



The viscosity measured by the COAT-4 viscometer is the conditional viscosity, that is, the time for a certain amount of sample to flow out of the hole with a specified pore size at a certain temperature, expressed in seconds. The resulting specimen elution time (s) is converted into kinematic viscosity values (mm²/s) using the following formula:
At t<23s, t=0.154μ+11
At 23s≤t≤150s, t=0.223μ+6.0
where:
t— outflow time, s;
μ – kinematic viscosity, mm²/s.
1. The Tu-4 viscometer is made of brass, with a capacity of about 100 ml, and its geometric size and inner wall roughness conform to the provisions of GB/T 1723 Coating Viscosity Determination Method, and its bottom is an outflow hole of stainless steel.
2. Correction coefficient K: multiply the viscosity measured by the corrected viscometer by the K value, which is the conditional viscosity measured by the viscometer. The correction factor K should be in the range of 1±0.03, otherwise the viscometer should be replaced. The viscometer should be calibrated regularly according to the frequency of its use.
3. The difference between the measured value and the calculated value of the standard viscosity liquid with known kinematic viscosity from the Tu-4 viscometer should be within ±3% of the calculated value.