Valve type and principle-Check valve

The check valve is a valve that automatically opens and closes by the force of the fluid itself, and its function is to prevent the medium from flowing backward.

According to the structure can be divided into two categories：

（1）Lift check valve：The valve flap moves along the vertical centerline of the valve body.There are two types of check valves: one is horizontal, mounted on a horizontal pipe, the shape of the valve body is similar to a shut-off valve, and the other is vertical, mounted on a vertical pipe.

（2）Swing check valve：The valve disc rotates around the pin outside the seat.These valves have single, double and multiple lobes, but the principle is the same.

The suction bottom valve of the water pump suction pipe is a deformation of the check valve. The structure is the same as the above two types of valves, except that its lower end is open for water to enter.