Valve Knowledge To Prevent Medium Backflow

The function of Lined 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 the fluid flowing in one direction, the valve disc opens; when the fluid flows in the opposite direction, the fluid pressure and the self-reclosing valve disc of the valve disc act on the valve seat, thereby cutting 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. The swing check valve has a hinge mechanism and a door-like valve disc freely resting on the inclined valve 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 disc can be made entirely of metal, or it can be inlaid with leather, rubber, or a synthetic covering surface on the metal, depending on the performance requirements. When the swing check valve is fully opened, 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 valve seat sealing surface on the valve body. This valve is similar to a stop valve except that the disc can be lifted freely. The fluid pressure lifts the disc from the valve seat sealing surface, and the medium reflux causes the disc to fall back onto the valve seat and cut off the flow. Depending on the conditions of use, the disc can be a full metal structure or a rubber pad or rubber ring can be embedded on the disc frame. Like a stop valve, the passage for fluid to pass through a lift check valve is also narrow, so the pressure drop through a lift check valve is larger than that of a swing check valve, and the flow of a swing check valve is less restricted.