All fluids have an internal friction between molecules, which determines how well fluid flows. Viscosity is perceived as 'thickness' or resistance to pouring, but there is more to viscosity than this.
#Viscosity testing pro#
This allows for better engine performance and lifetime.Ī 5W-30 motor oil was tested using a Brookfield LV-II+ Pro Viscometer. Some oils are given two ratings, such as 5W-30, to indicate oil that has been treated with additives to flow like SAE 5 oil at start-up but SAE 30 after the engine reaches operating temperature.
To facilitate this, oils are classified based on their viscosity and given a certification grade, such as 5, 10, 20, 30 40, or 50 these grades are defined by the Society of Automotive Engineers (SAE). This requires that the correct viscosity oil be used. However, if oil viscosity is too high, the oil may not pump properly during start-up when the engine is still cold. If the oil viscosity is too low, the lubrication layer between parts will be too thin to prevent engine parts from grinding against each other. Motor oil viscosity is an important consideration for improving the performance and extending the lifetime of any engine. Typical Newtonian fluids are water and thin lubricating oils. Mathematically, it is expressed as Equation 1.įluids that behave according to Equation 1 are called Newtonian. He assumed that the shear stress, τ, required to cause the difference in velocity was proportional to the change in velocity across dx, or the velocity gradient. Newton defined viscosity, μ, by considering a situation like Figure 1 where two parallel planes of fluid of equal area, A, are separated by a distance, dx, and traveling at different velocities, V 1 and V 2. When a shear force is applied, it must overcome the intermolecular forces in order to move the liquid. The internal friction arises from attractive forces between the molecules of the fluid. Shear forces can occur during operations such as pouring, mixing, spreading, or spraying. A large viscosity will require a large shear force to overcome the internal friction. Viscosity is a useful fluid parameter used to describe a fluid’s internal friction or resistance to motion. Viscosity of Motor Oil as a Function of Temperature
Instrument Key Specifications Temperature Range
Instrument: Brookfield LVDV-II+P Viscometer
#Viscosity testing pdf#
Viscosity of Motor Oil as a Function of Temperature, PDF Any operation that involves movement of a fluid, such as pumping, mixing, spreading, pouring or spraying, can be better defined by understanding the flow behavior of the fluids involved.įor more information please read our application notes. Contact Stylus Surface Roughness AnalysisĮxpress Property Mapping through Accelerated NanoindentationĪlloy Composition and Phase Identification
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