Thread check valve refers to a valve that automatically opens and closes the valve disc by relying on the flow of the medium itself to prevent medium backflow. It is also known as a check valve, one-way valve, backflow valve, and backpressure valve. The threaded check valve is an automatic valve that mainly functions to prevent medium backflow, prevent pump and drive motor reverse rotation, and discharge the container medium. The threaded check valve can also be used to supply pipelines to auxiliary systems where the pressure may rise above the system pressure. Thread check valves can be mainly divided into swing type thread check valves (rotating according to the center of gravity) and lift type thread check valves (moving along the axis).

The function of a threaded check valve is to only allow the medium to flow in one direction and prevent flow in the opposite direction. Usually, this type of valve operates automatically, and under the pressure of fluid flowing in one direction, the valve disc opens; When the fluid flows in the opposite direction, the valve seat is cut off by the fluid pressure and the self closing of the valve disc, which acts on the valve seat.

Among them, threaded check valves belong to this type of valve, which includes swing type threaded check valves and lift type threaded check valves. The swing type threaded check valve has a hinge mechanism and a valve disc that is like a door and freely rests on the tilted valve seat surface. In order to ensure that the valve disc can reach the appropriate position on the valve seat surface every time, the valve disc is designed in a hinge mechanism, so that the valve disc has sufficient swing space and truly and comprehensively contacts the valve seat. The valve disc can be made entirely of metal, or it can be embedded with leather, rubber, or a synthetic cover on the metal, depending on the performance requirements. When the swing type threaded check valve is fully open, the fluid pressure is almost unobstructed, so the pressure drop through the valve is relatively small. The disc of the lift type threaded check valve is located on the sealing surface of the valve seat on the valve body. Except for the free lifting and lowering of the valve disc, the rest of this valve is like a globe valve. Fluid pressure lifts the valve disc from the sealing surface of the valve seat, and the medium backflow causes the valve disc to fall back onto the valve seat, cutting off flow. According to the usage conditions, the valve disc can be an all metal structure, or it can be in the form of embedded rubber pads or rings on the valve disc holder. Like a globe valve, the passage of fluid through a lift type threaded check valve is also narrow, so the pressure drop through the lift type threaded check valve is greater than that of the swing type threaded check valve, and the flow rate of the swing type threaded check valve is limited very little.