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Flammability of A2L refrigerants and blends at increasing elevations.

Number: 2188

Author(s) : NEWBOULD A., GRUNDY D., SEETON C.

Summary

ANSI/ASHRAE Standard 34, Designation and Safety Classification of Refrigerants prescribes the Refrigerant Classification System, refrigerant concentration limits (RCL) and lower flammable limits (LFL) which are used in applying ASHRAE Standard 15 for system charge densities. A2L refrigerants and blends are weakly flammable, require a high energy ignition source and are mildly energetic when combustion occurs. For some A2L systems they are very close to the transition point where they become A1. It is known that pressures (high and low) can have a significant effect on flammability limits. The heights of major populated cities around the world above sea level ranges from Milan (Italy) at 122m to Denver (Colorado) at 1609m. A range of pure fluids and blends have been tested at varying pressures (altitude) to understand if there is a relationship between pressure and flammable limits. Interestingly for some fluids the flammable limits region is reduced significantly as the pressure is reduced, whereas other fluids show no dependence on pressure whatsoever. In ASHRAE Std 34 (7.4.2) there is an adjustment on the RCL for altitude when expressed as mass per unit volume. Of the fluids tested the data shows there is no negative impact on the flammable range expressed as a v/v%, and for some fluids the flammable window reduces, concluding correcting for altitude on a flammability basis may not be required.

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Pages: 9 p.

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Details

  • Original title: Flammability of A2L refrigerants and blends at increasing elevations.
  • Record ID : 30033070
  • Languages: English
  • Subject: Regulation
  • Source: 2024 Purdue Conferences. 20th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2024/07/17

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