Hydraulic fluids

Hydraulic fluids Hydraulic oils are also called hydraulic liquids or hydraulic fluids. They are the medium by which power is transferred in hydraulic equipment. Hydraulic fluids have the primary purpose of transferring potential or kinetic energy (pressure and movements), create volume flow between pump and hydrostatic motor, and reduce the wear of parts that rub against each other. In addition, they protect the system from corrosion and help carry away the heat produced during energy transformation. The operating practices of yesterday in industry have changed a lot. But steady and dependable, hydraulic fluid technology did not change much for decades. But today, the pressure is on hydraulic systems. Hydraulic systems are expected to deliver optimum performance while operating at higher pressures, temperatures, and tougher operating conditions. Common hydraulic fluids are based on mineral oil or water. These oils have generally low compressibility. Hydraulic oils are circulation quality oils since they are in continuous use in an enclosed system with practically very little residence time in a reservoir or a storage tank. Hydraulic fluid has to perform the following tasks: Energy transmission Lubrication Heat removal The primary function of a hydraulic fluid is to convey power. However there are other important functions of hydraulic oils such as protection of the hydraulic machine components. The main functions of hydraulic oil and the corresponding properties of the hydraulic oil which affects its ability to perform the required function are given below: Hydraulic oil as medium for power transfer and control needs low compressibility (high bulk modulus), fast air release, low foaming tendency and low volatility. Hydraulic oil as medium for heat transfer requires good thermal capacity and conductivity. Hydraulic oil as sealing medium must have adequate viscosity and viscosity index as well shear stability. For hydraulic oil to perform the function...

Lubricants

Lubricants A lubricant (also sometimes called as “lube”) is a substance (usually a liquid) introduced between two moving surfaces to reduce the friction between them which in turn improves the efficiency and reduces the wear. It also has the function of transporting foreign particles. A good lubricant possesses the following characteristics: High boiling point Low freezing point High viscosity index Thermal stability Hydraulic Stability Demulsibility Corrosion prevention High resistance to oxidation Lubrication is the process, or technique employed to reduce wear of one or both surfaces in close proximity, and moving relative to each other, by interposing a substance called lubricant between the surfaces to carry or to help carry the load (pressure generated) between the opposing surfaces. The interposed lubricant film can be a solid, (e.g. graphite and MoS2 etc.) a solid/liquid dispersion, a liquid, a liquid-liquid dispersion (a grease) or, exceptionally, a gas. Types of lubrication are shown in Fig 1. Fig 1 Types of lubrication Besides doing the function of lubricating, lubricants also carries out some or all of the following functions: Act as a coolant to remove the frictional heat which may be sometimes considerable. Keeps moving parts apart. Reduces friction between moving parts It dissolves and transports contamitants and debris arising both from internal and external sources. Acts as a hydraulic medium in some applications It protects against wear of highly loaded machine parts It prevents corrosion and rusting of machine parts It helps in transmitting power It offers protection against the accumulation of deposits (sludges and varnish) in lubrication system. It acts as a seal for gases It resists aeration and foaming, which can cause mal-functioning It resists or aid emulsion formation in wet systems. It stops the risk of smoke and fire of objects It has ability...