Vented pilot to open check valve

The valve is a pilot to open check valve, which may be opened to permit flow in the reverse direction. It allows free flow from port A to B, if the differential pressure exceeds the opening pressure and blocks flow in the opposite direction. Pressure at the pilot port X will open the valve from port B to port A. Pilot pressure needed to open the valve is directly proportional to the load pressure at port B. The valve is insensitive to pressure at port A, because the spring chamber is connected with the vent port Y.

The area ratio relates to the working area ratio X : B.

If the ports X and Y are not under pressure, the valve starts to open, when pA - pB > p0.

The pressure regulation range dp is the pressure increment above the opening pressure, at which the valve is fully open.

The valve is fully open, when pA – pB > p0 + dp.

The hydraulic resistance relates to the fully open valve.