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By Alan Jackson, BJA Refrigeration Consultants
There are an increasing number of new low GWP refrigerants being placed on the market. Exhibiting similar performance properties to HFC refrigerants, a big attraction is their lower global warming potential, which over the coming years will become crucial in meeting EU 517/2014 – the revised F-gas regulations. Such low GWP refrigerants are often flammable and are classified by ASHRAE as A2L. The table below offers a simplified guide to refrigerant classification.
A2L refrigerants exhibit low toxicity and are mildly flammable, but what does this mean? In terms of toxicity, like HFCs, A2Ls have a permissible exposure limit of >400ppm and the related risk of accidents is low. In terms of an A2Ls flammability they typically require:
The effect of ignition from A2Ls is low (when compared to hydrocarbons) and they are difficult to ignite. It is necessary that components with ignition sources are avoided, and appropriate ventilation is provided where necessary as per guidance to relevant standards. E.g. BS EN378 In practical terms the quantity of an A2L would have to be greater than an A3 to create a flammable mix, as its flame when ignited travels at a slower rate. This has a positive impact on the maximum charge size of an A2L when compared to an A3 refrigerant. Will 2016 be the year of A2Ls?A2Ls will have a place in our industry, to what extent cannot be predicted. If you are considering an A2L it is essential that you consider the following:
An advantage of A2Ls opposed to other low GWP refrigerants such as CO² is that they operate very similarly to A1 HFC refrigerants. A2Ls may be more expensive, especially initially however this may be an acceptable trade-off when assessing their application against other alternative refrigerants Finally, there is certain to be all sorts of different information flying around over the coming months regarding A2L’s. Some of this information will be less accurate than others. If you are considering using A2L’s and wish to receive impartial advice from independent expert consultants, please do not hesitate to get in touch.
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The result of these changes is that while HFOs are stable in systems, they break down in the atmosphere over a few days: this is how they have global warming potential (GWP) ratings from 150 to less than 1. Additionally, HFOs are either A1 or A2L refrigerants, meaning they are either non-flammable or mildly flammable. HFOs, and blends including HFOs, are expected to be used in air-conditioning and refrigeration applications. Refrigerants classified as HFO currently on the market comprise: R1234yf, R1234ze and R1234zd. This website requires certain cookies to work and uses other cookies to help you have the best experience. By visiting this website, certain cookies have already been set, which you may delete and block. By closing this message or continuing to use our site, you agree to the use of cookies. Visit our updated privacy and cookie policy to learn more. This Website Uses Cookies By closing this message or continuing to use our site, you agree to our cookie policy. Learn More This website requires certain cookies to work and uses other cookies to help you have the best experience. By visiting this website, certain cookies have already been set, which you may delete and block. By closing this message or continuing to use our site, you agree to the use of cookies. Visit our updated privacy and cookie policy to learn more. |
Why are some HFO refrigerants classified as A2L
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