Balanced-piston valve
In automated control-valve applications, large, expensive, and cumbersome actuators (solenoids, motors, or cylinders) often dwarf the actual valves that they control. By splitting the upstream pressure, the BP valve conquers an old problem: the need for large operating forces. Instead, counterbalanced pistons, linked to a common shaft, roll open with relative ease, reducing valve size, mass, and power requirements.
Three components at the heart of the concept include a reciprocating cylindrical seat, a reciprocating solid plug, and a fixed-axis rotary shaft. A seated plug presents a solid face to block flow. When unseated, fluid flows around the plug and through the seat cylinder. Although fluid pressure pushes these two elements in a downstream direction, rotary-shaft linkage prevents movement. Because the pressure-induced forces on the seat and plug act on the shaft in opposite directions, they balance each other. Consequently, a slight torque applied to the shaft moves the plug and seat cylinder in opposite directions to each other, even with very high upstream pressures.
Rob Jaeger, NewValve.com, 3822 Cloverhill Ct., Brandon, FL 33511-7967; Tel. & Fax: (813) 654-4527; E-mail: Rob@NewValve.com.
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