Vertical check valve: due to the pressure of the inlet medium in the pipeline, and overcome the spring resistance to open or close the valve. When the inlet end medium pressure is lower than the outlet end, the spring will push the valve core to the valve seat and make the valve close, prevent the medium from countercurrent, so the start and stop action. Vertical check valve is widely used in chemical, liquefied petroleum gas, fluid and other industries. Check valve according to the structure, can be divided into lifting type check valve, swing type check valve and butterfly check valve three.