Valve friction quantification: Industrial case studies

Abstract

Control valves are the main final elements of control loops in industrial processes. When a valve is affected by friction, it causes oscillations or steady-state errors in the stem position, since the valve does not respond instantaneously to the control signal. Hence, the presence of friction can increase the variability of the control loop, causing loss of product quality and increasing the need of maintenance, in such a way to generate economical impacts. Many studies have been presented in order to diagnose and measure the valve friction. In this work, some techniques proposed in the literature are implemented. In order to evaluate its performance, some comparisons of the results obtained from industrial data are presented. © 2011 IFAC.