In our latest blog we look at pilot check valves and how they play a leading role in controlling a hydraulic system’s direction of flow. Operating in a similar fashion to a standard check valve, a pilot check valve enables flow in a reverse direction by holding the valve open. They are unique in the fact that they can stop the fluid flow going in one direction by holding it, only to be released when the correct level of pilot pressure is supplied. So without the necessary pressure, the small spring-loaded poppet or equivalent which is situated in the pilot valve will move into place to close the gap, thus stopping the flow. A pilot valve’s fluid control explained In order to push the flow in a forward direction, the pilot line pressure holds the valve open ready for fluid heading in the reverse direction when required. With a pressurised pilot line, fluid flow will go back into the reservoir from the press cylinder as the valve has been held open. A specific amount of pilot pressure is then required to open the check valve. It is recommended to have as small amount of pressure as possible to keep the valve open. There are two common types of pilot operated check valves and these are the threaded cartridge variety and the pilot piston style. These designs have proven to be the most reliable and efficient in testing and are popular choices for the majority of users as they work well with control valves as once they have been centred, they allow the valve ports to efficiently vent back to the tank. Pilot check valves also have excellent sealing quality when the valve is closed to help eliminate leakage and cylinder creep. They are designed to work to fluid pressures over 20,000 psi and come in a range of popular fitments, typically 1/8” through to 1/2“ and constructed from stainless steel. At Hydraproducts, we have available in stock our popular Z2DS series pilot operated check valve which is designed to allow leak free closing of both A & B service ports. Operating to pressures up to 315bar and pilot ratios of 3:1, our CE Approved units are the ideal solution for your fluid flow needs. Please visit our new Components Division site online now to view our full range of hydraulic valves and other hydraulic system parts.