Series LF40L, LF40XL Automatic Reseating Temperature and Pressure Relief Valves are used in commercial water heater applications to provide automatic temperature and pressure protection to hot water supply tanks and hot water heaters. They feature a Lead Free* brass body with NPT male inlet and NPT female outlet connections, unique thermostat with special thermo-bonded coating, tamper-resistant bonnet screws, automatic reseating feature, and test lever. Model LF40L has a short thermostat for installation directly in available tank tapings. Model LF40XL has an extension thermostat for installation in the hot water outlet within the allowable distance from the top of the tank. Series LF40L, LF40XL valves are ASME rated and CSA listed.