Refrigerants

  

Refrigerants
   A modern R-134a refrigeration compressor

     "Freon" is a trade name for a family of haloalkane refrigerants manufactured by Dupont and other companies. These refrigerants were commonly used due to their superior stability and safety properties. However , these  chlorine-bearing refrigerants reach the upper atmosphere when they escape. Once the refrigerant reaches the stratosphere , UV radiation from the sun cleaves the chlorine-Carbon bond , Yielding a chlorine radical. These chlorine atoms catalyze the breakdown of ozone into diatomic oxygen , depleting the ozone layer that shields the Earth's surface from strong UV radiation. Each chlorine radical remains active as a catalyst unless it binds with another chlorine radical , forming a stable molecule and breaking the chain reaction. The use of CFC as a refrigerant was once common , being used in the refrigerants R-11 and R-12. In most countries the manufacture and use of CFCs has been banned or severely restricted due to concerns about ozone depletion. In light of these environmental concerns , beginning on November 14 , 1994 , the Environmental Protection Agency has restricted the sale , possession and use of refrigerant to only licensed technicians , per rules 608 and 609 of the EPA rules and regulations; failure to comply may result in criminal and civil sanctions. Newer and more environmentally-safe refrigerants such as HCFCs (R-22,  used in most homes today) and HFCs (R-134a , used in most cars) have replaced most CFC use. HCFCs in turn are being phased out under the Montreal protocol and replaced by  hydrofluorocarbons (HFCs) such as R-410A , which lack chlorine. Carbon dioxide (R-744) is being rapidly adopted as a refrigerant in Europe and Japan. R-744 is an effective refrigerant with a global warming potential of 1. It must use higher compression to produce an equivalent cooling effect.