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Support
Hazardous plastic-based substances found in domestic refrigerators and air conditioners are as follows ;
• Polystyrene ( PS )
• Polypropylene ( PP )
• Acrylonitrile butadiene styrene ( ABS )
• Polyethylene terephthalate ( PET )
• High density polyethylene ( PE-HD )
• Low density polyethylene ( PE-LD )
Looking at the composition of fridges and unitary air conditioning systems we find that small fridges are predominantly composed of ferrous , non-ferrous metals ( brass , copper , aluminium , etc ) and plastics . Combined this account for 80 % of the weight of the refrigerator .
Air conditioners are similar but the compressor accounts for a large percentage of the weight of the unit . The air conditioner uses no foam insulation or glass . At this time most of the metal would be recovered and recycled but of course many other environmental pollutants remain . 1 . The compressor would normally be the heaviest part of the extracted components usually consisting of the following composition : 8 % copper , 57 % iron and 35 % cast alloy . Steel is found on the external casing of refrigerators and air conditioners as well as in the shelving in refrigerators . The condensing units of air conditioners contain copper-aluminium coils whereas the domestic fridges are made of steel . Commercial fridges contain copper-aluminium coils .
2 . The insulating foams are either PUR foam or glass wool and extruded polystyrene . The older type refrigerators used PUR foams containing CFC-11 and HCFC-141b as blowing agents . Most fridges contain 4-10kg of insulating polyurethane foam which in turn holds about 5-10 % of blowing agents by weight but generally more so in the lower percentage . There has been a switch to the use of cyclopentane as a blowing agent . Note : a pentane-air mixture can create an explosive atmosphere under certain conditions which must be kept in mind when dealing with the foam . In commercial units we find a wide diversity of insulation materials from typical PUR foam , foamed polystyrene ( styrofoam ) and mineral wool . Foamed polystyrene does not contain environmentally harmful blowing agents , so it doesn ’ t need special treatment . However , the mineral wool is more critical as it has carcinogenic properties .
3 . Moving on to plastics , a typical unit may contain 5-10 kg of plastics : mainly PS ( polystyrene ), PP ( polypropylene ),
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RACA Journal I November 2024 www . refrigerationandaircon . co . za