chan The Electronic Newsletter of The Industrial Refrigeration Consortium Vol. 14 No. 2, 2014 STANDARDS UPDATE ASHRAE PUBLISHES THE 2013 EDITION OF STANDARD 15 ASHRAE Standard 15 - Safety Standard for Refrigeration is one of ASHRAE s oldest standards. This year will mark the 100 th anniversary when a group of industry professionals formed a committee that sought to improve refrigeration system safety by developing a safety code that would, eventually, become ASHRAE Standard 15. We won t review the history of this standard but in this edition of The Cold Front, we highlight changes that were incorporated into the latest edition of Standard 15 published by ASHRAE in December 2013. In addition, we will provide an overview of Addendum a to the 2013 edition of Standard 15 approved by ASHRAE in January this year. ASHRAE 15-2013 In December 2013, ASHRAE released an updated version of its Standard 15 Safety Standard for Refrigeration. The 2013 edition fully incorporates a series of changes that were made through continuous maintenance 1 of the 2010 edition of Standard 15. Table 1 provides a summary of the 2010 edition of Standard 15 that were incorporated into the 2013 edition. IRC Staff Director Doug Reindl 608/265-3010 or 608/262-6381 dreindl@wisc.edu Assistant Director Todd Jekel 608/265-3008 tbjekel@wisc.edu Research Staff Dan Dettmers 608/262-8221 djdettme@wisc.edu John Davis jgdavis@epd.engr.wisc.edu In This Issue Standards Update 1-6 Upcoming Ammonia Classes 2 Noteworthy 2 IRC Staffing Update 7 IRC Contact Information Mailing Address Toll-free 1-866-635-4721 1513 University Avenue Phone 608/262-8220 Suite 3184 FAX 608/262-6209 Madison, WI 53706 e-mail info@irc.wisc.edu Web Address www.irc.wisc.edu
Machinery Room Ventilation Inlets The purpose of a machinery room mechanical ventilation (exhaust) system is to effectively remove potentially contaminated air from the machinery room space and expel that air to a safe outdoor location. In the event a refrigerant leak occurs within the machinery room, the mechanical ventilation system is expected to effectively remove the refrigerant laden air from the machinery room in order to help protect both personnel and infrastructure. The section of Standard 15 that establishes requirements for mechanical ventilation of machinery rooms is 8.11.4 and changes to the 2013 edition included an added clarification to locating the exhaust intakes to help mitigate the effects of refrigerant leakage within the machinery room. The following text was added to 8.11.4 The mechanical exhaust inlet(s) shall be located in an area where refrigerant from a leak is likely to concentrate, in consideration of the location of the replacement air path(s), refrigerating machine(s), and the density of the refrigerant relative to air. For heavier-than-air refrigerants, the inlet to the machinery room exhaust would be placed low within the machinery room space (presumably, ducting would be utilized to achieve this positioning) and in a location were the refrigerant would likely accumulate or concentrate. In addition, the inlet has to be suitably separated from the location where make-up air to replace the exhaust air is introduced to prevent short-circuiting. For lighter-than-air refrigerants like ammonia, the inlet to the machinery room exhaust would be placed high within the space. Most ammonia machinery rooms have the exhaust inlets located at or near the ceiling of the space. The addition to 8.11.4 did not include more specificity on the exact location of the exhaust inlets because of the variability in machinery room layouts and designs. Rather, the change provides key attributes of the intended function of this safety system while giving the designer flexibility to implement the mechanical exhaust system on a case-by-case basis. Upcoming Ammonia Courses Refrigerant Inventory Calculation Brown Bag August 6 2014 Online Design of NH 3 Refrigeration for Peak Performance and Efficiency September 8-12, 2014 Madison, WI Process Hazard Analysis for Ammonia Refrigeration September 24-26, 2014 Madison, WI Introduction to Ammonia Refrigeration October 8-10, 2014 Madison, WI Principles and Practices of Mechanical Integrity for Ammonia Refrigeration November 5-7, 2014 Madison, WI Intermediate Ammonia Refrigeration December 3-5, 2014 Madison, WI Process Safety Management Audits for Compliance and Continuous Safety Improvement January 12-14, 2015 Madison, WI Introduction to Ammonia Refrigeration March 4-6, 2015 Madison, WI Ammonia Refrigeration System Safety April 13-15, 2015 Madison, WI Noteworthy Visit Send the items IRC of website note for to next access newsletter presentations to Todd made Jekel, at the 2011 tbjekel@wisc.edu. IRC Research and Technology Forum. Mark your calendars now for the 2012 IRC Research and Technology Forum May 2-3, 2012 at the Pyle Center in Madison, WI. Send items of note for next newsletter to Todd Jekel, tbjekel@wisc.edu. 2
