The difference between backflow preventer and check valve

Both backflow prevention valve and the check valve have function of preventing backflow, but two of them have essential differences. The backflow prevention valve is consist of two spaced-apart check valves and a drain valve. Due to the partial head loss of the check valve, the pressure in the intermediate chamber is always lower than the pressure at the water inlet. This pressure differential drives the drain valve to a closed state and the line is properly supplied with water. When the pressure is abnormal (ie, the pressure at the outlet end is higher than the intermediate chamber), even if the two check valves are not reverse sealed, the safety drain valve can be automatically opened to discharge the return water and form an air partition to ensure the upstream water supply.

1. Anti-backflow valve set a strict limit on the water in the pipeline under the current water supply pipe network situation in China. Especially when the drinking water pipeline has serious backflow pollution, and there is no effective prevention of backflow pollution device. It is a new hydraulic control unit (anti-return valve).

2. The backflow prevention valve consists of two separate check valves and one hydraulically driven drain valve. Due to the partial head loss of the check valve, the pressure in the intermediate chamber is always lower than the pressure at the water inlet. This pressure differential drives the drain valve to a closed state and the line is properly supplied with water. When the pressure is abnormal (ie, the pressure at the outlet end is higher than the intermediate chamber), even if the two check valves are not reverse sealed, the safety drain valve can be automatically opened to discharge the return water and form an air partition to ensure the upstream water supply. Health and safety. A hydraulic control combination strictly limits the pressure water in the pipe and can lead the medium to flow in one direction.

Check valve: Check valve’s function is to prevent backflow of the medium in the pipeline. The valve is opened or closed by the force of the medium, to prevent backflow of the medium.

Check valve is an automatic valve type, mainly used for one-way flow of medium in the pipeline, only allowing the medium to flow in one direction to prevent accidents. The check valves are classified according to the structure and can be divided into three types: lift check valves, swing check valves and butterfly check valves. The lift check valve can be divided into vertical and horizontal swing check valves, which are divided into single valve, double valve and multi-leaf. The butterfly check valve is straight-through. The above several check valves can be divided into three types: threaded connection, flanged connection and welding. The check valve is a valve that automatically prevents fluid from flowing backwards. The valve flap of the check valve opens under fluid pressure and fluid flows from the inlet side to the outlet side. When the inlet side pressure is lower than the outlet side,