The slam check valve, also called the non slam check valve, is an automatic valve. It 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 in the pipeline from flowing back, which plays a great role in ensuring the safety of the pipeline.
It can be divided into three types: lift check valve, swing check valve and non slam check valve. Lift check valves can be divided into two types: vertical and straight-through. Swing check valves are divided into three types: single valve, double valve and multi valve. Non slam check valves are divided into butterfly double flaps and butterfly single flaps. The above-mentioned slam check valves can be divided into four types in connection form: threaded connection, flange connection, welding and wafer connection.
The slam check valve is installed to ensure the flow direction of the water inside the pump, so as to ensure the normal operation of the pump. Therefore, regarding the installation position of the slam check valve, whether it is installed in front of the pump or after the pump, there are two situations:
(1) Installed at the end of the vertical suction pipe in front of the water pump, also called the bottom valve. The purpose is to fill the pump without pumping water all the time, because when there is no water in the pump and the suction pipe in front of the pump, the pump can only be idling and cannot pump water, so the pump must be filled with water to pump out water. This kind of water pump installation is higher than the liquid level, also called the negative pressure method.
(2) The slam check valve is installed behind the pump. This installation method is convenient for starting and stopping the pump without closing the outlet valve when the liquid level is higher than the pump, especially for the pump in the main control system to prevent backflow.
The slam check valve must be installed at the outlet of the pump, before the outlet control valve, so that the check valve can be overhauled. Generally, the first outlet of the pump is the soft connection (shock absorber), the next is the check valve, and then the isolation valve (such as butterfly valve, gate valve, stop valve, etc.).