How the screw-in check valve works


Snap check valve is a valve that relies on the flow of the medium itself and automatically opens and closes the valve flap to prevent the backflow of the medium, also known as check valve, check valve, backflow valve and back pressure valve. The snap check valve is a kind of automatic valve, its main role is to prevent the backflow of media, prevent the pump and drive motor reversal, as well as the release of the container medium. The snap check valve can also be used to provide recharge to the auxiliary system in which the pressure may rise above the system pressure. Snap check valves can be mainly divided into swing type snap check valves (rotating according to the center of gravity) and lift type snap check valves (moving along the axis). The function of this type of valve is to allow the medium to flow in one direction only, and to prevent the flow in the opposite direction. Usually this valve is automatic work, in one direction of flow of fluid pressure, the valve flap open; fluid flow in the opposite direction, by the fluid pressure and the self-weight of the valve flap combined flap act on the valve seat, thus cutting off the flow.
Among them, snap check valve belongs to this type of valve, which includes swing type snap check valve and lift type snap check valve. Swing check valves have a hinge mechanism and a door-like flap that rests freely on an inclined seat surface. To ensure that the flap reaches the proper position on the seat surface every time, the valve is designed to be hinged so that the flap has sufficient swing space and true, full contact with the seat. The valve may be made entirely of metal, or may be inlaid with leather, rubber, or synthetic coverings, depending on the performance requirements. Swing-open snap check valves have virtually unobstructed fluid pressure in the fully open condition, so the pressure drop through the valve is relatively small. The flap of the lift-off snap check valve is located on the sealing surface of the seat on the valve body. This valve is like a globe valve except that the flap is free to lift and lower, and fluid pressure causes the flap to lift off the seat sealing surface, and media backflow causes the flap to fall back onto the seat and cut off the flow. Depending on the conditions of use, the flap can be of all-metal construction or in the form of a rubber gasket or rubber ring inlaid on the flap frame. Like the globe valve, the passage of fluid through the lift type snap check valve is narrow, so the pressure drop through the lift type snap check valve is somewhat greater than that of the swing type snap check valve, and the flow rate of the swing type snap check valve is very little restricted.