Lubricants
What are they?
Viscosity is a measure of a fluid’s resistance to shearing flow and describes the internal friction of a moving fluid.
The Brookfield Viscometer measures the dynamic viscosity of a fluid, which is the viscosity determined under shearing conditions.
The Anton Paar Stabinger Viscometer measures the dynamic viscosity (DV) and density of a fluid (ρ) and then uses these values to calculate the Kinematic Viscosity (KV), where KV = DV/ ρ and is defined as as the viscosity of a fluid as it flows under gravity.
Why do we use it?
Viscosity is the single most important characteristic by which automotive and industrial lubricants are categorised and designed. It is never the only characteristic that is considered, but is most often the starting point when formulating a lubricant.
The International Standard Organisation (ISO) Grade of a lubricant is determined by a measurement of the kinematic viscosity at 40°C ± 10%.
The Viscosity Index (VI) is important for both industrial and automotive applications. VI is an arbitrary measure for the change of viscosity with variations in temperature. It is calculated using the values of the KV at 40°C and the KV at 100°C. The smaller the change in viscosity over the temperature range, the higher the viscosity index.
How does it work?
The Brookfield Viscometer rotates a conical spindle at a precise speed and measures the torque needed to overcome the viscous resistance to the induced movement caused by the presence of sample fluid between the spindle and sample container.
The Stabinger Viscometer is a rotational viscometer with cylinder geometry. It contains a rapidly rotating outer tube and an inner measuring bob which rotates more slowly. This allows the dynamic viscosity to be measured.
Simultaneously the density is measured using the oscillating U-tube principle.
Test Capabilities:
Brookfield Viscometer - (by using a Small Sample Adapter, the viscosity can be extremely accurate measured)
Parameter : Measuring Range
- Dynamic Viscosity : 50 to 3,300,000 mPa.s
- Temperature : Ambient to 100ºC
- Test Methods : Internal methods
Anton Paar Stabinger Viscometer -
Parameter : Measuring Range
- Kinematic Viscosity : 0.2 to 30,000 mm2/s
- Temperature : -60 to 135ºC
- Density : 0.6 to 3 g/cm3
- Test Methods : ASTM D4052 | ASTM D7402
The Brookfield Viscometer:
The Anton Paar Stabinger Viscometer: