Brookfield DV-I Prime - Manual (Page 52)

Brookfield Engineering Laboratories, Inc. Page 52 Manual No. M/07-022-D0613
Viscometer Related Variables
Most fluid viscosities are found to be non-Newtonian. They are dependent on Shear Rate and the spindle
geometry conditions. The specifications of the viscometer spindle and chamber geometry will affect
the viscosity readings. If one reading is taken at 2.5 rpm, and a second at 50 rpm, the two viscosity
values produced will 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 of the spindle, the size
and shape of the spindle, the size and shape of the container used and therefore, the distance between
the container wall and the spindle surface.
A repeatable viscosity test should control or specify the following:
1) Test temperature
2) Sample container size (or spindle/chamber geometry)
3) Sample volume
4) Viscometer model
5) Spindle used numbered
6) Test speed or speeds (or the shear rate)
7) Length of time or number of spindle revolutions to record viscosity
8) Presence/absence of guard leg (LV or RV models)