R507A
Also known as: R-507A, AZ-50, R507
Short definitionA blend of R125 and R143a in equal weight; an azeotropic HFC with no glide. It does the same job as R404A in frozen applications and is banned in new systems because its GWP is 3,985.
It came out as a replacement for R502 and has been used in frozen storage rooms, blast freezing tunnels, ice machines and industrial low-temperature plants. It is class A1, runs on POE oil and boils at −47 °C at atmospheric pressure. Because it evaporates at a single temperature, it was preferred in plants with pumped and flooded evaporators; zeotropic blends can separate into their components there. Its pressure and capacity are 2–3 per cent above R404A.
In a project today you meet R507A only as the gas of an existing plant. It has been banned in new commercial systems since 2020; above a charge of 40 tonnes CO₂ equivalent, roughly 10 kg, service with virgin gas is restricted too. Direct expansion plants can move to R448A or R449A with the same compressor and oil. In flooded and pumped plants, conversion is studied project by project. Check the compressor manufacturer’s list of approved gases first.