Design Pressure The 2013 edition of Standard 15 now defines design pressure as: the maximum gauge pressure for which a specific part of a refrigerating system is designed. The change simply included the addition of gauge as a descriptor to pressure for clarification. This small change also aligns Standard 15 with companion standards such as the ASME Boiler & Pressure Vessel Code (Section VIII Division 1) and the ASME Piping Code (B31.5) both of which Standard 15 references a normative requirements. For example, Section VIII Division 1 of the ASME B&PV Code refers to design pressure as the the maximum difference in pressure between the inside and outside of a vessel (UG-21). Although the ASME Piping Code (B31.5) does not use the same language in reference to the design pressure, gauge pressure is implied as reference to specific design pressure values are cited as such (e.g. 505.1.1). Table 1: Revisions incorporated into the 2013 edition of ASHRAE Standard 15. Applicable Description Comment Section Clarifies requirements for machinery room ventilation exhausts to better enable refrigerant removal in the event of a leak. 8.11.4 This change is intended to ensure that refrigerant leaks will be effectively removed from machinery room spaces. Clarifies the definition of design pressure as expressed in gauge pressure. 3 Adds requirement to secure or lock refrigerant access ports located outdoors. 11.3.1 Although gauge pressure was implied for the units of pressure previously, this change removed any ambiguity. This change was made to harmonize ASHRAE 15 with a similar change made to the International Mechanical Code. Removes informative Appendix A that provided guidance for allowable refrigerant concentrations for mixtures. Appendix A Appendix A is deleted in its entirety and the requirements for determining refrigerant concentration limits is addressed by ASHRAE 34. Eliminates the requirement for manual discharge or diffusion arrangements for ammonia refrigeration systems. 8.13 This change was intended to complete changes made to the 2007 edition of Standard 15 that removed Appendix B Guidelines For Emergency Discharge of Refrigerants when Required by Local Codes Secure Refrigerant Access The 2013 edition of Standard 15 adds a new section (11.3.1) that requires the securing of refrigerant circuit access ports located outdoors. This change was intended to harmonize Standard 15 with the International Mechanical Code. The last edition (2012) of the IMC was modified to include the following requirement: 1101.10 Locking access port caps. Refrigerant circuit access ports located outdoors shall be fitted with locking- 1 Continuous maintenance is a process ASHRAE uses for several of its standards that undergo frequent revision. When ASHRAE approves these changes under the continuous maintenance process, they are published periodically and then fully incorporated into the standard once every three years. 3
type tamper-resistant caps or shall be otherwise secured to prevent unauthorized access. (IMC 2012) The Standard 15 modification is not as specific with the exact means of securing (i.e. it does not prescribe locking-type tamper-resistant caps ) simply because the application of Standard 15 is not limited to systems that would utilize this type of device such as unitary or split system air conditioners. The motivation for this change to both the IMC and Standard 15 is the result of thieves accessing unlocked access ports to huff the refrigerant. Although ammonia systems are generally not susceptible to huffing (or at least repeated huffing), securing external access to refrigerant containing parts of these systems by unauthorized personnel has been routine for quite some time due to recurring ammonia thefts intended to support clandestine drug manufacturing (EPA 2000). Refrigerant Concentration Limit Calculations ASHRAE Standard 34 - Designation and Safety Classification of Refrigerants is a companion standard to ASHRAE 15. Standard 34 is the repository of information that relates to the health and safety risks of refrigerants used in HVAC&R systems. Historically, Standard 15 would repeat key information related to safety classifications of individual refrigerants but with the proliferation of new refrigerants being introduced, it was impossible for Standard 15 to remain current. To address this challenge, ASHRAE removed the Standard 34 information that was duplicated in Standard 15 and beginning in 2007, ASHRAE began to bundle the sale of both Standard 15 and Standard 34. The intent of bundling was to ensure that users of Standard 15 had the most current information on both refrigerant designations and safety classifications (per Standard 34) and vice versa. A final step in this process was to remove an informative appendix (Appendix A) in ASHRAE 15 which included guidance on calculating Refrigerant