Abstract: A three position, high and low, block and bleed fluid pressure sensor, wherein a piston contained within a cylinder is urged in one direction by a fluctuating sensed fluid pressure and opposed by a single spring located within said cylinder housing. The cylinder housing includes inlet and outlet ports, and at least one venting port. When the equilibrium of the forces between the spring and the fluid port pressure places the piston in a first position, the inlet and outlet port are allowed to communicate by way of an internal passageway formed within the piston and the sensed fluid may pass therethrough. When the pressure exerted by the fluctuating port pressure is greater or lower than the desired range, the piston will assume a second or third position wherein the inlet and outlet ports are misaligned whereby the inlet port is blocked and the outlet port merely discharges residual fluid through one of the venting ports.

Abstract: A pilot valve is disclosed having a piston actuating a valve element shiftable between a first and second positions. The piston is comprised of two concentrically arranged pistons, the larger piston having an internal bore with two sections of staggered diameters and a smaller, correspondingly shaped second piston inserted in the concentric internal bore. A single O-ring on the bottom of the second section of the first piston annularly mounted around the second section of the second piston seals the piston chamber from a fluctuating sensed fluid pressure. The first piston has a longer upper bore section than the second piston. A spacer is placed at the juncture of the first and second sections of second piston so as to enable the first and second piston to act in unison in actuating the valve element. In this mode, the effective surface area of the piston is equal to the diameter of the larger piston or of the O-ring.

Abstract: A housing/piston mechanism for sensing a control fluid pressure and shifting a valve element in response thereto. The piston mechanism comprises a first piston having an internal bore in which is positioned a second piston, and a third piston for use in one specific orientation within the piston housing. Varying ranges of fluid pressure sufficient to actuate the piston mechanism are accomplished by positioning the piston mechanism within its piston chamber in varying orientations so that the effective piston surface area exposed to a control fluid is dictated by the specific orientation of the piston mechanism within the chamber. In one orientation, the effective fluid pressure surface area is that of the larger piston member. In a second orientation, the effective surface area exposed to the sensing fluid is a first surface of the smaller piston carried by the larger piston. In a third orientation, the effective surface area exposed to the sensing fluid is that of the opposite end of the second piston.

Abstract: A piston mechanism for sensing a control fluid pressure and shifting a valve element in response thereto. The piston mechanism comprises a first piston having an internal bore in which is positioned a second piston. Varying ranges of fluid pressure sufficient to actuate the piston mechanism are accomplished by positioning the piston mechanism within its piston chamber in varying orientations so that the effective piston surface area exposed to a control fluid is dictated by the specific orientation of the piston mechanism within the chamber. In one orientation, the effective fluid pressure surface area is that of the larger piston member. In a second orientation, the effective surface area exposed to the sensing fluid is a first surface of the smaller piston carried by the larger piston. In a third orientation, the effective surface area exposed to the sensing fluid is that of the opposite end of the second piston.

Abstract: A valve assembly comprises a valve body having a hollow and a valve element longitudinally movable between first and second positions therein. The valve assembly has at least one inlet and at least one outlet in pressure communicating relation to the hollow. The valve element in its first position blocks pressure communication between the inlet and the outlet. In its second position, the valve element permits pressure communication between the inlet and the outlet. A pressure sensitive indicator is operatively associated with the valve element. The assembly provides pressure communication between the inlet and the indicator when the valve element is in one of its positions and blocks such pressure communication in the other position. The assembly may also include other inlets and outlets, and the high pressure inlets are preferably longer than the respective controlling seals. Thus the seals need not cross the inlets to control flow therethrough.

Abstract: A pneumatic relay valve is actuated by a pressure differential determined by the respective surface areas of two opposing surfaces of a piston moveable within the valve body. A first pressure (pilot signal) to be monitored maintains the piston member of the valve in its "in-service" position, blocking all ports in the valve body. Upon the occurrence of a sufficient pilot signal pressure drop, a second continuous common supply pressure moves the piston to a "tripped" position, sealing off the pilot signal inlet port to enable the second (common supply) pressure to bleed to the atmosphere. This sudden loss of common supply pressure causes a common supply relay valve to "trip," closing off all common supply fluid pressures to each of a plurality of first relay valves. Only upon reinstatement of the first interrupted pilot signal pressure may the relay valve be manually reset to the "in-service" position and maintained in that position by sufficient pilot signal pressure.

Abstract: A valve assembly comprises a valve body having a hollow and a valve element longitudinally movable between first and second positions therein. The valve assembly has at least one inlet and at least one outlet in pressure communicating relation to the hollow. The valve element in its first position blocks pressure communication between the inlet and the outlet. In its second position, the valve element permits pressure communication between the inlet and the outlet. A pressure sensitive indicator is operatively associated with the valve element. The assembly provides pressure communication between the inlet and the indicator when the valve element is in one of its positions and blocks such pressure communication in the other position. The assembly may also include other inlets and outlets, and the high pressure inlets are preferably longer than the respective controlling seals. Thus the seals need not cross the inlets to control flow therethrough.

Abstract: A check valve is disclosed which uses a valve body having a bore with a first section smaller than a second section, an inlet communicating with the first section to receive flowing fluid, a shoulder disposed between the first section and the inlet for providing a valve seat, and an outlet communicating with the second section for discharging the fluid. A valve element is mounted within the inlet for engaging with the valve seat to shut off the fluid flow. A movable piston is mounted with the valve body to control movement of the valve element. The piston has a body portion slidably mounted with the second section, the body portion having a shoulder facing away from the valve element; a male portion is slidably mounted with the first section and extends from the body portion, the male portion having a shoulder facing toward the valve element; and a stem extends from the male portion into the inlet of the valve body for mounting with the valve element.

Abstract: A valve assembly comprises a valve body having a bore therein, a first opening communicating with the bore, and a second opening displaced from the first opening and also communicating with the bore. A valve element is slidably mounted in the bore for longitudinal movement therein between first and second positions. In the first position the first opening is sealed from communication with the second opening, and in the second position communication between the first and second openings is permitted via the bore. The valve element includes a pressure reaction area exposed to fluid pressure from the second opening in the second position whereby the valve element is retained in the second position upon the presence of fluid pressure in the second opening in excess of a given limit. The assembly further comprises return means for automatically returning the valve element to the first position upon the absence of fluid pressure above the limit in the second opening.