Permeation of Refrigerants Through Elastomeric and Plastic Hoses

High permeation losses through nitrile rubber hoses have prevented use of refrigerants other than R-12 in automobile air conditioners. Alternate hose materials were evaluated. Two materials were shown to have acceptable permeation loss rates of the two commercial refrigerants which appear suitable for automotive air conditioning. The effect of oil on refrigerant permeation was found to be relatively unimportant. Since two of the refrigerant candidates were azeotropes, R-500 and R-502, the effect of different permeation rates on the mixture composition was studied. Using permeation constants developed in this study, calculations were made of losses from a typical system which showed that permeation losses were small compared to other source losses, such as through fittings or shaft seals.