Cla-Val 55L-60 Pressure Relief Valve / Pump Casing Relief Valve is a direct-acting, spring-loaded, diaphragm-type relief valve. This pressure relief valve may be installed in any position and will open and close within very close pressure limits. The bottom plug may be removed and installed in the inlet to convert it to an angle pattern flow path. The Model 55L-60 is typically used in a fire protection system to trim water pressure, thus preventing pressure build-up whenever line pressure exceeds the setting of the spring. The 55L-60 relieves excess pressure to the atmosphere to prevent damage to the distribution network.