A check valve comprises a housing, a fluid passage, a seat, a valve member and a stop. The fluid passage extends through the housing. The seat is disposed in the fluid passage. The valve member is positioned in the passage to engage the seat. The stop extends through the housing to engage the valve member. The stop is accessible from outside the housing to adjust a distance the valve member can travel from the seat. In one embodiment, the stop includes a variable stop feature, such as an offset pin or a cam. In another embodiment, the stop includes a pump control valve. In yet another embodiment, the housing includes markings to indicate a position of the stop. The valve member comprises a ball or a poppet in different embodiments.

A check valve comprises a housing, a fluid passage, a seat, a valve member and a stop. The fluid passage extends through the housing. The seat is disposed in the fluid passage. The valve member is positioned in the passage to engage the seat. The stop extends through the housing to engage the valve member. The stop is accessible from outside the housing to adjust a distance the valve member can travel from the seat. In one embodiment, the stop includes a variable stop feature, such as an offset pin or a cam. In another embodiment, the stop includes a pump control valve. In yet another embodiment, the housing includes markings to indicate a position of the stop. The valve member comprises a ball or a poppet in different embodiments.

A vacuum valve is provided with opening pressure setting means that sets a set value of a fluid pressure in a primary side passage beyond which communication is opened and forcible opening means that forcibly opens communication regardless of the fluid pressure in the primary side passage. The opening pressure setting means includes a spring receiver fixed to a stem, a compression coil spring having a lower end supported by the spring receiver, and an adjustment screw, movable in the axial direction, that presses the upper end of the compression coil spring. The forcible opening means includes a piston inserted onto the stem 5 under the spring receiver so as to be movable upward and downward and piston driving means that moves the piston and the spring receiver upward integrally by moving the piston upward using compressed air.

A check valve comprises a housing, a fluid passage, a seat, a valve member and a stop. The fluid passage extends through the housing. The seat is disposed in the fluid passage. The valve member is positioned in the passage to engage the seat. The stop extends through the housing to engage the valve member. The stop is accessible from outside the housing to adjust a distance the valve member can travel from the seat. In one embodiment, the stop includes a variable stop feature, such as an offset pin or a cam. In another embodiment, the stop includes a pump control valve. In yet another embodiment, the housing includes markings to indicate a position of the stop. The valve member comprises a ball or a poppet in different embodiments.

A pressure regulating valve includes a housing defining a fluid passage between at least one inlet and one outlet. A ball valve is positioned within the fluid passage and biased by a spring. A cam is in biased engagement with the spring and ball valve to regulate pressure of fluid passing through the fluid passage. The cam includes multiple faces, each face milled to a different depth, and means for adjusting a position of the cam relative to the ball valve, such that a different face of the cam enters into biased engagement with the spring of the ball valve, thereby altering a compression force exerted by the spring on the ball valve. The faces of the cam correspond to increments of desired pressure adjustment, such that rotation or movement of the cam surface between different faces results in discrete changes to the pressure of fluid passing through the valve.