Select the right type of check valve for water hammer protection has a great impact, for example, a large number of pumping water hammer accident is a pump outlet installed with the check valve. After pumping accident in Beijing began to flow back, in reverse leakage currents of the role, check valve closed quickly, if the check valve due to failure or bearing friction and inertia effects, check valve may be delayed to begin to turn the clock back, namely the down flow increased to a certain value, even in the moment of maximum flow rate down quickly shut down can in the check valve generated at very large pressure. Check valve valve at the flow rate of zero closure is closed to the best state, it is not possible to complete the valve at the flow rate is zero. It is generally believed that, as long as the zero flow near the closed end is normal.
