Why do you need to verify?
Statutory inspection, user routine inspection.
The Rotational Viscometer uses a beryllium-copper alloy spring and the corresponding supporting mechanism to complete the operation of the principle of the rotational torque of the rotor in the liquid. The twist degree of the spring measured by the sensor is proportional to the viscosity of the liquid. However, these memory metals will also fatigue over time , which will change the measurement state of the instrument, so inspection is needed.
purpose of verification
Check the degree of deviation of the Rotational Viscometer from the normal value to judge the degree of wear of the Rotational Viscometer. This calibration is of the nature of inspection and cannot be adjusted by the user, which is different from the calibration of an electronic balance.
Standards used
Viscosity standard products that meet the NIST standards of the United States can be provided, which are divided into two categories: normal temperature standard products and high temperature standard products. The nominal viscosity values of commonly used normal temperature standard products at room temperature (25C) are: 1000, 5000, 12500, 30000, 60000, 100000. Its specific gravity is between 0.92-1.00, and there is a correction value between the actual viscosity and the nominal value of each standard, so the actual viscosity is near the nominal viscosity, which has been indicated on the label.
The selection principle of the standard is to choose the viscosity standard closest to the viscosity of the sample to be measured.
When using standard products, care should be taken to avoid possible dilution and contamination of standard products, and it is better not to reuse them. Cover and .
Viscosity is a physical quantity parameter that is very sensitive to temperature. Small changes in temperature may cause considerable deviations in viscosity. Therefore, it is very important to keep the temperature stable during viscosity measurement, especially during calibration. Therefore, it is necessary to use a constant temperature circulating Water Bath of.
Calibration operating procedures
1. Preparation of constant temperature conditions for the viscosity measurement container;
2. Select the combination of rotor and speed according to the operating procedures of the instrument. Each combination of rotor and speed forms a full scale range (measurement range); the principle of combination selection is to make the viscosity of the standard product within 50% of the full scale. %, the range less than 10% of full scale and greater than 90% is inappropriate. It is worth noting that although the combination of a large rotor (small rotor) at low speed and the use of a small rotor (large No.) combined with high rotation speed can get approximately the same measurement range, but in order to avoid eddy current at high speed and make the measurement results unstable and reduce the wear and tear of the instrument, the combination of small rotor and low speed should be selected as much as possible.
1. Determine the standard product according to the conventional measurement method, and read the viscosity data.
2. Judge the stability, reproducibility and value of the data.
Criteria for judging the status of the instrument
Generally, with a new instrument or a well-adjusted viscometer, at a constant temperature (25C), the measured value obtained by selecting a suitable combination of rotor and rotational speed should be equivalent to the nominal value, and the error should be within 2%. If the error is greater than ±10%, the viscometer cannot be used and needs to be repaired or adjusted.
