Flanged check valve refers to the valve that automatically opens and closes the disc depending on the flow of the medium itself to prevent the back flow of the medium, also known as the check valve, check valve, counter flow valve, and back pressure valve. Check valve is a kind of automatic valve, its main function is to prevent the back flow of the medium, prevent the pump and the drive motor from reversing, and the discharge of the container medium. Check valves can also be used to feed lines in which the pressure may rise to exceed the system pressure. Check valves can be mainly divided into swing check valves (rotating according to the center of gravity) and lift check valves (moving along the axis).

The purpose of this type of valve is to allow the medium to flow in only one direction, and to prevent the direction of flow. Usually the valve works automatically. The disc opens under the pressure of a fluid flowing in one direction. When the fluid flows in the opposite direction, the pressure of the fluid and the self-overlapping disc act on the seat to cut off the flow.

The flange type check valve belongs to this type of valve, which includes swing check valve and lift check valve. Swing check valves have a hinged mechanism and a door-like disc that rests freely against the sloped seat surface. To ensure that the disc reaches the seat surface each time, the disc is hinged so that the disc has enough room to swing and allow true, full disc contact with the seat.  The disc can be made entirely of metal, or can be inlaid with leather, rubber, or a synthetic cover, depending on performance requirements.Swing check valves in the fully open condition, the fluid pressure is virtually unimpeded, so the pressure drop through the valve is relatively small.

Lift check valve disc is located on the valve body seat sealing surface.The valve is like a globe valve, except that the disc can be lifted up and down freely. Fluid pressure lifts the disc from the seat sealing surface. Media back flow causes the disc to fall back to the seat and cut off the flow. Depending on the conditions of use, the disc may be of all-metal construction, or it may be in the form of a rubber pad or rubber ring mounted on the disc holder. Like the globe valve, the flow path through the lift check valve is narrow, so the pressure drop through the lift check valve is greater than that through the swing check valve, and the swing check valve flow is less restricted.