R290 is high-purity propane, dried and cleaned for refrigeration use. It boils at about −42 °C at atmospheric pressure, so it suits both chillers and freezers. Its thermodynamic properties are excellent, so compressors designed for it often run more efficiently than equivalent ones on R134a or R404A, and only a small charge is needed.
It is flammable, classified A3 in refrigerant safety groupings. For that reason, cabinets are designed with a small sealed charge, spark-free electrical components near the refrigerant circuit, and markings that warn technicians. Safety standards for commercial appliances limit how much hydrocarbon a single circuit may contain. In normal use this is not a hazard; the risk is during careless repair, especially brazing on a system that has not been fully recovered and purged.
R290 is now the mainstream choice for plug-in reach-ins, visi coolers, display cases and many deep freezers in markets moving away from high-GWP gases. In India, service skills for hydrocarbons are growing, but buyers should still check that their technician is trained and uses proper tools.