UL Seeks Feedback on Proposed Changes for A3 and A2L Refrigerant Charge Limits

UL (Underwriters Laboratories), the Northbrook, Illinois (U.S.)-based safety-certification company that publishes appliance standards for the U.S., has released a proposed second edition of the UL 60335-2-89 standard for review, including updated charge limits for hydrocarbon and A2L (less flammable) refrigerants.

UL 60335-2-89 covers safety requirements for commercial refrigerating appliances and ice makers with an incorporated or remote refrigerant unit or motor-compressor.

The proposed standard, which was released June 22 and incorporates CSA (Canadian Standards Association) 60335-2-89, can be accessed at this website, where comments can also be submitted. Comments are due July 24..

After the comments period, UL will review the comments, make adjustments to the standard, and release it for another public comment period before a standard technical panel (STP) votes on the final version. 

Any change to charge limits for flammable refrigerants would have to be adopted by the U.S. Environmental Protection Agency’s SNAP (Significant New Alternative Program (SNAP), noted Christina Starr, Climate Policy Analyst, Environmental Investigation Agency.

Starr anticipates that by March of 2021, UL will publish a final updated UL-2-89 standard. “I hope it will be rapidly adopted by SNAP,” she added.

The proposed standard is a product of CANENA (a standards harmonization body for the Americas) Working Group 12, which, in collaboration with UL and CSA, completed major revisions to UL-60335-2-89. 

The proposed changes in UL 60335-2-89 include a major overhaul of the standard A2L, A2, and A3 allowances; mitigation measures; covered product scope; harmonization with IEC 60335-2-89 3rdEdition; and electrical and mechanical safety requirements for all refrigeration products.  

“The updated standard will be instrumental in allowing the use of flammable, low-GWP refrigerants in the refrigeration sector products,” said the proposal.

 A3 charge limits

The proposed standard follows the publication last year of IEC 60335-2-89, third edition, by the International Electrotechnical Commission, which raised the charge limit for A3 (flammable) refrigerants; in self-contained to 13 times the lower flammability limit (LFL) of the refrigerant;for propane (R290) it increases to 500 g from 150g.

The proposed UL standard similarly calls for raising the charge limit in commercial appliances to 13 times the LFL, but only for open appliances (without doors); it proposes raising the charge limit for closed appliances with doors and/or drawers to eight times the LFL of the flammable refrigerant(300g for R290). 

In addition, the standard proposes that the refrigerant charge of a flammable refrigerant in a self-contained appliance used in a corridor or lobby not exceed three times the LFL.

The higher charge limits would be contingent on an appliance being constructed to prevent flammable refrigerant concentration surrounding the appliance in case of a leak (releasable charge) as verified by the “Annex CC” test.

Commercial appliances also must employ detection/mitigation controls to limit the releasable charge of the system.

A2L requirements

The proposed UL standard would also for the first time include split commercial refrigeration systems, and low-GWP A2L refrigerant requirements for partial units used in field-erected systems, as we'll as commercial refrigeration systems up to 15000 voltage.

The updated standard would also increase the refrigeration charge limits for Class A2L refrigerants. 

While appliances using A2 and A3 flammable refrigerants would be factory sealed self-contained units and fully charged at the factory, “this does not apply to appliances using A2L refrigerants,” says the proposed standard.

Under the proposed standard, field-erected systems consisting of various partial units employing an A2L refrigerant would fall under three charge-limit categories: m1 (13 timesLFL, except for ice makers and products with doors or drawers, for which the limit is eight times LFL; m2 (52 times LFL); and m3 (260 times LFL).

Larger systems with factory-assembled refrigerating circuits using A2L refrigerants can exceed 13 times LFL unless they are: appliances containing one or more refrigerated spaces or compartments; packaged refrigerating units for use in walk-in coolers or freezers; or ice makers. 

Examples of larger systems using A2L refrigerants include refrigeration chillers and refrigeration roof top units (RTUs) for use on refrigerated warehouses. These larger systems would comply with the requirements for partial units using A2L refrigerants.

Like the A3 charge limits, the A2L charge limits are contingent on taking steps and installing equipment to minimize releasable charge.