After turning on the viscometer, it is necessary to 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, and the viscous fluid is filled in between. Rotate at a steady speed, successively with the scale disc, and then drive the inner cylinder (ie, the rotor) through the hairspring and the rotary shaft to rotate. The inner cylinder (ie, the rotor) is subjected to a fluid-based viscous moment, and the greater the effect, the longer the hairspring is. The greater the torque produced by the counterbalance, the greater the scale that the pointer indicates on the dial. Multiply the reading by a specific factor to obtain the fluid's dynamic viscosity.