Brookfield CAP2000 Viscometer - Manual (Page 30)

Brookfield Engineering Labs., Inc. Page 30 Manual No. M02-313-G0812
Viscometer Related Variables
• Most fluid viscosities are found to be non-Newtonian. They are dependent on shear rate and
the spindle geometry. The specifications of the Viscometer cone and plate geometry will affect
the viscosity readings. For example, if one reading is taken at 750 rpm, and a second at 900
rpm, the two viscosity values may be different because the readings were made at different
shear rates. The faster the spindle speed, the higher the shear rate.
• The shear rate of a given measurement is determined by the rotational speed and the cone
angle.
• A repeatable viscosity test should control or specify the following:
1. Viscometer model
2. Cone Spindle used: Cone Angle and Cone Diameter
3. Test temperature
4. Cone Spindle speed [or the shear rate]
5. Length of time to rotate cone spindle before recording the viscosity reading
6. Sample volume sufficient to cover the face of the cone
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