ANSI/ASHRAE Standard 158.2 provides methods of determining the mass flow capacity of refrigerant pressure regulators with sufficient accuracy to facilitate proper engineering application of the device in systems operating at various conditions with various refrigerants.

It prescribes a method of measuring key flow and gradient characteristics of refrigerant pressure regulators using air or water as the working fluid and prescribes computational means to enable reliable prediction of refrigerant.

The 2024 edition of Standard 158.2 makes minor editorial changes and further aligns the standard with ASHRAE policy regarding systems of units and mandatory language.