Standard 158.2-2011 is a revision of Standard 158.2-2006 and provides methods of determining the mass flow capacity of refrigerant pressure regulators.

This standard 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 by a) prescribing a method of measuring key flow and gradient characteristics of refrigerant pressure regulators using air or water as the working fluid and b) prescribing computational means to enable reliable prediction of refrigerant vapor and liquid mass flow capacity based on the measured flow and gradient characteristics.

This standard applies to refrigerant pressure regulators that are intended for refrigerant service in applications where only single-phase flow occurs within the regulator. This standard is applicable to refrigerant pressure regulators in the following circumstances: a) for use in either liquid or vapor refrigerant applications and b) for use with refrigerants deemed suitable according to ANSI/ASHRAE Standard 15.

This standard does not do the following:
a. specify rating conditions or electrical or mechanical design requirements (rating conditions may be found in AHRI Standard 770),
b. make recommendations for safety, or
c. specify tests for production, specification compliance, or field testing of regulators