February 2022 | March 2022 REFRIGERANTS 18 Volume 8 No.2 With the exception of the low-pressure refrigerants and carbon dioxide, all the refrigerants with a GWP less than 250 have a degree of flammability which, under current standards and regulations, may require additional safety measures for use. These measures may be as simple as ensuring the refrigerant change size falls within acceptable limits (BS EN 378-1:2016+A1:2020) or may require higher brazing qualifications and involvement of notified bodies (Pressure Equipment Safety Regulations 2016). Standards and regulations These have been in place for several years and equally apply to the essentially non-toxic, non-flammable (A1) higher GWP refrigerants as well as the low GWP flammable, toxic and high-pressure explosive refrigerants being considered today. The main di erence is that with the previous A1 refrigerants, the safety boundaries were often well beyond the conditions of use. With the A2L, A3 and B2L safety class refrigerants these boundaries are now much closer and sometimes overlap requiring additional safety measures to be taken to ensure safe use. Guidance on refrigerant charge size can be found in several application specific standards or, for general refrigeration or human comfort applications, BS EN 378:2016, with aids such as the Climalife A2L charge calculator online tool (www.a2l.climalife.com ) available to interpret and apply the guidance. Maximum charge sizes vary dependent on refrigerant, access category, system location category and whether additional protective measures are employed or not. Although less than the higher GWP A1 refrigerants, charge sizes with A2L refrigerants can be as high as 84kg with additional protective measures and up to 17kg without any additional protective measures. The pressure equipment safety regulation (PE(S)R) is also a key consideration and a legal requirement. At present PE(S)R only considers flammable and non-flammable i.e., there is no consideration of lower or higher flammability, R-1234yf is treated the same as R-290. Apart from R-1234ze, all the A2L As the F-Gas regulation drives the industry to lower and lower GWP refrigerants, for those not already familiar with the requirements when using flammable refrigerants, there is no escaping the need to upskill and learn about all the requirements to safely handle and use them. Even if it is decided to stay with non-flammable and use R-744, the brazing and notified body requirements are still a factor due to the very high pressure experienced in R-744 systems. Figure 1 – Maximum refrigerant charge sizes calculated using EN 378 for an access category a, location category I or II refrigeration application without additional protective measures.