Check valve is to rely on the media itself and automatically open the valve, closed valve, used to prevent the media back to the valve, also known as check valve, check valve, counter valve and back pressure valve. Check valve is an automatic valve, its main role is to prevent the media back to prevent the pump and drive the motor reversal, and the container media discharge. The check valve can also be used on piping where the pressure may rise above the supply of the auxiliary system. Check valve can be divided into swivel check valve (according to the center of gravity rotation) and lift check valve (along the axis of movement).
Check Valve This type of valve functions only to allow the media to flow in one direction and to prevent the opposite direction from flowing. Usually the valve is automatically working, in a direction of the flow of fluid under pressure, the valve flap open; fluid flow in the opposite direction, by the fluid pressure and the valve flap from the valve seat in the valve seat, thus cutting the flow.
The check valve belongs to this type of valve, which includes a swivel check valve and a lift check valve. The swivel check valve has a hinge mechanism, and a valve-like valve flap free to rest on the inclined seat surface. In order to ensure that the valve flap reaches the proper position of the valve seat each time, the flap is designed in the hinge so that the flap has sufficient swivel space and the flap is truly and fully accessible to the valve seat. The flap can be made entirely of metal, or it can be embedded in metal with leather, rubber, or synthetic coverage, depending on the performance requirements. Swing check valve in the fully open condition, the fluid pressure is almost unimpeded, so the pressure drop through the valve is relatively small. The flap of the lift check valve is located on the valve seat sealing surface of the valve body. This valve in addition to the valve can be free to lift, the rest as the same as the valve, the fluid pressure to the valve from the valve seat sealing surface lift, the media back to the valve back to the valve seat, and cut off the flow. Depending on the conditions of use, the flap may be of the all-metal structure and may be in the form of a rubber pad or rubber ring in the flap frame. Like the shut-off valve, the passage of the fluid through the lift check valve is also narrow, so the pressure drop through the lift check valve is larger than the swivel check valve and the flow of the swivel check valve is limited Very few
The function of the check valve in the pump water supply system is to prevent the impact of the high pressure water return on the pump impeller. The system in operation due to some reason, the pump suddenly stopped running, the pump pressure disappears, and the pump outlet connected to the high-pressure water will reverse flow back to the pump. When the pump outlet is equipped with a check valve, it closes immediately to prevent high pressure water from flowing back to the pump.
The function of the check valve in the hot water system is to prevent hot water from flowing back into the pipe. If it is PVC pipe is likely to burn pipe, and may even hurt, especially in the solar water heater system.