Where should the check valve be installed?

A check valve, also known as a non-return valve, is a fully automatic valve. It uses the working pressure of the flowing medium in the pipeline to actuate the valve disc, completing the opening and closing of the valve. When the medium stops flowing and the check valve disc closes, it effectively prevents backflow of the medium in the pipeline, which is very effective in ensuring pipeline safety.

Check valves can be classified by structure into regulating check valves, swing check valves, and lift check valves. Regulating check valves can be divided into vertical check valves and inline check valves. Swing check valves are divided into single-flap, double-flap, and multi-flap types. Lift check valves are divided into butterfly double-flap and lift single-flap types. The above check valves can be divided into four types of connections: flange connection, flange connection, welding, and clamp connection.

Check valves are installed to ensure the flow direction in the pump, thereby ensuring the normal operation of the pump. Therefore, the installation location of the check valve can be divided into two situations:

One is installed at the top of the vertical suction pipe in front of the pump, also known as the pump foot valve. The purpose is to prime the pump with water once, because when the pump and the suction pipe in front of the pump are without water, the pump only runs at high speed and cannot pump water, so the pump must be filled with water to pump water. This pump installation is a method that exceeds the liquid level, also known as the negative pressure method.

Another is installed after the pump. This installation method is convenient for starting and stopping the pump without turning off the pump inlet and outlet valves when the liquid level is higher than the pump, especially for the main pipe centrifugal pump system, to prevent backflow.

The check valve must be installed at the pump outlet and before the outlet pressure regulating valve to protect the check valve. Generally speaking, the pump's first outlet is a flexible conductive connection (vibration damper), followed by a check valve, and then a shut-off valve (such as a butterfly valve, globe valve, gate valve, etc.)