Dynamic Characteristics of a Check Valve for Drain Pumps

Abstract

Check valves for checking reverse water flows in drainage systems sometimes make large impacts through their sudden closure caused by accidental cutoff of drain pumps. In order to characterize such phenomena and to find design criteria for impactless check valves, we observed the motion of a check valve and measured its impact acceleration and pressures in the drainage pipe, using a subscale drainage system. Two peaks of impact acceleration were observed; The first one seemed due to collision of the check valve and the valve seat, whereas the second one did due to water column separation and recombination caused by the low pressure during the contact of the valve with the seat. The former can be reduced by adding mass to the check valve and by setting an appropriate valve-seat angle. The latter possibly can be reduced by relaxing the low pressure during the contact. Subsequently, the check valve opened through the water-column recombination impacts.

In-line check valves for water hammer control

“…The valve's "slam" behavior is particularly crucial if there is an energy source, such as an air chamber of a still operating pump, near to the pump station (Purcell 1997). If there is a delay in the valve's response, so that a substantial reverse flow is established before the valve closes, sometimes destructive surge forces and pressures can be created (Sugiyama et al 2003). Yet, other than a quick sensitivity study to the issue of delay closure, these important issues are also considered beyond the scope of the work presented in this paper.…”

“…In this context the critical issue of modeling the valve's dynamic response has received considerable attention. Numerous authors (e.g., Thorley 1991, Chaudhry 1987, Li and Liou 2003, Sugiyama et al 2003) have explored the key issues of valve torque and inertia, of viscous and mechanical damping, and of the valve's structural/hydraulic response to flow. The pioneering work of Provoost (1980) and Thorley (1989) is significant while the recent work of Li and Liou (2003) represents a particularly thorough illustration of the modeling challenges.…”

Numerical Simulation of Transient Pressure Control in a Pumped Water Supply System Using an Improved Bypass Pipe

“…Check valves can prevent water pumps from rotating in reverse due to liquid backflow and thus prevent damage to the motor. However, instant check valve closure results in a catastrophically high pressure [7] and [8]. Therefore, when a check valve is installed in a pumping station to control transients, an air tank should also be installed near the pumping station to prevent the increase in pressure that results from closing the check valve [9].…”