R1234yf
Also known as: HFO-1234yf, R-1234yf, Opteon YF, Solstice yf
Short definitionAn HFO gas that breaks down in the air within days and has a GWP of only 4. It has replaced R134a in car air conditioning; it is mildly flammable (A2L) and the main component of low-GWP blends.
A cold room owner does not see this gas on a cylinder but reads it in the composition line of the blend in use. More than half of R513A, over three quarters of R454C and between a fifth and a quarter of R448A and R449A is R1234yf; it is what pulls the blend’s greenhouse effect down. The double bond in its molecule breaks quickly in the atmosphere, so its lifetime is about 11 days. It contains no chlorine. Its pressures are very close to those of R134a and its capacity slightly lower.
On its own it is used in chillers, small plug-in cabinets and some heat pumps. It takes POE oil in stationary plant and PAG oil in car air conditioning. Being flammable, it cannot be transferred into an R134a unit; the equipment must be built for A2L. It costs many times more than R134a; every leak shows on the invoice. In a brazing flame it decomposes into toxic, corrosive gas. So the circuit is emptied first, nitrogen is passed through, and only then is it brazed. It is odourless; leaks are searched for with a detector.