| Kinematic viscosity testing using the S-flow-400 |
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Theory
The kinematic viscosity of a fluid equals its dynamic (or absolute) viscosity divided by its density. It is determined by measuring the time (in sec) required for a specified volume of liquid to flow by gravity, at a specified temperature, through a standard capillary tube (i.e. of known dimensions and volume). Kinematic viscosity is widely regarded as the most important parameter for oils and lubricants.
In practice, the measuring procedure for the S-flow-400 is very straightforward and explained below. The depicted S-flow tube shows the different steps as well:
- take a sample...
- ... inject 0.3-0.5 ml at the top of the viscometer
- ... the sample will collect in the horizontal arm of the viscometer and warms up
- ... the sample flows into the capillary
- ... as soon as the sample passes the upper mark on the viscometer, start the measurement (using a stopwatch or other timing device)
- ... when the sample passes the lower mark, stop the measurement
- ... using the constant of the viscometer tube and the measurement time, the viscosity can be easily calculated
- ... start the integrated pump by pressing the drain switch for the respective tube
- ... inject a suitable solvent in the tube to clean it and allow it to dry
- The system is ready for the next sample...
A clear white panel, which has been mounted behind the thermostatic bath, facilitates a very easy reading of the meniscus of the oil. The system, as all models, houses 4 viscometers, allowing the user to set up a range of different constants which can cover a broad spectrum of viscosities.
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