Understanding safety, relief and safety relief valves

摘要

In order to protect equipment and personnel, a safety valve, pressure relief valve or safety relief valve should perform the following functions: * Open in the case of an improper increase in system pressure * Prevent a pressure rise higher than that for which it is designed * Reseat (close) after a pre-determined pressure drop * Provide leak-proof shut-off during normal system operating conditions. These valves can either be pilot operated or spring, weight or supplementary loaded. Semi or full nozzle designs further distinguish various types. In order to distinguish between the various types of pressure relieving valves, a few definitions should be understood.