![]() ![]() ![]() Viscosity is just one of many properties used to analyse lubricants and assess suitability for different applications. A holistic approach to lubricant analysis Most lubricants offer Vis ranging from between 90 to 160, though some can be as low as -60 or as high as 400. Today, ASTM D2270 Standard Practice for Calculating Viscosity Index from Kinematic Viscosity at 40 ☌ and 100 ☌ is one of the most widely used methods to calculate VI. Viscosity Index helps operators make informed decisions to prepare for these changes and minimise the risk of unplanned downtime. Temperature changes can and do occur, triggered by anything from weather patterns to mechanical overheating. VI allows operators to compare how different lubricants behave when exposed to temperatures outside normal operating conditions. ![]() This is usually a mistake as VI can have a big impact on how a lubricant performs when in circulation and exposed to temperatures other than the standard 40☌ used to calculate viscosity. Viscosity index calculation was performed with a computer program using kinematics viscosity at 40☌ and 100☌. Viscosity index was calculated from the measured viscosity at 40☌ and 100☌ using ASTM Method D 2270 and was graphically determined using ASTM D 341. Why Viscosity Index mattersĪs mentioned earlier, Viscosity Index is often disregarded during the lubricant selection process. In this paper viscosity index of hydraulic oil was determined using tree methods. A higher VI number indicated more stability when exposed to temperature changes. Pennsylvania crude was given a VI of 100 while Texas Gulf crudes were given a VI of 0. Using Pennsylvania crude as a benchmark for low viscosity and Texas Gulf crudes for high viscosity, the team developed a method for calculating changes in internal resistance to flow relative to temperature. The concept of Viscosity Index was first developed in the 1920s by a pair of American chemists. VI is an independent parameter and is used to calculate how viscosity will change when exposed to temperatures higher or lower than 40☌. Viscosity Index vs ISO Viscosity GradeĬontrary to popular belief, Viscosity Index is not part of ISO Viscosity Grade, which calculates viscosity at a standard temperature of 40☌. While VI is often an overlooked parameter when selecting lubricants, it can offer valuable insight into how the lubricant will behave when in use. 1 This practice 2 covers the procedures for calculating the viscosity index of petroleum products, such as lubricating oils, and related materials from. Temperature-triggered changes in the viscosity of a lubricant is known as Viscosity Index (VI). 12 (6), 942–949 (2020).Viscosity can vary enormously between different lubricants and temperature often plays a key role in changing internal resistance to flow. Dubovik, “On modeling a layered viscous conductive fluid flow in a region changing in time,” Math. Bogoyavlenskij, “On the Kelvin’s 1880 problem and exact solutions of the Navier–Stokes equations,” Steklov Mathematical Institute Seminar “ Mathematics and Its Applications,” May 21, 2015, Moscow, Conference Hall (Gubkina 8). Arnold, “Sur la topologie des écoulements stationnaires des fluides parfaits” C. Sheretov, “On solutions of the Cauchy problem for a quasi-hydrodynamic system,” Vestn. Trkal, “A note on the hydrodynamics of viscous fluids,” Czech. Dubovik, “Exact solutions of incompressible Navier–Stokes equations in the case of oil and gas industrial problems,” Dokl. Galkin, “Control of incompressible fluid parameters in the case of time-varying flow geometry,” Dokl. ![]()
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