The center vertical pin shaft. When the valve is open, the resultant force of fluids is on the center of sealing face of the disc, while the point of action of counter spring support force is on the center of disc surface so that the root of the disc opens firstly. It avoids wearing of the sealing surface of the old conventional valve when the valve opens, and increases the persistence of valve seal.

When the flow slows down, the counter force of the torsion spring makes the disc moves to the valve seat, and the valve is in slow off stage. When fluid flow backwards, the closing speed of the disc is correspondingly increased and it enters the rapid closing stage under the force of backflow fluids on the disc and counterforce of the torsion spring. The influence and harm of water hammer is effectively reduced. When closed, the spring force closes the top of the disc firstly so that the root of the disc is prevented from being bitten to guarantee longer service life of valve sealing surfaces.

The API 594 single disc wafer check valve is a single disc swing wafer connecting check valve that prevents backflow of the medium. They are all ultra-thin check valves. The single disc swing wafer connecting check valve is designed to be connected through the wafer. Stainless steel or stellite build-up welding may be applied to sealing surfaces of the valve body and the disc. The valve is suitable for the clean medium, and not suitable for medium with solid particles and great viscosity. The main merit of the tilting disc check valve is that it overcomes shock and water hammer in operating condition of swing check valves and lifting check valves to realize shock-free operation.