Check Valve Working Principle

Check valves may also be used on lines supplying auxiliary systems where the pressure may rise above 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 function of this type of valve is to allow the medium to flow in one direction only and prevent the flow in the opposite direction. Usually this kind of valve works automatically. Under the pressure of fluid flowing in one direction, the valve disc opens; when the fluid flows in the opposite direction, the fluid pressure and the self-weight of the valve disc act on the valve seat, thereby cutting off the flow.
Among them, check valves belong to this type of valve, which include swing check valves and lift check valves. The swing check valve has a hinge mechanism and a door-like valve disc that freely rests on the inclined seat surface. In order to ensure that the valve disc can reach the appropriate position of the valve seat surface every time, the valve disc is designed in the hinge mechanism so that the valve disc has enough swing space and makes the valve disc truly and comprehensively contact the valve seat. The valve flap can be made entirely of metal, or it can be inlaid with leather, rubber, or synthetic coverage on the metal, depending on the performance requirements. When the swing check valve is fully open, the fluid pressure is almost unimpeded, so the pressure drop through the valve is relatively small. The valve disc of the lift check valve is located on the sealing surface of the valve seat on the valve body. Except that the valve disc can rise and fall freely, the rest of this valve is like a stop valve. The fluid pressure causes the valve disc to lift from the sealing surface of the valve seat. The backflow of the medium causes the valve disc to fall back to the valve seat and cut off the flow. Depending on the conditions of use, the valve disc can be an all-metal structure, or it can be inlaid with a rubber pad or rubber ring on the valve disc frame. Like the stop valve, the passage of fluid through the lift check valve is also narrow, so the pressure drop through the lift check valve is larger than that of the swing check valve, and the flow of the swing check valve is limited. rare.