The UK company’s 3800L Series pilot operated pressure relief valves with modulating pilot controls (PCM) have been certified by the American Society of Mechanical Engineers to handle air, gas and vapour. Previously, the 3800L was only certified for liquids.
The addition of air, gas and vapour certification allows the 3800L to be ASME Code stamped for use in both compressible and non-compressible services. The company says that the availability of a pilot operated relief valve certified for both compressible and non-compressible services provides for an attractive option in applications that can experience two-phase flow.
Operators typically have to choose between using a liquid or vapour certified pressure relief valve that will generally only perform properly under one type of service fluid. The 3800L with PCM control id designed to give plant operators confidence that the relief valve will operate as intended during an overpressure situation in both compressible and non-compressible services.
When the 3800L is used for more than one fluid type or for two phase flow applications, the nameplate may be marked with both an air and liquid certified capacity and ASME Code Stamped. There is no change in the overall valve design or spring selection. Valve opening pressure remains within ASME Code tolerances regardless of the relieving fluid condition.