ASHRAE Standard 15: Proposed Changes to Incorporate 2L Refrigerants

Transcription

1 ASHRAE Standard 15: Proposed Changes to Incorporate 2L Refrigerants Phillip Johnson, P.E. ASHRAE Member McQuay International Staunton, VA San Antonio, Texas 2012 Annual Conference

2 Learning Objectives for this Session Describe the changes to ASHRAE Standard 15 that are under consideration to allow the use of 2L refrigerants. Describe the changes to ISO 5149 and EN 378 that are under consideration to allow the use of 2L refrigerants. Describe the changes to UL Standards that are under consideration to allow the use of 2L refrigerants. Provide a comparison of the approaches being proposed in the US and the EU relative to the application of mildly flammable refrigerants. Provide well informed comments on proposed changes to ASHRAE, ISO, and UL Standards when they are circulated for public review. Describe the risks of 2L refrigerants relative to class 2 and 3 refrigerants. ASHRAE is a Registered Provider with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to ASHRAE Records for AIA members. Certificates of Completion for non AIA members are available on request. This program is registered with the AIA/ASHRAE for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.

3 Seminar 11 Standards d Development tfor 2L Flammable Rfi Refrigerants 1. ASHRAE Standard 15: Proposed Changes to Incorporate 2L Refrigerants 2. ISO 5149, IEC : Proposed Changes to Incorporate 2L Refrigerants 3. UL's Effort to Harmonize Product Safety Requirements for A2L, A2, and A3 Refrigerants

4 Introduction Environmental considerations are reducing the number of chemicals that can be used as refrigerants. The HFCs were introduced to replace ozone depleting CFCs and HCFCs, but they are greenhouse gases and are subject to use restrictions in some countries. As a result the industry is evaluating chemicals with very low global warming potential. Some of these chemicals are mildly flammable and have been assigned to a new flammability safety classification, 2L, in ASHRAE Standard 34. This seminar provides information on the changes to standards that specify requirements for the use of 2L flammable refrigerants. Type of standards US Europe International Refrigeration Safety ASHRAE 34 Classification UL ISO 817 System Safety ASHRAE 15 EN 378 ISO 5149 Equipment Safety UL 207 UL 250 UL 471 UL 474 UL 484 UL 984 UL 1995 UL UL EN EN IEC IEC

5 Abbreviations & Nomenclature AIT = Auto Ignition Temperature ATEL = Acute Toxicity Exposure Limit CFD = Computational Fluid Dynamics FCL = Flammable Concentration Limit FDIS = Final Draft International Standard HOC = Heat Of Combustion LEL/UEL = Lower/Upper Explosion Limit LFL/UFL = Lower/Upper Flammability Limit LOC = Limiting iti Oxygen Concentration ti MIE = Minimum Ignition Energy ODL = Oxygen Deprivation Limit RCL = Refrigerant Concentration Limit S U = Burning Velocity

6 What Are 2L Refrigerants? A safety group classification used by several refrigerant designation standards: ASHRAE Standard ISO 817:201x (draft, FDIS registered dfor formal approval, will replace ISO 817:2005) from: ASHRAE Standard

7 Flammability Classifications from: ASHRAE Standard

8 What Are 2L Refrigerants? ity Limit Low wer Flammabili (kg/m³) 0.1 Subclass 2L Class 2 Class 3 Heat of Combustion (kj/kg) Exhibit flame propagation when tested at 60 C LFL > 0.10 kg/m³ HOC < kj/kg S U 0.1 m/s 0.1 Maximum Burning Velocity (m/s) flame propagation tests per ASTME 681 burning velocity test methods in final process of standardization (ASHRAE RP 1583, RP 1584)

9 Current 2L Refrigerants Per ASHRAE , Addendum h, Addendumi: A2L B2L R 32 R 717 R 143a R 1234yf R 1234ze(E) Future possibility of blends (R 4xx or R 5xx) or other single component refrigerants.

10 Brief History of 2L Initiated by ISO 817 (first proposal started 1999) Removed from final draft of ISO 817:2005 (insufficient consensus at that time) Continued to develop within ISO (817 and 5149) and ASHRAE ASHRAE Addendum ak (2009 public review, published 2010) ASHRAE included Subclass 2L ASHRAE Addenda h and i established five 2L refrigerants ISO FDIS 817:201x will include Subclass 2L (to be published 2012 or 2013)

11 Risks of Flammable Refrigerants Quantitative Risk Assessment Methods Risk = Probability Severity Probability of an event occurring: Fuel: refrigerant leak or release into air: LFL UFL, LOC (range Oxidant: Ignition sources: presence, quantity, energy level (MIE, AIT); may be electric or thermal of flammable limits); size of flammable volume or region that may change size and location versus time Severity of an event when it occurs: Energy release: Quantity: HOC Rate: S U (chemical reaction rate); LEL UEL (range of explosion limits) Pressure rise

