Check Valve Closure Behaviour; Experimental Investigation and Simulation in Waterhammer Computer Programs

Check valves are used to minimize flow reversal. In general, the two primary design objectives of installing a check valve in a system include quick opening in forward flow and fast closure in reverse flow. The fast response requirements in both opening and closing directions are challenging. In the opening direction, the concern is to minimize forward flow resistance and, in the reverse direction, the objective is to minimize flow reversal and avoid water hammer. Check valve manufacturers have often used counterweights to permit quick opening or quick closing. The drawback of forward flow counterweight check valves is that in the flow reverse direction, the counterweights may retard valve closure. The location of the counterweight could further complicate the performance of the check valve. Misaligning the counterweight can also affect check valve performance. The use of quick closing counterweights present similar challenges. This paper examines the interaction of counterweight location and alignment on the performance of check valves.

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Pressure Transients Caused by Tilting-Disk Check-Valve Closure

Journal of Hydraulic Engineering ◽

10.1061/(asce)hy.1943-7900.0000958 ◽

2015 ◽

Vol 141 (3) ◽

pp. 04014081 ◽

Cited By ~ 7

Author(s):

Phu D. Tran

Keyword(s):

Check Valve ◽

Valve Closure ◽

Pressure Transients

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Towards an Improved Understanding of Water-Hammer Column-Separation Due to Rapid Valve Closure

ASME 2010 Pressure Vessels and Piping Conference: Volume 7 ◽

10.1115/pvp2010-26146 ◽

2010 ◽

Cited By ~ 2

Author(s):

H. A. Warda ◽

Y. Elashry

Keyword(s):

Transient Flow ◽

Computer Software ◽

Check Valve ◽

Cavity Formation ◽

Valve Closure ◽

Time Step ◽

Vapor Cavity ◽

Cavity Collapse ◽

Column Separation ◽

Video Frames

Column separation phenomenon occurring downstream of a closing valve, simulating the closure of non-return/check valve downstream of pumps due to pump trip is simulated. An improved understanding of how cavity is opened, grows and collapses is supported by comparing numerical results with measured values and analyzing video frames. In the present study two models, discrete vapor cavity and gas cavity models, of column separation are compared for the modeling of column separation. Both models showed considerable degree of stability with variation of number of sections into which the pipe is divided. An experimental setup was built to provide the means of obtaining reliable experimental data for transient flow in viscoelastic pipes to verify the numerical model. Two valve closure schemes were tested using solenoid globe and ball valves. Video photographs of column separation during the vapor cavity formation, growth and collapse were processed and video films are transformed into frames using computer software. The video frames representing the cavity development and pressure measurements downstream of the valve are compared with corresponding cavity and pressure traces predicted by the model at each time step of the framing process at the same location. It was also shown that the characteristic of check valve closure scheme seriously affects the cavity formation and the extent of pressure surges due to cavity collapse.

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Charts for water hammer in low head pump discharge lines resulting from water column separation and check valve closure

Canadian Journal of Civil Engineering ◽

10.1139/l84-092 ◽

1984 ◽

Vol 11 (4) ◽

pp. 717-742 ◽

Cited By ~ 1

Author(s):

Eugen Ruus ◽

Bryan Karney ◽

Farouk A. El-Fitiany

Keyword(s):

Water Column ◽

Pressure Rise ◽

Check Valve ◽

Pressure Head ◽

Maximum Pressure ◽

Valve Closure ◽

High Point ◽

Column Separation ◽

Discharge Line ◽

Low Head

Maximum pressure head rises resulting from water column separation and check valve closure are calculated and plotted for a simple low head pump discharge line with one well-defined high point. Basic parameters such as pipeline constant, pipe wall friction, complete pump characteristics, pump inertia constant, and the relative location of the high point are accounted for in the analyses. The results of this paper can be used to determine (a) when water column separation is expected, (b) how to avoid water column separation, and (c) the necessary wall thickness in cases where no protection against water column separation is provided. Computer studies indicate that both the vertical and horizontal location of the high point as well as the pipe friction, the pipeline constant, and the pump inertia have a major effect on pressure head rises. Water column separation does not always constitute a danger to the pipeline. Key words: waterhammer, water column separation, check valve closure, pressure rise, pump discharge line, chart.

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