What are the key physical properties and applications of R22 (chlorodifluoromethane)?

What are the key physical properties and applications of R22 (chlorodifluoromethane)?
R22, chemically CHClF2, is a hydrochlorofluorocarbon with a molecular weight of 86.5 g/mol. Its standard boiling point is -40.82°C, critical temperature 96°C, and critical pressure 5 MPa. Liquid density is 1.177 g/cm³ at 20°C, with vapor density 4.82 times that of air. These properties make R22 efficient for medium and low-temperature refrigeration. Applications span residential and central air conditioning, heat pump water heaters, dehumidifiers, cold storage, marine refrigeration, industrial cooling, and supermarket display cases. Beyond cooling, R22 serves as a key feedstock for polytetrafluoroethylene (PTFE) resin production and as an intermediate for Halon 1211 fire extinguishing agents. It is also used as a physical blowing agent for polymer foams and as a propellant in aerosols for insecticides and paints. Despite its versatility, R22's ozone depletion potential drives its ongoing phase-down.