States that the results of ASHRAE Research Project 601 have shown that the contaminant levels of used CFC and HCFC refrigerants exceed the contaminant levels of fresh refrigerants, regardless of the service required by the air conditioning or refrigerating system. The types and concentrations of the contaminants and consequently the potential for successful recycling are dependent on the type of refrigerant (R11, R12, R22 or R502) and the type of service (normal or burnout) required by the system. Reports results of a laboratory recycling study which showed that an alumina/molecular sieve dryer was very effective in removing acids from used refrigerants and had insignificant effects on the volatile impurities and high boiling residue. The recycling study also indicated that the capability of the dryer to remove water from the used refrigerants would be improved if the oil and acids were separated from the refrigerant prior to water removal.

KEYWORDS: Refrigerants, contaminants, fluorocarbons, refrigeration, R11, R12, R22, R502, recycling