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Viscometer is a physical analysis instrument for measuring fluid viscosity, which can monitor the viscosity of synthetic reaction products and automatically control the reaction end point. There are many types of viscometers, and the classification methods are also different. Today, Xiaobian will introduce the classification of viscometers in detail, hoping to help everyone.

According to the working mode, there are three types: capillary type, rotary type and vibration type.

According to the working mode: offline viscometer (sampling detection), online viscometer (24-hour continuous measurement), portable viscometer

Capillary Viscometer: A capillary viscometer is usually a Saybolt viscometer, which is a common viscometer. The working principle is as follows: the sample container (including the outflow capillary) is filled with the sample to be tested, in a constant temperature bath, and the height of the liquid column is h. Open the cock, the sample begins to flow to the liquid receiver, and the time is calculated until the sample liquid level reaches the mark. The more viscous the sample, the longer this period of time. Therefore, this time directly reflects the viscosity of the sample.

Rotational Viscometer: A common rotational viscometer is the cone and plate viscometer. It mainly includes a flat plate and a cone plate. The motor drives the plate to rotate at a constant speed through the variable speed gear, and the sample to be tested is kept between the two plates by capillary action, and the friction between the sample molecules drives the cone to rotate. Under the action of the torsion spring in the torque detector, the cone and plate will not rotate after rotating a certain angle. At this time, the torque exerted by the torsion spring is related to the internal molecular friction (ie viscosity) of the tested sample: the greater the viscosity of the sample, the greater the torque. There is a variable capacitor in the torque detector, and its moving piece rotates with the cone and plate, thereby changing its own capacitance value. The torsion spring torque reflected by this capacitance change is the viscosity of the tested sample, which is displayed by the meter.

Rotational viscometer has the advantages of convenient use, stable performance, simple maintenance, etc. It is suitable for measuring various oils, paints, inks, coatings, plastics, slurries, rubber, latex, detergents, resins, condensed milk, cream, drugs, and cosmetics. It is an essential instrument for laboratories and analysis rooms in textile, chemical, petroleum, electromechanical, pharmaceutical, food, light industry, construction and other industries, as well as universities, research institutes, and military departments.

After the rotary viscometer is turned on, it must first detect the zero position. This operation is generally carried out without installing the rotor. Then, the inner cylinder of radius R2 is coaxially installed in the outer cylinder of radius R1, which is filled with viscous fluid. The synchronous motor Rotate at a stable speed, connect the dials one after another, and then drive the inner cylinder (that is, the rotor) to rotate through the hairspring and the rotating shaft. The inner cylinder (that is, the rotor) is affected by the fluid-based viscous moment. The greater the torque generated by the counterbalance, the larger the scale indicated by the pointer on the dial. Multiply the reading by a specific factor to get the dynamic viscosity of the liquid.

Vibration viscometer: The working principle of this viscometer is that when the object in the fluid vibrates, it will be hindered by the fluid, and the magnitude of this effect is related to the viscosity of the fluid. Commonly used vibrating viscometers are ultrasonic viscometers, which have a shrapnel in the detector. When excited by a pulsed current, the shrapnel produces mechanical vibrations in the ultrasonic range. When the shrapnel is immersed in the sample to be tested, the amplitude of the shrapnel is related to the viscosity and density of the sample. With a known density, the viscosity value can be derived from the measured amplitude data.