Calibration method of Tu-4 viscosity cup

(1) Kinematic Viscosity Method     This method is based on the national standard "GB265 Kinematic Viscosity Determination Method", using a capillary viscometer to measure the kinematic viscosity of various standard oils. (25±0.2)°C], use various standard oils with known kinematic viscosity, and measure the outflow time t of the viscometer being calibrated according to the method of dividing by 4 cups.

According to the kinematic viscosity of the standard oil, the standard outflow time T of the Tu-4 cup is calculated by the formula

T represents the standard outflow time (s), V represents the kinematic viscosity (mm ² /s)

Under the same conditions, the ratio of the standard outflow time T of the viscometer being calibrated to the measured outflow time t is the correction coefficient K of the Viscosity Cup, and the formula is

K = T  / t

K represents the correction coefficient of the viscometer, T represents the standard outflow time, and t is the measured outflow time

Obtain a series of correction coefficients K1, K2, K3, etc. according to the above formula, and take the arithmetic average value, which is the correction coefficient K of the Viscosity Cup. If K is within the range of 0.95~1.05, the Viscosity Cup is qualified and still It can be used, but the test data should be multiplied by the correction coefficient K, which is the real measured viscosity.

(2) Standard viscometer method     The standard Viscosity Cup is commonly called the K value cup, and the standard load cup is used to calibrate the Tu-4 cup used regularly. The calibration method is the same as that of the Tu-1 cup.

(3) Engua condition degree method     Engua condition degree refers to the ratio of the time required for the sample to flow out of 200mL from the Engel viscometer at a certain temperature to the time in seconds (s) required for distilled water to flow out of the same volume at 20°C. The standard water value of Engua viscometer should be (51±l)s.

Calculate the conditional degree ('E) of each standard oil by using the Engela viscometer, find out the kinematic viscosity according to the corresponding table, and calculate T by formula (1) or formula (2), which is the same as the outflow time measured by the calibrated Viscosity Cup The ratio of t is the correction coefficient K. As the viscosity of the standard oil increases, the data deviation of this method gradually increases, so it is rarely used at present.