Centrifugal pump

That type of check valve is called an air release check valve, and it is usually installed vertically. The direct-through type is usually a lift-type check valve; a rod is connected to the valve stem, and this rod extends horizontally into the bypass port on the side. There is also a valve disc at the other end of this rod, which is used to control the minimum flow rate at the side port. When the pump is operating and the outlet valve is opened wide, the check valve flap rises, causing the linkage to block the minimum flow port; as a result, all of the pump’s flow exits through the normal pipeline ； When the opening degree of the outlet valve is small or the system backpressure increases, the check valve disc descends; at this point, the disc of the minimum flow line opens, allowing the pump to operate at the minimum flow rate without the need to shut down.