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A viscometer is a physical analysis instrument for measuring fluid viscosity. Viscosity is a physical property of fluid substances, which reflects the internal friction between molecules when the fluid is subjected to external force. The viscosity of a substance is closely related to its chemical composition. In industrial production and scientific research, it is often used to monitor the composition or quality of substances by measuring viscosity. For example, in the production process of polymer materials, the application of viscometer can monitor the viscosity of the synthetic reaction product and automatically control the reaction end point. Others such as oil cracking, lubricating oil blending, automatic control of production processes of certain foods and medicines, monitoring of crude oil pipeline transportation, quality inspection of various petroleum products and paints, etc., all require viscosity measurement.

Classification

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 type of viscometer. Its working principle is: the sample container (including the outflow capillary) is filled with the sample to be tested, and is 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. Its main viscometer should include 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 sample under test: 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.

By type of measurement product:

Solder paste viscometer: The solder paste viscometer adopts a coaxial double cylinder rotary viscometer with a screw pump sensor, which is mainly used to measure solder paste, film thickness paste, adhesive, solder paste solder resist, liquid resist Solder paint, other inks, pastes, etc. According to the tightness of the measuring part, it has temperature adjustment skills, and it can be connected to a personal computer for automatic measurement and automatic calculation of data reading.

Portable viscometer: The portable viscometer adopts the coaxial double cylinder type, the spiral line sliding method pump sensor maintains a fixed flow, and can accurately measure the viscosity of the sticky body according to the viscosity change of the connection and stirring.

Viscosity controller: The viscosity controller can well manage the viscosity of various fluids such as coatings, inks, adhesives, food, medicines, oils, etc. A steady flow can be obtained, and a stable value can be obtained; the viscosity of a viscous body that continuously changes according to the stirring viscosity can be accurately measured.

Stormer Viscometer: The Stormer viscometer is a test instrument used to determine the viscosity of paints and other coatings with a KU value. The design of the instrument follows the ASTM standard and the GB9269-88 standard. Tianjin Jingke Material Testing Machine Factory is the largest enterprise specializing in the production of paint, coating, ink equipment material testing machines and special equipment for the coating industry laboratory. The viscometer adopts a single-chip microcomputer, and the operator can directly read the KU value of the measured sample from the instrument without looking up the table.

Working principle: Immerse the paddle rotor into the sample to be tested, increase or decrease the weight of the weight to keep the speed of the paddle rotor at 200 rpm, input the weight of the sample to be tested at 200 rpm through a single-chip microcomputer Replaced with viscosity KU value.