| 摘要 |
A process control valve is disclosed including a valve body assembly which includes process fluid input and output ports, an actuation pressure port and a vent port. The valve body includes a cylinder with two pistons longitudinally spaced and separated by a biasing means such as a spring. The pistons each have a rod which acts as a seal for a process fluid port when normally biased by the biasing spring. The actuation port of the body assembly communicates with the opposite faces of the pistons from the bias spring to open the process fluid input and output ports by overcoming the biasing port closing force. The two pistons include rods having process fluid passageways therethrough. The pistons also include a valve poppet & seat combination which is closed whenever actuation force is applied to the process control valve sealing the process fluid path from the vent port. A reversible input/output valve is disclosed as well as a modular assembly of interchangeable valves is disclosed.
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