Research on the Performance of Check Valve at a Long Distance Pumping System

Abstract

Experimental investigations of dynamic characteristics of the check valve are a contribution work to provide boundary condition to check valve mathematical simulation. The closure process of the check valve was tested. The changing processes of inlet and outlet pressure were performed. Based on the experiment system and the measured quantities, mathematical models were established to study the test. Numerical calculation was mainly focus on when valve starting to close and the closing characteristic time. The paper simulated the different minimum velocities that the valve started to close at. Simulation results approximated to test data when the check valve started to close at a larger flow velocity and a shorter closing characteristic time. The closing characteristic time was discussed when check valves closing on a certain velocity. Following the closure rule of check valve got during the simulation, the paper studied the check valve acting on a long distance pumping system. Two part contents were studied: only check valve arranged along pipeline, both air admission valve and check valves arranged. Along the pipeline seven check valves were arranged, the pump power failure condition was calculated and check valves were closed because of the flow velocity decreased. The result showed negative pressure was large when installed just a finite number of check valves along pipeline. Gas admission valves were arranged to negative pressure prevention. Two check valves were respectively arranged at the pump outlet and pipeline. The pressure transient peak at pump outlet will be dropped a lot with the check valve at pipeline closed; the maximum pressure transient peak along pipeline is appeared at check valve outlet on the pipeline under the pump power failure condition. The negative pressure in front pipes could be prevented by installing gas admission valve. Through the check valves and gas admission valves combined action, both the pressure and backflow were well controlled.