12 Risks of Flammable Refrigerants ASHRAE Research (active projects) RP 1580: Study of Input Parameters For Risk Assessment of 2L Flammable Refrigerants in Residential Air Conditioning and Small Commercial Refrigeration Applications RP 1583: Assessment of Burning Velocity Test Methods RP 1584: Assessment of Alternative Approaches to Predicting theburning Velocity of a Refrigerant

13 Risks of Flammable Refrigerants ity Limit Low wer Flammabili (kg/m³) 0.1 Increasing probability of a combustion event Subclass 2L Class 2 Class Maximum Burning Velocity (m/s) Heat of Combustion (kj/kg) Increasing severity of a combustion event

14 Risks of Flammable Refrigerants Standard d currently includes udessafety requirements for Class 2 and Class 3 refrigerants Most of the requirements have existed for many years Not always developed using a quantitative approach (no formal risk assessment calculations) Reasonable success if looking back over time (empirical justification) Relatively conservative (risk averse relatively restrictive) SSPC 15 now working to determine what can be relaxed dto safely fl allow more broad use of 2L refrigerants

15 Development of Safety Standards Many industries must address safety issues, and develop appropriate standards and guidelines One possible development process: ISO/IEC Guide 51 Safety aspects Guidelines for their inclusion in standards provides standards writers with guidelines for the inclusion of safety aspects in standards applicable to any safety aspect related to people, property or the environment aimed at reducing theriskarising fromtheuseofproducts of products, processesorservices or services considers thecomplete life cycle ofa product, process or service, including both the intended use and the reasonably foreseeable misuse safety is achieved by reducing risk to a tolerable level SSPC15 not formally adhering to Guide 51, but taking a similar approach

16 Development of Safety Standards ISO/IEC Guide 51

17 ASHRAE Standard 15 Overview Basis of Standard Refrigerant Safety Classification Class 1 Nonflammable Class 2 Lower Flammability Class 3 Higher Flammability Occupancy Classification Institutional Public assembly Residential Commercial Class A Lower Toxicity Class B Higher Toxicity Large mercantile Industrial Mixed Refrigerating System Classification Direct Indirect (open or closed) Restrictions onrefrigerant Use Installation Restrictions High probability Low Probability Design and Construction of Equipment & Systems Operation and Testing must address each possible combination of classifications

18 Risk Management Risk assessment Quantitative analysis becomes very specific to each application, each scenario, each equipment type SSPC 15 has reviewed quantitative flammability test data and some CFD modeling, but has taken more of a qualitative approach to risk assessment Complexity due to the scope of the standard

19 Safety Factor RCL = min(atel, ODL, FCL) FCL = 25% LFL Refrigerant RCL Source R 32 FCL R 143a FCL R 717 ATEL R 1234yf R 1234ze(E) Safety Factor = 4 relative to LFL (margin to limit) Standard 15 methodology assumes catastrophic release of largest refrigerant circuit into available volume of occupied space with instantaneous mixing Does not directly consider flammable volume versus time or leak rate, so event probability is not zero FCL FCL

20 Standard 15 Approach to 2L

21 Standard Addendum a SSPC 15 issued a draft of revisions to obtain comments and feedback SSPC 15 now working to address several issues Upcoming slides will show selectionsfrom the APR, but not more recent revisions now in process

22 Standard

23 in general, it is very restrictive Class 2 & 3 Restrictions includes 2L, because 2L is sub class of class 2 high probability system is defined as: thi ti ll this exception allows small self contained systems, with some restrictions on where it may be located, see next page

24 but this means split systems are generally not allowed due to field installed refrigerant tubing/piping, with exception for use of companion or block valves in general, it is very restrictive Class 2 & 3 Restrictions so current revision allows use of A2 or A2L refrigerants in self contained systems with less than 3kg or 10kg, depending on location in the building and depending on the occupancy (usage) of the building see next page for definitions of various occupancies

25 Occupancy Definitions where A2 or A2L is currently allowed or not allowed in some form or fashion (i.e. with restrictions) (Class 3 is much more restricted)

26 in general, it is very restrictive Class 3 Restrictions

27 Proposed A2L Restrictions intent is to allow A1 and A2L for human comfort, with restrictions as shown on next page

28 Additional Proposed A2L Restrictions as first step towards less restrictive use of 2L refrigerants, these requirements were proposed in the APR revisions in process now may further change the requirements based on more risk assessment and risk analysis, to address issues such as: (1) reliability of detection & ventilation systems, (2) hot surface temperature limit, (3) ignition source restrictions

