AHRI Flammable Refrigerants Research Initiative

The HVAC&R industry is transitioning to low GWP refrigerants due to environmental concerns and regulatory requirements . Many of these low GWP refrigerants are classified as lower flammability which has required the update of relevant safety standards and codes to implement these environmentally friendly refrigerants in the field in a timely and cost-effective manner.

Relevant safety standards updates have been underway for many years. The standard revision and code adoption processes are relatively slow while regulations are advancing quickly. This is, in part, because of a lack of publicly available knowledge about the safe use of these refrigerants. To address this challenge, US industry, HVACR society, federal and local governments have collaboratively conducted research to understand the refrigerant flammability and the safe use of these refrigerants for several years. The Air-Conditioning, Heating and Refrigeration Institute (AHRI) has been leading a research program aimed at generating publicly available and sound technical data to support code and standard activities related to the use of flammable refrigerants. This $ 6 million plus program was jointly funded by AHRI, ASHRAE, California Air Resource Board and US Department of Energy. The goal of the research initiative is to deliver scientific findings and produce publicly available technical references to support code and standard activities related to the use of flammable refrigerants.

Underwriters Laboratory and the American Society of Heating and Refrigeration Engineers (ASHRAE) along with stakeholders including industry experts have worked to update the safety standards. AHRI surveyed 46 relevant safety standards’ committees and WGs related to flammable refrigerants for technical data gaps. High priority projects were identified and initiated to understand the refrigerants flammability risk, refrigerant charge quantity, refrigerant detector technologies, mitigation effectiveness and equipment installation. The project reports have been shared with the standard communities and the public and has been used to substantiate changes to safety standards. The list of these projects is attached in Exhibit-1.

The industry is taking a systematic and conservative approach to ensure safe use of flammable refrigerants with a great amount of effort to understand the potential risk. Several whole room-scale refrigerant leak and ignition tests were conducted for air-conditioning and refrigeration products beyond the worst case scenarios with the events unlikely happening by using multiple strong ignition sources placed in locations where combustible mixtures were most likely to occur. In addition, the rapid liquid refrigerant release used in testing is an extremely low-probability type of leak. The testing suggested that, if used, refrigerant detection systems would need a faster response time than the 30 second response originally envisioned by the safety standards. This detection response time change has been adopted by the relevant safety standards such as ASHRAE Standard 15 and UL 60335-2-40. Additional experimental investigation on potential ignition sources inside domestic residence demonstrated that many household ignition sources cannot ignite mildly flammable refrigerants such as burning cigarette, sparks from common household appliances and tools etc.

The industry is continuing its work to further assess the use of mildly flammable refrigerants to inform the continuous upgrading of the safety standards and to confirm previous learnings by other industries already using mildly flammable refrigerants.

Exhibit-1: The following launched projects were developed as the result of the survey of safety standard community. They were prioritized among other identified research needs and considered as high priority projects by a group of experts including industry experts, major safety standard committee chairmen and members, and representatives from U.S. Department of Energy (DOE), Environmental Protection Agency (EPA) and National Institute of Standards and Technology (NIST).