PT-8S Digital Rotational Viscometer Features: 1. This instrument is a digital viscometer, where the motor drives the rotor at a constant speed via a speed reducer. When the rotor rotates in the liquid, the liquid generates a viscous torque acting on the rotor—the greater the viscosity of the liquid, the larger this viscous torque becomes; conversely, the smaller the viscosity of the liquid, the smaller the viscous torque. The viscous torque acting on the rotor is detected by