Working principle

 Under the action of fluid pressure flowing in one direction, the valve page opens; When the fluid flows in the opposite direction, the pressure of the fluid and the self-overlapping flap of the flap act on the valve seat, thus cutting off the flow. Check valves belong to this type of valves, including swing check valves and lift check valves. The swing Check Valve has a hinge-chain mechanism, and a flap like a door rests freely on the inclined valve seat surface. In order to ensure that the valve flap can reach the proper position of the valve seat surface every time, the valve flap is designed in the hinge mechanism, so that the valve flap has enough swing space and makes the valve flap truly and comprehensively contact with the valve seat. The valve flap can be made entirely of metal, or it can be inlaid with leather or rubber, or it can be covered with synthetic surface, depending on the requirements of service performance. When the swing check valve is fully opened, the fluid pressure is almost unimpeded, so the pressure drop across the valve is relatively small. The flap of the lift check valve is located on the sealing surface of the upper seat of the valve body. In addition to the fact that the valve flap can lift freely. The rest is like the stop valve, the fluid pressure lifts the valve disc from the sealing surface of the valve seat, and the media backflow causes the valve disc to fall back to the valve seat and cut off the flow. According to the service conditions, the valve disc can be of all-metal structure, or it can be in the form of rubber pad or rubber ring embedded in the valve disc frame. Like the Globe Valve, the passage of fluid through the lift check valve is 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 rarely restricted.