... -term substitute for R502, mainly used in refrigerating systems of low & moderate temperature...Physical Properties Quality Specification Molecular formula Purity, %≥99.8Boiling ... Temperature,°C72.1Acidity, ppm≤0.1Critical Pressure,Mpa3.74Evaporating Residue,ppm≤100ODP0AppearanceColourless,No turbidGWP0.83OdorNo strange stenchLiquid Density,g/cm31.05 r404a gas ...