Check Valve Closure Behaviour; Experimental Investigation and Simulation in Waterhammer Computer Programs
A standard of comparison for undamped check valves with respect to the closure behaviour is the dynamic characteristic. The pressure surges due to valve closure and the degree of check valve slam are directly related to this characteristic.
A general method is proposed to perform dynamic tests and to elaborate test results into dynamic characteristics. The method is based on results of an experimental investigation on the influence of the initial flow on the closure behaviour of check valves (initially fully open) and the influence of the valve itself on the flow during closure. Measurement data are processed taking time shift effects into consideration.
Recent developments are to present the dynamic characteristic in a dimensionless form. Theoretically the curves of geometrically similar check valves coincide. Moreover the curves of spring loaded check valves coincide when applying different springs.
The usefulness of the dimensionless characteristic is investigated for several spring loaded nozzle check valves up to diameters of 800 mm for various springs.
Based on the dynamic characteristic a method is presented for simulation of check valve closure behaviour in waterhammer computer programs.
The method is valid for all types of undamped checkvalves and may be useful to system engineers in the selection of check valves.
Examples of applications are included.
KeywordsDynamic Characteristic Critical Velocity Dynamic Test Valve Closure Check Valve
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