The equivalent reverse velocity is calculated from Equation 2. Figure 6 also show the dual plot from both a pressure transducer and an accelerometer. The peak vibration occurred at the closure of the check valve. Figure 7 is a comparison plot of the tests of three different check valves tested at different initial velocities. Figure 7 demonstrates that the relationship between reverse velocity and flow deceleration is independent of initial velocity as long as the test valve is fully open at the initial velocity.
Reverse velocities are greater for valves with larger strokes or travel of components to close.
Reverse velocities are less for valves that were spring assisted to close. These conclusions are justified because of the increased time necessary to accelerate and overcome the inertia of valve internals and the distance they must travel. The slope or orientation of the pipeline has a significant effect on reverse velocities. An upward slope will usually cause a decrease in reverse velocity, and a downward slope will increase the reverse velocity. The wear of flow components can also have a significant effect on reverse velocity.