Wear and fatigue problems in connection with water‐based hydraulic fluids

Water-containing fluids are widely used in hydraulic applications where there is a significant risk of fire, as in underground mining and metal working applications. Although primarily intended as power transmitting media, hydraulic fluids need to possess a modicum of lubricating ability to limit wear, seizure and contact fatigue of pumps and other rubbing parts. Unfortunately water-based hydraulic fluids generally show significantly poorer wear and rolling-contact fatigue performance than mineral or synthetic oil-based fluids of similar viscosity and this means that pumping equipment usually has to be derated when used with water-based fluids. This paper examines the poor wear and fatigue performance of water-based fluids and discusses, in some detail, the origins of this poor performance and the ways it can be mitigated.