R32 is pure difluoromethane; since it is not a blend it has no glide. For years it was used as a component of blends such as R410A, R407C, R448A and R449A, and after the 2010s it became an air conditioning refrigerant in its own right. The reason is simple: at 675 its GWP is a third of that of R410A (2,088), its heat-carrying capacity is high, and for the same capacity a charge 20–30% smaller than with R410A is enough. It boils at −52 °C at atmospheric pressure. It has no effect on the ozone layer; its ODP is zero.
Its pressures are close to those of R410A, a little above them: about 7.1 bar g at 0 °C and around 27 bar g at 45 °C condensing. For this reason it is used only with compressors, pipes and fittings approved for R32; it is not charged into R410A equipment. Its efficiency is a few points better than that of R410A. Its weak point is the discharge temperature: it comes out 10–20 K higher than with R410A, so at low evaporating temperatures compressors with liquid or vapour injection are needed.
Its safety class is A2L: it is not toxic but it is mildly flammable. It is hard to ignite and its flame spreads slowly; even so, it can ignite when it accumulates in an enclosed space. The EN 378 standard sets the maximum allowable charge according to the room volume and the installation height of the unit. In service a spark-free, A2L-approved recovery unit and vacuum pump are used, the area is ventilated, and before brazing the circuit is emptied and purged with nitrogen. This work should be done by technicians trained in flammable refrigerants.
In industrial refrigeration R32 is seldom seen on its own; its place is air conditioning, heat pumps and chillers. In cold room systems, however, you meet it inside blends: about a quarter of R449A and a fifth of R454C is R32, and it is the component that raises the capacity of these blends. The great majority of new split air conditioners sold in Turkey use R32. You can compare its saturation pressures side by side with R410A in our refrigerant pressure–temperature chart. When measuring, make sure the gauge is suitable for the R32 pressure range.