Abstract: A fluid actuated pilot assembly employing a cantilevered spring member which is mounted to apply a force to a sensing piston in opposition to the force applied by the sensed fluid pressure. Upon the occurrence of the pressure of the fluid being sensed exceeding the force of the cantilevered spring member, the sensing piston is moved to initiate a control function.

Abstract: An apparatus and method are provided in which the apparatus is insertable along a pressure transmission conduit extending from a source point to a pressure responsive device, such as a safety valve in a subterranean well. The apparatus has a fluid passageway through a housing with inlet and outlet means for communicating the passageway to the transmission conduit. A frictionless ball valve head and seat means are disposed in the housing and across the passageway for selectively isolating pressure communication between members of the transmission conduit. Means, such as a plunger, are provided for shifting the ball valve head off of its seat, with piston means being carried by the plunger and including a piston head which is responsive to differential pressure for urging the plunger in a first direction to move the ball valve to its seat upon increase of pressure in the conduit above a predetermined value.

Abstract: A bimodal, non-venting pneumatic relay senses the presence or absence of a first pressurized fluid and controls the supply or temination of a second pressurized fluid to associated equipment. The relay includes a segmented housing defining plural grooves which accept annular seals, a valve stem against which the seals seat and a reversible piston. The reversible piston can be selectively oriented and installed to provide either, manual rest operation to interrupt the supply of the second fluid if the first fluid supply is interrupted, the relay requiring manual resetting to reestablish supply of the second fluid, or automatic reset operation, wherein restoration of the second fluid supply is achieved automatically if the first fluid pressure is re-established subsequent to an interruption.