if not all cases, the smallest relief valves manufactured for such purposes will have greater flow capacities than the requirements found by calculation for extremely severe circumstances. To address the sizing of orifices needed to relieve hydrostatic overpressure as defined above, an equation for determining the discharge areas of such orifices is stated below: Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 97

111 Q G A 38K K K P P d w v 1 2 Where A = required effective discharge area, in square inches Q = flow rate, in US gallons per minute Kd = effective coefficient of discharge (0.65 for hydrostatic overpressure-relief purposes) Kw = correction factor due to back pressure (1.0 if back pressure is atmosphere or valve responds only to pressure differential across its seat) Kv = correction factor due to viscosity G = specific gravity of the liquid at the flowing temperature P1 = upstream relieving pressure in psig P2 = total back pressure in psig (zero for discharge to atmosphere) Q is determined by the relation: Where BH Q 500 GC B = cubical expansion coefficient per degree Fahrenheit for the liquid at the expected temperature H = total heat of absorption to the wetted bare surface of a vessel, pipe or container in BTU per hour (H = 21,000 A 0.82, where A = total wetted surface in square feet) G = specific gravity of the liquid at the flowing temperature C = specific heat of the trapped fluid in BTU per lb- F Kv is determined as follows: Refer to Figure G1 below to find Kv as a function of the Reynolds number (R), which is defined by the following equation: Where R 12,700Q U A Q = flow rate at the flowing temperature in US GPM U = viscosity at the flowing temperature in Saybolt Universal Seconds A = effective discharge area, in square inches (from manufacturers standard orifice areas) Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 98

112 Figure G1: Capacity Correction Factor K Due to Viscosity Figure G1 was reprinted by permission from Oil and Gas Journal, November 20, 1978 edition. Copyright 1978, Oil and Gas Journal. G.2 Hydrostatic overpressure Relief of ASME Pressure Vessels This section pertains to vessels covered by ASME B&PVC, Section VIII, Division 1, herein referred to as ASME pressure vessels. When ASME pressure vessels contain liquid refrigerant and can be isolated from the other portions of a closed-circuit ammonia refrigeration system, the rules of Section 15.6 apply. However, when ASME pressure vessels contain a non-boiling liquid (i.e., a liquid whose vapor pressure at maximum normal operational, maintenance or standby conditions is less than the relief valve setting), specific requirements of the ASME B&PVC, Section VIII, Division 1 for hydrostatic overpressure-relief valves apply: a. Hydrostatic overpressure- relief valves protecting ASME pressure vessels must bear an ASME UV Code Symbol Stamp. (Code Case BC94-620) b. Hydrostatic overpressure-relief valves protecting ASME pressure vessels must be certified and rated for liquid flow. (Code Case BC94-620) c. Any liquid pressure relief valve used shall be at least NPS 1/2. (UG-128) d. The opening through all pipe, fittings, and non-reclosing pressure relief devices (if installed) between a Copyright 2014 International Institute of Ammonia Refrigeration. All Rights Reserved Page 99