Abstract: A redundant sealing system with secondary containment for preventing leakage of fluid along a valve shaft is provided. The system comprises a first set of dynamic seals, a second set of dynamic seals, an auxiliary barrier fluid chamber, and a barrier fluid indicator. The first and second set of dynamic seals are in spaced relation to each other a distance equal to or further than a maximum stroke length of an actuatable valve stem. The auxiliary barrier fluid chamber is interposed between the first and second sets of dynamic seals. The barrier fluid indicator has a piston in a primary barrier fluid chamber. A first face of the piston is exposed to the auxiliary barrier fluid chamber. A second face of the piston is exposed to a barrier fluid and inhibited from fluid communication with the auxiliary barrier fluid chamber by a dynamic seal in the first set of dynamic seals.

Abstract: A valve assembly is disclosed that provides for complete or partial fluid pressure balancing across the valve, and can be used for reducing valve actuation forces in order to employ electric actuation. The valve assembly includes a valve housing having a valve chamber, a flow passageway, and a piston chamber. A valve member is disposed in the valve housing and is movable along a valve axis. The valve member is subjected to a first pressure, which urges the valve in a first direction. To counteract this force, a piston integral with the valve member is slidably arranged in the piston chamber. One side of the piston is subjected to this first pressure to provide a counterbalancing force. A pressure passage fluid communication of the first pressure between the flow passageway and said one side of the piston.

Abstract: A high recovery sonic gas valve design with the inlet flow entering transverse and orthogonal to the outlet flow is presented. The configuration cancels the effects of the inlet flow entering orthogonal to the axis of the nozzle and diffuser. The inlet passage is curved in a manner to let the flow enter along the centerline of the nozzle and diffuser. The nozzle is contoured and provides upstream flow impedance. The diffuser is contoured with the area gradient varying from a low positive value at the nozzle throat then to a maximum value and finally dropping off significantly to near zero prior to the nozzle exit. The diffuser is nearly cylindrical and may extend past the valve outlet flange and protrude into adjacent piping.