1 Scope

1.1 These requirements cover pressure relief valves intended for use in sprinkler systems for fire protection service to relieve excessive pressures in valve trim, downstream of a pressure reducing valve or caused by thermal expansion with a sprinkler system. These valves may also be suitable for use as a circulation relief valve for a fire pump based its relief valve pressure setting and inlet size.

1.2 Requirements for installation of these valves are included in the Standard for the Installation of Sprinkler Systems, NFPA 13 and the Installation of Stationary Fire Pumps, NFPA 20, as applicable.

Summary of Topics

This new Second Edition of ANSI/UL 1478A dated June 9, 2025 includes the following changes in requirements:

– Updating Scope of the Standard; 1.1 and 1.2

– Adjustable Pressure Relief Valves; 7.2, Section 17, 19.1, and 19.3

– Updating Format and Testing Details; Section 2, 3.1, Section 4, 6.1, Section 8 (title only), 10.1, 10.2, 12.1, Table 15.1, Section 16, 18.1, 19.1, and 19.2