(1) Cleaning and drying
For viscometers that have been stored for a long time, newly purchased or used for oil testing, they must be soaked in chromic acid lotion for 2 hours before use, then degreased with gasoline and ethanol, cooled with water, and then soaked in chromic acid lotion for more than 4 hours. Finally, rinse with water and therapeutic water until no water drops hang on the inner wall.
Place the cleaned viscometer in an oven at 105°C to dry, and prevent it from falling into dust.
(2) Precautions for use
Keep it vertical. The viscometer should be fixed vertically in the constant temperature precision, because the liquid level difference will change when it is tilted, which will cause measurement errors.
temperature control. The temperature change is generally required not to exceed ±0.5°C, and the viscometer should be calibrated before starting to measure after placing the viscometer in a warming solution for 15 minutes.
Eliminate air bubbles. After liquid filling, if there are air bubbles in the viscometer, wait for the air bubbles to completely disappear before measuring; when pumping liquid, control the pumping speed, and if the liquid is pumped too fast, air bubbles will also be generated.
Measuring timing. Record the time when the lowest point of the liquid meniscus is tangent to the scale line. One time injection can repeat determination ls
Data, take its arithmetic mean. For each viscometer, two standard liquids shall be selected to measure the viscometer constant, and the arithmetic mean value shall be taken.
(3) Selection of viscometer
The choice of a viscometer should be based on the characteristics of the liquid, the viscosity range, the required outflow time, and the requirements for viscosity accuracy. For example, if the viscosity of the liquid is around 10cSt, when it is required that the l division is above 120s when the outflow is required, the viscometer with a constant of 0.3℃s, /s is selected as Xuan. Pinners and Oswald viscometers are the more convenient types of viscometers that are commonly used. If it is an opaque liquid, it is more appropriate to use a countercurrent viscometer; when the viscosity accuracy is required to be high, use an Ubbelohde viscometer; Viscometer.
When processing viscous juice, it is necessary to strictly select materials. For example, the glass should be colorless and transparent, and there should be no nodes, air bubbles and watermarks at the measuring ball and capillary.