Quantity Limits (RQLs) for blends. As part of the changes in the 2013 edition, Appendix A has been removed in its entirety and these details are now included in Appendix G and Section 7.2 of Standard 34. In addition, Standard 34 has transitioned from RQLs to Refrigerant Concentration Limits (RCLs). Refrigerant Discharge The last revision to the 2013 edition of Standard 15 involved removing section 8.13 in its entirety. Section 8.13 required ammonia systems to be fitted with manual emergency discharge or diffusion arrangements for discharging refrigerant from the system in the event of an emergency. The so called fireman s dump station never fully delivered on its promise of enhanced system safety and was eliminated as a requirement from model codes such as the International Fire Code and the International Mechanical Code. As an alternative to the manual emergency discharge, ANSI/IIAR 2-2008 was modified to incorporate a provision in ammonia refrigeration applications referred to as the Emergency Pressure Control System (EPCS). Those interested can refer to Appendix K (informative) of IIAR 2 for more details on the EPCS. Addendum a to ASHRAE 15-2013 In January 2014, ASHRAE issued Addendum a for immediate publication. Addendum a to Standard 15includes modifications to the portion of the standard that deals with discharge requirements for pressure relief systems (specifically, section 9.7.8). In addition, prior versions of ASHRAE 15 included mandatory requirements for pressure relief vent systems found in Appendix D. Changes to Standard 15 by Addendum a bring forth those requirements into a new section now residing within the body of the standard in a new section 9.7.9. Addendum a also added clarifying language to ensure users understand design requisites of relief vent systems. The following are highlights of Addendum a to Standard 15. Relief Vent Discharge Location When various criteria are met, ASHRAE 15 requires venting of relief devices to a safe location outside of a building. The most frequently implemented option is relief vent piping systems discharging directly to 4
atmosphere terminated at a location not less than 15 ft (4.57 m) above the adjoining ground level (per 9.7.8.2 a.) and not less than 20 ft (6.1 m) from windows, building ventilation openings, pedestrian walkways, or building exits. (per 9.7.8.2 b.). In this new revision to Standard 15, systems containing refrigerants with a safety group classification A1 are now permitted to discharge at any elevation where the point of discharge is located in an access-controlled area accessible to authorized personnel only based on a newly added exception to part a. of 9.7.8.2. Part c. of 9.7.8.2 also emphasizes the 20 ft separation distance from below-grade walkways, entrances, pits or ramps must be met when a discharge of heavier-than-air refrigerants would yield a concentration greater than the ASHRAE 34-designated refrigerant concentration limit (RCL) in those locations. Part f. of 9.7.8.2 adds a requirement for the inclusion of a drip pocket to relief vent lines that terminate vertically upward to prevent the accumulation of moisture in the vent system. The drip pocket must be installed at the first change in direction and have a minimum depth of 24 inches (0.6 m). The drip pocket must also be fitted with a valve or drain plug to facilitate removal of any accumulated moisture in the vent line. Maximum Allowable Back Pressure In 2000, ASHRAE modified the requirements for pressure relief vent lines. Specifically, a new equation for the maximum allowable equivalent length of a relief vent line was incorporated. Formerly appearing as equation D-1 in normative Appendix D of Standard 15 (shown below), this line length limit equation has been the source of much confusion. (ASHRAE 15-2013 Appendix D) Section 9.7.9.3.1, now included in Standard 15 with Addendum a, modifies language to make clear that the key performance criterion is not necessarily the resulting length that one might calculate using the above equation, rather, the key performance criterion is the back pressure due to flow in the vent piping system and other sources of back pressure affecting the vent pipe system (such as the presence of treatment systems that may impose additional superimposed back pressure effects). Most industrial refrigeration systems have a network of piping attached to multiple relief valves in what is commonly referred to as a headered or manifolded relief vent system. Addendum a adds section 9.7.9.3.3 which requires designers ensure that relief vent systems having two or more relief devices does not result in the back pressure on each relief device expected to operate simultaneously does not exceed the maximum allowable back pressure as-specified by the valve manufacturer or in accordance with Section 9.7.9.3.2 based on the relief device type. Conventional relief valves have their maximum allowable back pressure limited to no more than 15% of the valve s set pressure. The addition of Section 9.7.9.3.3 is intended to clarify that the back pressure limit is applicable to not only each individual relief device itself but to the piping affixed to the outlet of relief valves on a headered system that may simultaneously actuate which may necessitate larger common sections of the vent system to prevent the build-up of pressure beyond the maximum limit. A full version of Addendum a to Standard 15-2013 can be downloaded directly from the ASHRAE website at: https://ashrae.org/file%20library/doclib/stdsaddenda/15_2013_a_20140131.pdf. 5
