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Applying Safety Standards for Flammable Refrigerants

By Rusty Tharp, Member ASHRAE; Craig Grider, P.Eng., Associate Member ASHRAE; Brian Rodgers; Jennifer Butsch, Associate Member ASHRAE; Jim VerShaw, Member ASHRAE; Greg Relue; Steve Kujak, Member ASHRAE

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© 2021 This excerpt taken from the article of the same name which appeared in ASHRAE Journal, vol. 63, no. 11, November 2021.

About the Roundtable Contributors
Rusty Tharp, Member ASHRAE, senior director of regulatory affairs, Goodman Manufacturing Company | Craig Grider, P.Eng., Associate Member ASHRAE, regional chief engineer—HVAC, refrigeration, and gas appliances, Intertek | Brian Rodgers, principal engineer, heating, cooling and commercial refrigeration, product safety, UL | Jennifer Butsch, Associate Member ASHRAE, director of regulatory affairs, Emerson Commercial and Residential Solutions | Jim VerShaw, Member ASHRAE, chief engineer, residential HVAC & supply, Trane Technologies | Greg Relue, Principal, VRG Consulting LLC, representing Emerson Climate Technologies | Moderator Steve Kujak, Member ASHRAE, director of next generation refrigerant research, Trane Technologies

Refrigerant safety standards and resulting building codes have been very restrictive in the use of flammable refrigerants for HVAC&R products. But as societal demands to control climate change are forcing HVAC designers to consider new lower global warming potential (GWP) refrigerants that are flammable, stakeholders have been working to develop the understanding and practice on how to apply these refrigerants. After more than 10 years, product safety standards and ASHRAE application safety standards are in their final stages of being updated to allow the use of flammable refrigerants.

ASHRAE Journal conducted a roundtable discussion with several industry experts who have been working to update standards related to handling flammable refrigerants.

Moderator Steve Kujak: We’ve been using nonflammable refrigerants for 70, 80 years. What are the major new practices incorporating and handling flammables in the standards?

Rusty Tharp: Many of the same practices we use for the A1s will also apply to flammable A2L, A2 and A3 refrigerants. For example, with A1, these refrigerants are under pressure, so you’ve got to be careful when you’re handling them. You’ve got to keep cylinders upright during transportation, you have to secure the cylinders properly in storage and secure them properly in transportation. A lot of those same rules we use for current refrigerants still apply with A2Ls. Then, while some of the codes and standards are being modified, we do expect that, for A2L refrigerants, much of the storage and transportation requirements are going to be similar.

Craig Grider: The biggest change in practices for refrigerants I’ve been a part of is the development and then utilization of new safety standards for appliances and equipment using flammable refrigerants. I want to start off by pointing out that the development of UL 60335-2-40 [Standard for Household And Similar Electrical Appliances—Safety—Part 2-40: Particular Requirements for Electrical Heat Pumps, Air-Conditioners and Dehumidifiers] was a monumental task for the HVAC industry because the breadth and scope covers a wide range of HVAC products. UL 60335-2-40 has combined under one standard now, products from prior standards such as UL 1995 [Heating and Cooling Equipment], UL 484 [Standard for Room Air Conditioners] and UL 474 [Standard for Dehumidifiers]. So now, we have had to look at products that span from small room air conditioners all the way up to large chillers that operate at thousands of volts. With that, it becomes difficult to look at how we need to apply requirements for the safe use of flammable refrigerants across the entire board of HVAC and refrigeration products.

The main focus currently for most of the industry is A2L refrigerants. We have accepted A2s and A3s into the safety standards, but for now at least, the charge limitations are much lower than those of A2Ls. The industry is going to need to work doing research and updating these standards on a continuous basis as we try to keep up with the new designs and innovative technology that will come with the change to flammable refrigerants. So again for me, this is a huge scope we’re looking at, and that’s why it’s taken over a decade with a lot of research testing and discussions by the industry to get to this point.

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