Issue link: http://read.dmtmag.com/i/859318
Hydraulic Fluids Background & Properties castrol.com/GPS 800 255 4417 May 2025 GPS Important Anti-wear Hydraulic Fluid Properties By definition, any fluid whose pressure and flow is used to produce work is considered a hydraulic fluid. For this and reasons of convenience, a multitude of different lubricants have found their way into the hydraulic sump. Without a formal industry specification, it can be difficult to decide on the best fluid for hydraulic equipment. A hydraulic fluid must be able to perform the following tasks: • Transmit power; • Provide a viscous seal; • Maintain system pressure; • Transfer heat to cool the system; • Prevent rust and corrosion; • Guard against foaming; • Separate water from oil for easy removal; • Be thermally and hydrolytically stable; • Lubricate components; and • Maintain long service life. Selecting a hydraulic fluid that can meet the above criteria centers on determining the following fluid properties: What is the base stock used in the fluid? Does the oil separate from or combine with water? How does the oil deal with water contamination? How does the anti-wear additive react with water? What is the viscosity index of the fluid? Base Fluid Base fluid selection and its inherent performance characteristics are important to the formulation of a premium-performing AW hydraulic fluid. Although base oil must be enhanced with additives of varying treat rates, they are expensive. It can be tempting for oil marketers to choose lower cost base stocks and standard treat levels to create a lower priced fluid. Consequently, decreased performance will result from these choices. H H H H H H Non-Saturated Base Oil Oxidized Oil C C C C H H C C H H – – – – – = = O H H H C C C C H H C C H – – – – – – – = O = O = O = H H H C C C C H H C C H H H H H H H – – – – – – – H H Saturated Base Oil C9 Oxygen can easily attach to available carbon molecules Oxygen has reacted with available carbon and oxidation occurs No oxygen can attach because oil is "saturated'' with hydrogen ecastrof