Conclusion Industry codes, standards, and guidelines do change periodically. It is important for users of these documents to stay current on the changes as they occur. Even more important is for those who are affected by these standards to become engaged with their development, public review, and continuous improvement. Postscript - IIAR 2 ANSI/IIAR 2 is a standard that provides minimum requirements for equipment, design and installation of closedcircuit ammonia refrigerating systems. The IIAR Standards Committee (SC) is currently in the process of updating and expanding its Standard 2 - Equipment, Design, and Installation of Closed-Circuit Ammonia Mechanical Refrigerating. Part of the revisions being sought with an updated version of this standard is its transition to a safety standard as opposed to being a design standard. The first public review of IIAR 2 took place at the end of 2013 and the IIAR SC is in the process of addressing the comments received from that first public review in preparation for submitting a revised version of this standard for a second public review. Refer to the standards review portion of the Technology & Standards tab on the IIAR website (www.iiar.org) for details and updates on this and other IIAR standards. References ASME Section VIII Division I, Boiler and Pressure Vessel Code Section VIII Division I, American Society of Mechanical Engineers, New York, NY, (2013). ASME B31.5, Refrigerant Piping and Heat Transfer Components, American Society of Mechanical Engineers, New York, NY, (2013). ANSI/ASHRAE 15, Safety Standard for Refrigeration, ASHRAE, Atlanta, GA (2013). ANSI/ASHRAE 34, Designation and Safety Classification of Refrigerants, ASHRAE, Atlanta, GA (2013). ANSI/IIAR 2, Equipment, Design, and Installation of Closed-Circuit Ammonia Mechanical Refrigerating, International Institute of Ammonia Refrigeration, Arlington, VA, (2008) 2. EPA, Anhydrous Ammonia Theft, U.S. Environmental Protection Agency publication EPA-F-00-005, http://www.epa.gov/osweroe1/docs/chem/csalert.pdf, March (2000). IFC, International Fire Code, International Code Council, Country Club Hills, IL (2012). IMC, International Mechanical Code, International Code Council, Country Club Hills, IL (2012). 2 IIAR has issued two addenda to this standard. The latest version of ANSI/IIAR 2-2008 is Addendum B which was released in December 2012. 6
IRC Staffing Update Marc Claas Since August 2009, Marc Claas has been an active staff researcher at the IRC. Initially joining the IRC as a volunteer researcher after receiving his B.S. in Mechanical Engineering from the University of Wisconsin- Platteville, Marc continued his studies at the University of Wisconsin-Madison part-time while working at the IRC full-time. Marc completed his Masters of Engineering in Energy just a bit more than two years ago. In addition to supporting the IRC s research activities, Marc was an active behind the scenes contributor to the IRC s education efforts as well. In May this year, Marc elected to move on to the next phase of his career and we will miss him at the IRC. On behalf of the IRC staff and members, I would like to extend a sincere thanks to Marc for his work here and we all wish him well in his future endeavors. John Davis On July 1, 2014, John Davis joined the IRC as a part-time research staff member. In addition to his work with the IRC, John will continue as a program director in the University of Wisconsin-Madison s Department of Engineering Professional Development. John is a mechanical engineering graduate from Iowa State University and he also holds two masters degrees: one in engineering management from Northwestern and a second in engineering from Purdue University. John comes with significant industry experience having spent time in product development roles at the Trane Company, Bell and Gossett, and Research Products. Prior to joining the UW, John was a project engineer with the contracting firm of Kilgust Mechanical in Madison. John holds a number of credentials including a LEED AP and Six Sigma Black Belt. In addition, he is a registered Professional Engineer in the State of Wisconsin. We are looking forward to John coming on board and making significant contributions to the industry! 7