On refrigerants used for air conditioning. The last decade has seen radical changes in the selection and use of
refrigerants, mainly in response to the environmental issues of ‘holes in the ozone layer’ and ‘global warming or greenhouse effect’. Previously there had not been much discussion about the choice of refrigerant, as the majority of applications could be met by the well known and well-tested fluids, R11, R12, R22, R502 and ammonia (R717).  The only one of these fluids to be considered environmentally friendly today is ammonia, but it is not readily suited to commercial or air-conditioning refrigeration applications because of its toxicity, flammability and attack by copper. This site will be about the old and new refrigerants and the attitudes needed in design, maintenance and servicing of air conditioning equipment.