Principle : the viscometer rotation allows to determine the viscosity of a liquid with accuracy. for this, the device measures the mechanical resistance of a fluid which acts against the rotational movement of a cylinder.
more specifically, a cylinder or disk (spindle) that is immersed in the material to be analyzed and is rotated at a given speed. the device measures the resistance of this substance to this rotation. the resistance is the flow measurement of viscosity, depending on the speed and characteristics of the spindle; the instrument calculates the result and the direct reading of the viscosity is reflected in cp (cgs) or mpa-s (si).
the viscometers are usually equipped with different types of stems and speeds that allow you to have a wide measurement range of viscosities.