The check valve
can be used to supply a line in which the pressure may rise to an auxiliary system that exceeds the system pressure. The check valve can be mainly divided into a swing type check valve (rotation according to the center of gravity) and a lift check valve (moving along the axis).
Check Valves The role of this type of valve is to allow only the medium to flow in one direction and to prevent flow in the opposite direction. Usually, the valve is automatically operated, and the valve flap is opened by the fluid pressure flowing in one direction; when the fluid flows in the opposite direction, the fluid pressure and the self-reclosing valve flap of the valve disc act on the valve seat to cut off the flow.
Among them, the check valve belongs to this type of valve, which includes a swing check valve and a lift check valve. With the swing-open check valve fully open, the fluid pressure is almost unimpeded, so the pressure drop across the valve is relatively small. The valve flap of the lift check valve is located on the valve seat sealing surface of the valve body. In addition to the flap being free to lift and lower, the valve is like a shut-off valve. The fluid pressure causes the flap to lift from the seat sealing surface. The backflow of the medium causes the flap to fall back onto the seat and shut off the flow. Like the shut-off 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 rate of the swing check valve is limited. Very few.