Introduction of Relief Valves
Relief valves are found in many pressurized systems that involve the control of fluid flow, such as ones that are controlled electronically, hydraulically, or pneumatically. While typical systems such as these require some source of power to operate them, relief valves must by their nature be capable of operating under all conditions, especially in the case of failure of primary power when the system controls may not be operable. For this reason, relief valves are primarily not separately powered devices and use the passive power of the process fluid pressure to actuate the valve. Components and Operation of Conventional Relief Valves The valve inlet nozzle which is connected to the system or pressure vessel for which protection is being provided. A moveable disc or diaphragm that controls the flow of fluid through the valve and to the outlet port. A spring that seats the disc in place to keep the valve closed and that allows the valve to open when the system pressure exceeds a pre-d