Establishes a method of testing desiccants for use in refrigerant drying. Provides a method of testing desiccants only. For testing and rating driers that use these desiccants, refer to ANSI/ASHRAE Standard 63.1, Method of Testing Liquid Line Refrigerant Driers (see Informative Annex A--Bibliography). Principle of this standard is to keep a desiccant of known water content in contact with the desired refrigerant until equilibrium has been established under known temperature conditions, after which the water content of the refrigerant is determined. This standard is applicable to all desiccants that do not react with the desired refrigerant. Dual units of measurement.