A check valve, also known as a check valve, is an automatic valve that relies on the pressure of the flowing medium in the pipeline to push the valve disc to close and open the valve. When the medium stops flowing, the check valve disc closes, effectively preventing the medium from flowing back in the pipeline, which plays a significant role in ensuring the safety of the pipeline.

Check valves can be divided into three types according to their structure: lift check valves, swing check valves, and butterfly check valves. Lift check valves can be divided into two types: vertical and straight through. Swing check valves are divided into three types: single disc, double disc, and multi disc. Butterfly check valves are divided into butterfly double disc and butterfly single disc. The above types of check valves can be connected in four ways: threaded connection, flange connection, welding, and wafer connection.

The installation of a check valve is to ensure the flow direction of water inside the water pump, thereby ensuring the normal operation of the water pump. So, regarding the installation position of the check valve, whether it is installed in front of or behind the water pump can be divided into two situations:

1.One type is installed at the end of the vertical suction pipe in front of the water pump, also known as the bottom valve. The purpose is to fill the water pump with water without having to pump it once, because when there is no water inside the pump and the suction pipe in front of the pump, the pump can only idle and cannot pump water. Therefore, the pump must be filled with water in order to pump out water. The installation of this type of water pump is a method above the liquid level, also known as negative pressure method.

2.Another type is installed behind the water pump. This installation method is convenient for starting and stopping the water pump without closing the water outlet valve when the liquid level is higher than the water pump, especially for the main pipe water pump system to prevent backflow.