A pressure relief valve includes the following features. A housing defines an inlet and an outlet. The housing defines a flow passage between the inlet and the outlet. A seat can be defined by the housing. The seat defines a throat flow area. A plunger is configured to rest upon the seat. The plunger blocks the flow passage when in a closed position. The plunger is configured to actuate between a fully open position and the closed position. The plunger and the seat can at least partially defining a curtain flow area. A bias directs the plunger towards the seat. A ratio of the throat flow area to the curtain flow area is sized for sonic or supersonic flow velocities during critical flow conditions and subsonic velocities during subcritical flow conditions.

A pressure relief valve includes the following features. A housing defines an inlet and an outlet. The housing defines a flow passage between the inlet and the outlet. A seat can be defined by the housing. The seat defines a throat flow area. A plunger is configured to rest upon the seat. The plunger blocks the flow passage when in a closed position. The plunger is configured to actuate between a fully open position and the closed position. The plunger and the seat can at least partially defining a curtain flow area. A bias directs the plunger towards the seat. A ratio of the throat flow area to the curtain flow area is sized for sonic or supersonic flow velocities during critical flow conditions and subsonic velocities during subcritical flow conditions.

A pressure-maintaining valve for a reversible connection to an air line, having a basic body with an inlet opening, an outlet opening for accommodating the air line, and a fluid chamber which connects the inlet opening to the outlet opening in a fluid-communicating manner. A piston which is mounted movably between a sealing position, an equalizing position and a release position is arranged in the inlet opening, and the piston has an annular groove with a piston sealing surface and a piston release surface. In the sealing position, a sealant is arranged in a sealing manner between the piston sealing surface and a basic body sealing surface. In the equalizing position an equalizing line arranged in the sealing piston bypasses the sealant in a fluid-communicating manner. In the release position, the piston release surface lifts off the sealant from the basic body sealing surface.

A pressure-maintaining valve for a reversible connection to an air line, having a basic body with an inlet opening, an outlet opening for accommodating the air line, and a fluid chamber which connects the inlet opening to the outlet opening in a fluid-communicating manner. A piston which is mounted movably between a sealing position, an equalizing position and a release position is arranged in the inlet opening, and the piston has an annular groove with a piston sealing surface and a piston release surface. In the sealing position, a sealant is arranged in a sealing manner between the piston sealing surface and a basic body sealing surface. In the equalizing position an equalizing line arranged in the sealing piston bypasses the sealant in a fluid-communicating manner. In the release position, the piston release surface lifts off the sealant from the basic body sealing surface.

Embodiments of the invention provide for a system and method for operating a hydraulic tool near high-voltage components. The hydraulic tool may be connected to couplers and receiving hydraulic fluid from a pump and returning the hydraulic fluid to a tank in an open center system or returning the hydraulic fluid to a tank in a closed center system. In the event of a loss in pressure the valves in the system change state stopping the flow of hydraulic fluid to the hydraulic tool without the use of electrical components.

Embodiments of the invention provide for a system and method for operating a hydraulic tool near high-voltage components. The hydraulic tool may be connected to couplers and receiving hydraulic fluid from a pump and returning the hydraulic fluid to a tank in an open center system or returning the hydraulic fluid to a tank in a closed center system. In the event of a loss in pressure the valves in the system change state stopping the flow of hydraulic fluid to the hydraulic tool without the use of electrical components.

A pressure regulator device for use within a pressure-regulated fluid storage and dispensing vessel primarily in low flow, low delivery pressure applications. Regulator stiction challenges have been solved with an improved poppet assembly using different poppet element configurations as well as an improved bellows structure in the pressure-sensing assembly that provides more flexibility during contraction and expansion of the diaphragm elements.

A pressure regulator device for use within a pressure-regulated fluid storage and dispensing vessel primarily in low flow, low delivery pressure applications. Regulator stiction challenges have been solved with an improved poppet assembly using different poppet element configurations as well as an improved bellows structure in the pressure-sensing assembly that provides more flexibility during contraction and expansion of the diaphragm elements.

A gas regulator includes a valve chamber body that houses two valves of the regulator. Valve elements that move to open and close the two valves are received via a same opening into the valve chamber body, which is closed by a plug. The plug can define a first valve seat as well as a piercing element used to pierce a compressed gas cylinder. A retainer can hold a gasket at a valve seat as well as provide a bore or other support for a valve element and valve element spring.

A gas regulator includes a valve chamber body that houses two valves of the regulator. Valve elements that move to open and close the two valves are received via a same opening into the valve chamber body, which is closed by a plug. The plug can define a first valve seat as well as a piercing element used to pierce a compressed gas cylinder. A retainer can hold a gasket at a valve seat as well as provide a bore or other support for a valve element and valve element spring.