Definition von viscosity index im Englisch Englisch wörterbuch
empirical, unitless number indicating the effect of temperature change on the kinematic viscosity of an oil Liquids change viscosity with temperature, becoming less viscous when heated; the higher the VI of an oil, the lower its tendency to change viscosity with temperature The VI of an oil - with known viscosity at 40°C and at 100°C - is determined by comparing the oil with two standard oils having and arbitrary VI of 0 and 100, respectively, and both having the same viscosity at 100°C as the test oil The following formula is used , in accordance with test method ASTM D 2270
Is a measure of the rate of change of viscosity with temperature Oils with high VI have low viscosity changes (010)
An empirical number indicating the effect of change in temperature on the viscosity of an oil A high viscosity index (VI) signifies a relatively small change of viscosity with temperature Ref ASTM D 2270-64
A measurement of viscosity with a change of temperatures A low VI (example 60) will thin out a lot at high temperatures whereas, a VI of 95 or higher will thin out less Some high grade oils already have naturally occurring high VI's Other VI's can be controlled through refinery processes or VI Improvers can be added
A commonly used measure of a fluid's change of viscosity with temperature The higher the viscosity index, the smaller the relative change in viscosity with temperature