ASHRAE Standard 15 establishes safeguards for life, limb, health, and property and prescribes safety requirements. This standard is directed toward the safety of persons and property on or near the premises where refrigeration facilities are located. It includes specifications for fabrication of tight systems but does not address the effects of refrigerant emissions on the environment. This standard applies to (a) the design, construction, test, installation, operation, and inspection of mechanical and absorption refrigeration systems, including heat pump systems used in stationary applications; (b) modifications including replacement of parts or components if they are not identical in function and capacity; and (c) substitutions of refrigerant having a different designation.

The 2019 edition of Standard 15 incorporates the following changes:

• Makes changes to requirements for R-717 ammonia systems
• Introduces requirements specific to Low Global Warming Potential (Low GWP) A2L refrigerants
• Changes restrictions for small, self-contained systems with higher-flammability refrigerants
• Defines “low-probability pumps” and provides requirements for their use
• Identifies requirements when changing a refrigerant within the same refrigerant class and lists restrictions on mixing refrigerants from different classes

ASHRAE Standard 34 is intended to establish a simple means of referring to common refrigerants instead of using the chemical name, formula, or trade name. It establishes a uniform system for assigning reference numbers, safety classifications, and refrigerant concentration limits to refrigerants. The standard also identifies requirements to apply for designations and safety classifications for refrigerants and to determine refrigerant concentration limits. This standard provides an unambiguous system for numbering refrigerants and assigning composition-designating prefixes for refrigerants. Safety classifications based on toxicity and flammability data are included along with refrigerant concentration limits for the refrigerants. This standard does not imply endorsement or concurrence that individual refrigerant blends are suitable for any particular application.

The 2019 edition of Standard 34 incorporates the following changes:

• Addition of fifteen total new refrigerants
• Revisions to make 2L a separate flammability classification of refrigerants
• Changes that base toxicity classification on the nominal formulation of the blend
• Corrections to language for the proper naming of molecules containing iodine
• Revisions to address fluids whose critical temperature is lower than 130°F (54.4°C)
• Standardization of terminology