Search results
Results from the WOW.Com Content Network
A 10W-30 oil must pass the SAE J300 viscosity grade requirements for both 10W and 30, and all limitations placed on the viscosity grades, such as the requirement that a 10W oil must fail the 5W requirements. Viscosity index improvers (VIIs) are special polymer additives added to oil, usually to improve cold weather performance in passenger ...
The higher the VI, the more stable the viscosity remains over some temperature range. The VI was originally measured on a scale from 0 to 100; however, advancements in lubrication science have led to the development of oils with much higher VIs. [1] The viscosity of a lubricant is closely related to its ability to reduce friction in solid body ...
The grades include single grades, such as SAE 30, and also multi-grades such as SAE 15W-30. A multi-grade consists of a winter grade specifying the viscosity at cold temperatures and a non-winter grade specifying the viscosity at operating temperatures. An engine oil using a polymeric viscosity index improver (VII) must be classified as multi ...
Consequently, if a liquid has dynamic viscosity of n centiPoise, and its density is not too different from that of water, then its kinematic viscosity is around n centiStokes. For gas, the dynamic viscosity is usually in the range of 10 to 20 microPascal-seconds, or 0.01 to 0.02 centiPoise. The density is usually on the order of 0.5 to 5 kg/m^3.
The proportionality factor is the dynamic viscosity of the fluid, often simply referred to as the viscosity. It is denoted by the Greek letter mu ( μ ). The dynamic viscosity has the dimensions ( m a s s / l e n g t h ) / t i m e {\displaystyle \mathrm {(mass/length)/time} } , therefore resulting in the SI units and the derived units :
Dimensionless numbers (or characteristic numbers) have an important role in analyzing the behavior of fluids and their flow as well as in other transport phenomena. [1] They include the Reynolds and the Mach numbers, which describe as ratios the relative magnitude of fluid and physical system characteristics, such as density, viscosity, speed of sound, and flow speed.
Viscosity index (ASTM D2270 [11]) is a measure of the extent of viscosity change with temperature; the higher the VI, the less the change. VI is calculated from viscosity measurements at 40°C and 100°C. The viscosities of paraffinic and naphthenic base oils have very different behavior with temperature change.
One can convert efflux time to kinematic viscosity by using an equation for each cup specification number, where t is the efflux time and ν is the kinematic viscosity in centistokes. Zahn Cup #1: ν = 1.1( t − 29)