Resistance coefficients of mineral tailings flowing in diaphragm control valves

Abstract

The need to save water world-wide is forcing industry to reduce water consumption which in turn leads to increasing concentrations of the mineral tailings handled. Design criteria are shifting from turbulent flow to laminar flow. Although diaphragm valves are used extensively to control flow, there is very little experimental data available. The use of the incorrect resistance coefficient could lead to inefficient designs. The objective of this paper is to provide experimentally determined resistance coefficient data for 5 diaphragm valves ranging from 40 mm – 100 mm, in the fully open, 75%, 50% and 25% open position for laminar and turbulent flow. The problems encountered in establishing dynamic similarity for these valves and the effect that this has on the resistance coefficients is discussed. The resistance coefficients obtained for valves produced by different manufacturers are compared. The results are provided to facilitate more accurate and efficient designs.