Measurements of DN150/DN200 control valves

These measurements aimed at the evaluation of the /flow resistance dependent of the pre-set position of a defined valve. This so-called k_v-value is being measured under stationary conditions with the test medium water according to IEC 60534-2-3 and then calculated as of the flow rate or pressure difference. The Institute’s test rig enables us to measure and test rather large valves conforming to standards. Furthermore, maximum flow rates of more than 300 l/sec and pressure differences of more than 8 bar could be realised for this measurement campaign.

These significant volumes and/or pressures were necessary to trigger cavitation within the valve and thus depict behaviour under choked flow conditions. This choked flow state caused by maximum/total cavitation is important for the assessment of maximum flow rate and/or choked flow conditions caused by cavitation in real-life operation.

Apart from cavitation measurements based on flow rate and pressure difference, the cavitation behaviour could also be assessed by means of acoustic measurements as a sharply increasing acoustic level is an unmistakeable sign that cavitation occurs. In future, simple on-site acoustic measurements in plants and calculations based on the determined xFZ parameter will enable the definition of the capacity and operation mode of a certain valve and thus contribute to increased plant safety.