DVS+ measures viscosity in a wide range. For example, DVSRV can test fluids in the range of 100-13,000,000cP by using different rotors and different speeds. This range can be achieved by using different rotors and various speeds.
For an unknown fluid, the process of selecting a rotor and speed is often a process of trial and error. Proper selection can make the % torque range of the instrument between 10-100. There are two general rules in this trial and error process:
1) The viscosity range is inversely proportional to the size of the rotor.
2) The viscosity range is inversely proportional to the rotation speed.
In other words, to test high viscosity, choose a small spindle and/or low speed. If the selected spindle/speed results in a reading above 100%, the speed will need to be reduced or a smaller spindle selected.
When the test proves that several rotor/speed combinations can obtain satisfactory results between 10-100%, in this case, any one of these rotors can be selected.
Viscosities measured for non-Newtonian fluids will vary with changes in spindle and/or speed.
To compare viscosity data, you need to make sure that the same test method is used. That is: use the same instrument, rotor, speed, container, temperature, and test time.
