Bernhard Manhartsgruber, Bernd Winkler,
"Flow Characteristics Measurement of Large Valves"
, in D N Johnston and A R Plummer: Power Transmission and Motion Control - PTMC 2007, Seite(n) 449-458, 9-2007, ISBN: 978-0-86197-140-4
Flow Characteristics Measurement of Large Valves
Sprache des Titels:
Power Transmission and Motion Control - PTMC 2007
The functional relationship between the flow rate through a hydraulic resistance and the occuring pressure drop is fundamental for the design and analysis of fluid power systems. In the case of valves, a standardized procedure for the measurement of the flow rate vs. pressure drop characteristics is given in ISO 4411. However, the test rig for an experiment according to this standard is quite expensive in the case of large valves. The largest commercially available cartridge valves have a flow capacity of 25000 l/min. In order to measure their flow characteristics according to ISO 4411, the test rig has to deliver this flow rate over some period of time. The second problem is the cost for a flow meter of this size. Typically, valve test rigs are only available up to flow rates of a few hundred litres per minute. If the flow capability of the valve to be tested is in the thousands of litres per minute, valves can often only be tested in the application but not in a laboratory.
This paper describes a new approach for the measurement of the flow characteristics of large valves by the use of a pressurized column of oil in a pipeline. During an opening instant of the device under test, several pressure signals are recorded and used for an analysis based on the Joukowsky relation between pressure and flow rate. This valve opening experiment can be repeated at different pressure levels resulting in a pointwise determination of the pressure drop vs. flow rate function. The method has experimentally been checked against the conventional flow-meter approach with a cartridge valve of nominal size 16 mm at flow rates up to 150 l/min. A large scale test rig for flow rates up to 4000 l/min is under consideration.