Heat pump the brand name Freon, a trademark of DuPont. Its manufacture is now banned or severely restricted by the Montreal Protocol of August 1987 because of the damage that CFCs cause to the ozone layer if released into the atmosphere. One widely adopted replacement refrigerant is the hydrofluorocarbon (HFC) known as R-134a (1,1,1,2-tetrafluoroethane). Heat pumps using R-134a replaced R-12 (dichlorodifluoromethane) and have similar thermodynamic properties but with insignificant ozone depletion potential and a somewhat lower global warming potential. Other substances such as liquid R-717 ammonia are widely used in large-scale systems, or occasionally the less corrosive but more flammable propane or
Montreal Protocol their HFC use by 85 per cent of their average value in 2020-22 by the year 2045. India and some other developing countries — Iran, Iraq, Pakistan, and some oil economies like Saudi Arabia and Kuwait — will cut down their HFCs by 85 per cent of their values in 2024-26 by the year 2047. On 17 November 2017, ahead of the 29th Meeting of the Parties of the Montreal Protocol, Sweden became the 20th Party to ratify the Kigali Amendment, pushing the Amendment over its ratification threshold ensuring that the Amendment will enter into force 1 January 2019. In