| Kinematic viscosity testing using (page 1/2) |
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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-850 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
- ... the sample passes the first optical sensor, the measurement begins
- ... the sample passes the second sensor, the measurement ends
- ... if a printer is present, the result is printed out, otherwise presented on-screen
- ... the user presses the "drain" button, which starts the integrated pump
- ... the user injects a suitable solvent in the tube and allows it to dry
- The system is ready for the next sample...
Note after step 2, operator attendance is no longer required : the system will perform the measurement automatically and print out or store the result. The user can then start the integrated pump, which will drain the sample from the tube. A suitable solvent can be manually (e.g. using a washing bottle)injected.
Since the sample is injected from the top of the viscometer, it passes the optical sensor only once, thereby making it suitable for both transparant and opaque samples.
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