The contribution of erosive wear to the performance degradation of sliding spool servovalves

Abstract

Flow conditions for sliding spool valves around their central position may be critical in terms of the resulting system performance. In-service changes that occur can cause a degradation of the performance of both the valve and the controlled system. The degradation due to erosive wear arising from solid particle contamination in the fluid flow is examined in detail in this paper. It reports the details of a test rig and methodology that has been carefully established to examine the effect of various factors on erosion wear. These factors include the contaminant particle size and concentration, differential pressure across the metering land, spool opening, spool surface hardness and flow direction, as well as fluid characteristics.