29 Basic Approaches to Using Class 2L Ignition source restrictions in all cases Locate equipment outdoors & use indirect system If equipment is indoors, or an outdoor direct system: Remove or revise the upper cap limit on total flammable refrigerant on site Continue to use RCL to limit charge size in each independent refrigerant circuit Safety margin to LFL included in RCL Refrigerant detection and ventilation requirements in the occupied space

30 Additional Issues changing Standard 15 is only the first step, next step is changing model dl building codes, after that next step is state and local codes must adopt model codes and/or Standard 15 without changes to UL standards (such as UL1995, UL984, UL , pending draft UL , etc.), to clearly identify equipment design requirements for class lass2l fluids, it will be difficult to receive product safety listing from UL or ETL, without listing label on the equipment it is difficult to persuade the local code official to allow the installation

31 Institutional Occupancy Issues buildings with institutional occupancy are generally places where people have restricted ability to move by themselves, thus preventing them from escaping in case of emergency because of increased risk for prolonged exposure, in the event of a refrigerant release, the refrigerant charge quantity limits i for institutional i i occupancy is reduced to half the normal limit so section is an exception to , and this exception makes it more restrictive for institutional occupancy (total from500kg to 250kg, and from 100% RCL to 50% RCL)

32 Institutional Occupancy Issues if refrigerant charge quantity limits (50% of RCL) seem too restrictive, counter measure is to change the building design to make separate sections, each using separate HVAC system (independent refrigerant circuits)

33 Timeline SSPC 15 Activities 21-Jun ~ Aug Jan-2012 Feb~Apr Jun-2012 To Be Determined SSPC 15 creates ad hoc working group to evaluate changes required in Standard 15 to accommodate class 2L, based on report that SSPC 34 was evaluating a change proposal to create subclass 2L ad hoc working group studies issues and develops proposed revisions public review period ends for APR of Addendum a SSPC 15 reviews ad working group results after incorporating feedback from public review comments SSPC 15 interim teleconference meetings, further discussion and work on the committee draft, sends back to ad hoc working group ad hoc working group meeting and report back to SSPC 15 first Publication Public Review (PPR1)

34 Interaction with Building Codes Code Change Cycles 2012 editions i published during 2011 (IMC, IFC) and 2012 (UMC)

35 Change Cycles Standard is Continuous Maintenance anyone can submit change proposals at any time, SSPC15 committee reviews and can modify, accept, or reject consensus based with a public review process addenda d published on continuous basis every 3 years publish an updated edition, including all addenda approved since the prior edition 2001, 2004, 2007, , 2016

36 Standard the estandard d is referenced eee cedby, or adopted in part/whole, or copied into various building codes National model building codes that are then adopted dby individual id ljurisdictions, such as: International Mechanical Code( IMC ) International Fire Code ( IFC ) Uniform Mechanical Code ( UMC ) State building codes Local building codes, where applicable developed by ICC developed eloped by IAPMO Model lbuilding codes are published once every three years, following a fixed process during each code changecycle cycle ICC = International Code Council IAPMO = International Association of Plumbing and Mechanical Officials

37 Code Change Cycles In the past, the ASHRAE cycle for code intended standards was leading the model building code cycles (ASHRAE published first, just before the beginning of a 2 year cycle for building codes). The ICC changed their hicycle (split into two groups of codes, each with a separate cycle time line). Now there is a conflict with ASHRAE. Cycle 1 Cycle 2 Cycle 3 Cycle 4 future? future? Std 15 IMC UMC IFC

38 Code Change Cycles ICC 2012/2013 Code Development Cycle will result in the 2015 I Codes (published during 2014) The cycle was changed from past practice, this is the first time the codes will be split into two groups (A/B) with a Code Development Hearing and Final Action Hearing in both 2012 (Group A) and 2013 (Group B). Now also Group C. Code change cycle for the 2015 edition started deadlines dli for change proposal submission i IMC IFC UMC 3 Jan Jan Jan 2013 Due to revised process by ICC, ASHRAE is not correctly synchronized p y, y y with ICC schedule. ASHRAE CIS considering how to respond.

39 Code Change Cycles If safety requirements for class 2L refrigerants are not added to the 2015 building codes, the next opportunity is the 2018 edition Adoption & effective date by individual states or localities will be at different times 39

40 Bibliography ANSI/ASHRAE Standard , Safety Standard for Refrigeration Systems, American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc., Atlanta, GA ANSI/ASHRAE Standard d , Designation and Safety Classification of Refrigerants, American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc., Atlanta, GA ISO/IEC Guide 51:1999, Safety aspects Guidelines for their inclusion in standards. ISOGuide 73:2009, Risk management Vocabulary. ISO DIS 817, Refrigerants Designation and safety classification, International Organization for Standardization, 2010.

41 Questions? Phillip Johnson hll h