Kinematic viscosity

Principle: At a constant temperature, measure the time for a certain volume of liquid to flow through a calibrated glass capillary viscometer under gravity. The product of the capillary constant of the viscometer and the flow time is the kinematic viscosity of the measured liquid at that temperature.

step

1. To adjust the viscometer to a vertical position, use a plumb line to check the verticality of the capillary tube in two mutually perpendicular directions. Adjust the constant temperature bath to the specified temperature and immerse the viscometer with the sample in the constant temperature bath for 10-15 minutes.

2. Use the rubber tube covered by the capillary viscometer tube to suck the sample into the expanding part with a suction ball, so that the liquid level of the sample is slightly higher than the upper marking line, and be careful not to cause bubbles in the liquid in the capillary and expanding part.

3. Release the suction ball and record the time the liquid level flows through the marking.

4. The flow time recorded with a stopwatch should be repeated at least four times, and the difference between each flow time and its arithmetic mean should not exceed ± 0.5% of the arithmetic mean.

Calculation: The kinematic viscosity of the sample at temperature t

Where vt is the kinematic viscosity, m2/s; C is the viscometer constant, m/s; τ T is the average flow time of the sample, s.

Take the arithmetic mean of two repeated measurements as the kinematic viscosity of the sample.