ASHRAE has published ANSI/ASHRAE Standard 34-2001, Designation and Safety Classification of Refrigerants. The standard establishes a simple means of referring to common refrigerants in place of chemical names, formulas or trade names. It also establishes safety classifications based on toxicity and flammability data.
Standard 34-2001 incorporates the 1997 standard as well as 17 previously approved addenda. The standard is published on a three-year cycle to coincide with the deadlines for adoption by major building code organizations.