Please note: All interim revisions for this edition available at time of your purchase will be included.Standard for Fire Pump Relief ValvesUL 1478Scope1.1 These requirements cover direct acting (spring loaded) and pilot operated fire pump relief valves of nominal 3/4 inch (19.05 mm) size and larger, intended for use in water supply systems for fire protection service.1.2 Requirements for the installation and use of these valves are included in the Standard for the Installation of Centrifugal Fire Pumps, NFPA 20.