| 摘要 |
A liquid pressure reducing regulator having a pressure receiving means in liquid communication with the liquid inlet passage, upon which a liquid in the liquid inlet passage can exert a balancing force, and a means for communicating the balancing force to the diaphragm opposing an overpressure force exerted by the inlet liquid on the pressure control diaphragm. The liquid pressure regulator typically employs a balancing piston that can transfer pressure fluctuations in the flow outlet into an equal and opposite force on the valve plug, and results in a net force of zero in the diaphragm plate. As a result, changes in the liquid pressure downstream of the valve plug only nominally, and typically negligibly, affect the upstream control of the liquid product. The invention also relates to a liquid pressure control valve having a liquid housing defining a liquid flow passage having a first flow passage, a second flow passage, and an orifice means intermediate between and providing communication between the first flow passage and the second flow passage, the orifice means having an opening, and a diaphragm assembly comprising a diaphragm having a liquid side forming a portion of the first flow passage, and an opposed control side, the diaphragm being moveable along a central axis. A control housing has a control means for applying a control force to the control side of the diaphragm. A valve plug is positioned proximate the opening of a valve orifice having a variable effective area as a function of the position of the valve plug. The valve plug has an opposed second side having a second surface in liquid communication with the second flow passage, where against a liquid in the second flow passage can exert a differential force against the diaphragm. The control valve has a pressure receiving means in liquid communication with the second flow passage, upon which a liquid in the second flow passage can exert a balancing force, and a means for communicating the balancing force to the diaphragm opposing the differential force.
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