Viscometer Classification

There are many types of viscometers. The commonly used are capillary viscometer, rotary viscometer and vibration viscometer.

Capillary viscometer

Capillary viscometer is usually a Saybolt viscometer, which is a common viscometer. Its working principle is: 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 receiver, and at the same time, the time is calculated until the sample liquid level reaches the scale line. The sample viscosity is greater, and this period is longer. Therefore, this time directly reflects the viscosity of the sample.

Rotating viscometer)

A common digital rotational viscometer is a cone-plate viscometer. It mainly includes a flat plate and a cone plate. The motor drives the plate to rotate at a constant speed through a variable speed gear. The capillary action is used to keep the sample being measured between the two plates, and the friction between the sample molecules drives the cone and plate to rotate. Under the action of the torsion spring in the torque detector, the cone plate no longer rotates after rotating a certain angle. At this time, the torque applied by the torsion spring is related to the internal friction (ie, viscosity) of the molecules of the sample being measured: the sample viscosity is greater ,and the torque is greater. There is a variable capacitor in the torque detector, and its moving piece rotates with the cone plate, thereby changing its own capacitance value. The torque of the torsion spring reflected by this change in capacitance is the viscosity of the measured sample, which is displayed by the meter.

Vibration viscometer

The working principle of this kind of viscometer is: the object in the fluid will be hindered by the fluid when it vibrates. The magnitude of this effect is related to the viscosity of the fluid. Commonly used vibrating viscometers include ultrasonic viscometers. There is a shrapnel in its detector. When excited by a pulsed current, the shrapnel generates mechanical vibration in the ultrasonic range. When the shrapnel is immersed in the tested sample, the amplitude of the shrapnel is related to the viscosity and density of the sample. When the density is known, the viscosity value can be obtained from the measured amplitude data.