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Engineered Control Valves, Safety Devices & Process Instrumentation
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Press Releases
Pilot Operated Relief Valves
![]() Diagram above illustrates seat tightness of a traditional spring loaded relief valve versus a pilot valve illustrating how much closer to set point a pilot valve can operate. Pilot valves operate on a very simple set up. A sensing line, usually connected into the inlet piping, is connected into the pilot control. Another line is piped from the pilot control into the top of the main valve assembly. The pilot, which contains a small spring assembly, is set at a certain set pressure. During normal operation the inlet pressure passes through the sensing line through the pilot and continues into the dome of the main valve. The inlet pressure in effect is placing pressure onto the piston inside the main valve to keep the valve closed. At set point the spring inside the pilot causes a small piston to slide down allowing the inlet pressure sitting on top of the main valve piston to relieve through the pilot’s exhaust. This causes the
main inlet pressure to be relieved through the main valve. The diagrams below illustrate this principle. Have a look at the following diagram which illustrates how pop action pilots open the main valve fully at set point whilst modulating pilots open the main valve according to relief demand.
Apart from these operational advantages there are many physical advantages of using a pilot valve: • More compact compared to conventional spring loaded relief valves. • Weigh less than conventional spring loaded relief valves for comparable valve sizes. These two points are clearly summarized in the following diagrams. • Backflow preventers. • Remote sensing. • Dual pilots. • Dirty service options. Consolidated is the only relief valve manufacturer that offers the ability to retrofit an existing spring loaded relief valve into a pilot valve. Any 1900 series Consolidated spring loaded relief valve can be converted into a 2900 series pilot valve that will give you all of the benefits a pilot valve can offer. |
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