The viscosity measured by the Tu-4 viscometer is the conditional viscosity, which is the time for a certain amount of sample to flow out of a hole with a specified aperture at a certain temperature, expressed in seconds. Convert the obtained sample outflow time (s) into kinematic viscosity value (㎜²/s) with the following formula:
When t<23s, t=0.154μ+11
When 23s≤t≤150s, t=0.223μ+6.0
In the formula:
t——outflow time, s;
μ—kinematic viscosity, mm²/s.
1. The Tu-4 viscometer is made of brass, with a capacity of about 100ml. Its geometric dimensions and inner wall roughness meet the requirements of "GB/T 1723 Method for Determination of Viscosity of Paint". The bottom is a stainless steel outflow hole.
2. Correction coefficient K: Multiply the viscosity measured by the calibrated viscometer by the K value, which is the conditional viscosity measured by the viscometer. The correction coefficient K should be within the range of 1±0.03, otherwise the viscometer should be replaced. The viscometer should be calibrated periodically according to the frequency of its use.
3. The difference between the measured value and the calculated value of the outflow time of the standard viscosity liquid with known kinematic viscosity from the Tu-4 viscometer should be within ±3% of the calculated value.