The bottom valve is installed at the inlet end of the pump to ensure that the inlet end of the pump is filled with liquid.

The bottom valve is a lift check valve installed on the bottom end of the suction pipe of the centrifugal pump, so it is called the "bottom valve". Before the pump starts, the disc is closed because of self weight, and the water can be filled with suction pipes at the upper part of the bottom valve. After the pump is started, suction in the suction pipe improves the bottom valve disc, so that the water flows into the pump continuously. After the pump stopped, the suction disappeared and the bottom valve closed itself.

The bottom valve is a special lift check valve installed at the suction end of the pump pipe. Most pumps require water to be injected before pneumatics to drain air from the pump housing and suction pipe. A check valve is required to prevent the loss of the injected liquid.

The pump housing and suction pipeline may be filled with liquid by manual dumping, or by applying a vacuum to the pump housing to induce liquid into the pipeline and pump housing. Under these two conditions, the bottom valve can prevent the charged liquid from directly discharging or emptying the air of the pump housing. Bear in mind that the suction system of the bottom valve is a drag retardant, resulting in the loss of suction pressure of the pump. This drag retardant must be taken into account in the design of the pipeline and in the selection of the valve.