This standard specifies the terms and definitions, classification and basic parameters, technical requirements, test methods, inspection rules and signs, packaging and storage of screw refrigeration compressors and screw refrigeration compressor units. This standard applies to screw refrigeration compressors (hereinafter referred to as compressors) and screw refrigeration compressor units (hereinafter referred to as “units”) that use R717, R22, R134a, R404A, R407C, R410A, and R507A as refrigerants. Compressors and compressor units using other refrigerants (such as R290, R1270, etc.) can be implemented as a reference. This standard does not apply to single-unit two-stage screw refrigeration compressors and their screw refrigeration compressor units.