The Cla-Val Model 55L (UL listed, FM approved) Pressure Relief Valve is a direct-acting, spring-loaded, diaphragm type relief valve. The valve may be installed in any position and will open and close within very close pressure limits. Using the Model 55L in a fire protection system or other closed type systems, prevents pressure build-up whenever line pressure exceeds the setting of the spring. The valve will relieve excess pressure to the atmosphere preventing damage to the distribution network.