Viscometer daily use precautions

First, the performance indicators of the viscometer must meet the requirements of the national metrological verification regulations. The instrument in use must undergo periodic verification. When necessary (instrument is used frequently or in a critical state of qualification), an intermediate self-check is required to determine its metrological performance. The coefficient error is within the allowable range. Otherwise, accurate data cannot be obtained.

Second, the viscometer pays special attention to the temperature of the liquid being measured. Many users neglect this point and think that the temperature difference does not matter. Our experiments have proved that when the temperature deviation is 0.5°C, the viscosity of some liquids deviates by more than 5%. The temperature deviation has great influence on the viscosity, and the temperature rises and the viscosity decreases. Therefore, special attention should be paid to keeping the temperature of the measured liquid constant near the specified temperature point, and it is better not to exceed 0.1°C for accurate measurement.

Third, the viscometer measurement container (outer tube) selection. For double-barrel viscometers, read the instrument manual carefully. Different rotors (inner cylinders) are matched to the corresponding cylinders. Otherwise, the measurement results will be greatly biased. For a single cylinder rotary viscometer, the radius of the outer cylinder is in principle required to be infinitely large. The actual measurement requires that the inner diameter of the outer cylinder, that is, the measurement container, be not less than a certain size.

Fourth, the correct choice of rotor or adjust the speed, so that the value between 20 to 90 grid. This type of instrument uses a dial plus pointer readings, its stability and reading bias combined together have 0.5 grids, if the reading is too small as near 5 grid, the relative error caused by more than 10%, if you choose the right rotor or speed With a reading of 50 cells, the relative error can be reduced to 1%. If the value is more than 90, the torque generated by the hairspring is too large, creep easily occurs, and the hairspring is damaged. Therefore, the rotor and the rotation speed must be properly selected.

Fifth, viscometer frequency correction. For nominal frequency of domestic instruments at 50Hz, and China's current power supply frequency is also 50Hz, we use the frequency meter to test the variability less than 0.5%, so the general measurement does not require frequency correction. However, for some instruments in Japan and Europe and America, the nominal frequency is 60Hz, and the frequency must be corrected. Otherwise it will produce 20% error. The correction formula is: actual viscosity = indicated viscosity × nominal frequency ÷ actual frequency VI, viscometer rotor immersed in liquid Depth and bubble effects. The rotational viscometer has strict requirements on the depth of the rotor immersed in the liquid and must be in accordance with the requirements of the specification (some binocular instruments have strict requirements on the amount of liquid used for the test and must be taken from the measuring cylinder). When the rotor is immersed in the liquid, bubbles are often present. Most of the float will disappear after the rotor rotates. The bubbles attached to the lower part of the rotor sometimes cannot be eliminated. The presence of bubbles will cause a large deviation in the measurement data, so tilting Slowly immersing the rotor is an effective way.

Seven, viscometer rotor cleaning. The measuring rotor (including the outer cylinder) is to be clean and free from dirt. It is usually cleaned after the measurement, especially after the paint and adhesive are measured. Pay attention to the cleaning method, soaking with a suitable organic solvent, do not use a metal knife and other hard scraping, because the rotor surface has serious scratches will bring about the deviation of the measurement results.

Eight, viscometer other issues that need attention. 1. Most instruments need to adjust the level. After leveling the rotor and adjusting the height of the rotor and during the measurement process, pay attention to the level problem at any time, otherwise it will cause the reading to be misaligned or even impossible to read. 2. Some instruments need to be equipped with protective frames. Read the instructions carefully to install according to the regulations, otherwise it will cause reading deviation. 3. Determine whether it is an approximate Newtonian fluid. For non-Newtonian fluids, select the rotor, rotation speed, and rotation time after selection to avoid misunderstanding as instrument inaccuracy. In summary, although the rotary viscometer has a simple structure and is easy to use, if it is used incorrectly, a properly qualified instrument cannot obtain accurate measurement results and affect the product quality.

The above is the precautions for everyday use of viscometers provided by Xiao Bian. We can make some references based on these contents. We hope to help users learn some of the maintenance knowledge of viscometers properly. Through the above brief description, users learn more about viscometer knowledge can help the user to solve some small problems in the future use process. Routine maintenance and maintenance of the viscometer can improve the performance of the viscometer, reduce the failure of the instrument, and avoid affecting the normal operation of the entire production system, resulting in huge economic losses.