Water‐based hydraulic fluids containing synthetic components

This paper explains the nature offire-resistant, water-based hydraulic fluids, and their applications, and gives comparisons with mineral oil-based hydraulic fluids. The content of the different types of fluid is described, and the technical requirements for water-based hydraulic fluids discussed. The chemistry of the synthetic thickeners of water, their thickening effect and shear stability, as well as their technical properties, are explained and compared. The construction and the mode of action of thickeners for hydraulic fire-resistant fluids (HFAS) or viscous high-water-based fluids (VHWBF) are detailed, and the physical chemistry of these hydrophilic-hydrophobic thickeners, which form microemulsions in water, is considered in interaction with emulsifying agents. In this case laser-light scattering correlation spectroscopy is shown to be helpful.