I have joked about this topic in other posts, as we have been battling the idea that our new refrigerant for vehicle air conditioners is a Category 1 Flammable Gas. This conversion from R-134a has been a bumpy one, but in jest, I share with you EPA’s “use conditions,” and for an agency that certainly played along with industry, they sure did have some requirements that sound a lot like a PSM covered process…
HFO–1234yf MVAC systems must adhere to all of the safety requirements of SAE 1 J639 (adopted 2011), including:
- requirements for a flammable refrigerant warning label,
- high-pressure compressor cutoff switch,
- pressure relief devices, and
- unique fittings.
For connections with refrigerant containers of 20 lbs or higher, use fittings consistent with SAE J2844 (adopted 2011).
NOTE: the fittings will be quick-connect fittings, different from those for any other refrigerant
Manufacturers must conduct Failure Mode and Effect Analysis (FMEA) as provided in SAE J1739 (adopted 2009). Manufacturers must keep the FMEA on file for at least three years from the date of creation.
EPA in their own words:
The first use condition requires that MVAC systems designed to use HFO–1234yf must meet the requirements of the 2011 version of the industry standard SAE J639, ‘‘Safety Standards for Motor Vehicle Refrigerant Vapor Compression Systems.’’ Among other things, this standard sets safety standards that include unique fittings to connect refrigerant containers to the MVAC system; a warning label indicating the refrigerant’s identity and indicating that it is a flammable refrigerant; and requirements for engineering design strategies that include a high-pressure compressor cutoff switch and pressure relief devices. This use condition also requires that fittings for refrigerant containers of 20 lbs or greater will be consistent with SAE J2844 (same fittings as for low-side service port in SAE J639).
The second use condition requires the manufacturer of MVAC systems and vehicles (i.e., the original equipment manufacturer [OEM]) to conduct and keep records of a risk assessment and failure Failure Mode and Effects Analysis (FMEA) for at least three years from the date of creation. There is an existing industry standard, SAE J1739, that gives guidance on how to do this. It is standard industry practice to perform the FMEA and to keep it on file while the vehicle is in production and for several years afterwards (U.S. EPA, 2010a).
EPA had initially proposed “use conditions” requiring the concentration of HFO–1234yf was NOT to exceed the lower flammability limit (LFL) in the passenger compartment free space for more than 15 seconds, and the engine compartment, the concentration of HFO–1234yf was not to exceed the LFL for any period. A third proposed use condition, which also addressed the engine compartment, would have required protective devices, isolation and/or ventilation techniques in areas where there is a potential to generate HFO–1234yf concentrations at or above 6.2% volume to volume (v/v) in proximity to exhaust manifold surfaces and hybrid or electric vehicle electric power sources.
EPA concluded that the use conditions in the final rule address the risks from both HF and flammability. Industry standard SAE J639 (adopted 2011) provides for a pressure relief device designed to minimize direct impingement of the refrigerant and oil on hot surfaces and for the design of the refrigerant circuit and connections to avoid refrigerant entering the passenger cabin. These conditions are intended to mitigate risks of HF generation and ignition. The pressure release device ensures that pressure in the system will not reach an unsafe level that might cause an uncontrolled, explosive leak of refrigerant, such as if the air conditioning system is overcharged. The pressure release device will reduce the likelihood that refrigerant leaks would reach hot surfaces that might lead to either ignition or formation of HF. Designing the refrigerant circuit and connections to avoid refrigerant entering the passenger cabin ensures that if there is a leak, the refrigerant is unlikely to enter the passenger cabin. Keeping refrigerant out of the passenger cabin minimizes the possibility that there would be sufficient levels of refrigerant to reach flammable concentrations or that HF would be formed and transported where passengers might be exposed.
Source: Federal Register / Vol. 76, No. 60 / Tuesday, March 29, 2011, / Rules and Regulations