Brookfield DV-III Ultra Rheometer - Manual (Page 5)

Brookfield Engineering Laboratories, Inc. Page 5 Manual No. M/98-211-B0104
Brookfield Engineering Laboratories, Inc. Page 5 Manual No. M98-211-E0912
The Brookfield DV-III Ultra Programmable Rheometer measures fluid parameters of Shear Stress
and Viscosity at given Shear Rates. Viscosity is a measure of a fluid’s resistance to flow. You will
find a detailed description of the mathematics of viscosity in the Brookfield publication “More
Solutions to Sticky Problems”, a copy of which was included with your DV-III Ultra.
The principle of operation of the DV-III Ultra is to drive a spindle (which is immersed in the test
fluid) through a calibrated spring. The viscous drag of the fluid against the spindle is measured
by the spring deflection. Spring deflection is measured with a rotary transducer. The viscosity
measurement range of the DV-III Ultra (in centipoise or cP) is determined by the rotational speed
of the spindle, the size and shape of the spindle, the container the spindle is rotating in, and the full
scale torque of the calibrated spring.
The DV-III Ultra can also measure yield stress (in Pascals or Pa). See Section I.3 for more information
on yield stress.
I.1 Torque Measurement
There are four basic spring torque models offered by Brookfield:
Spring Torque
Model dyne•cm mN•m
LVDV-III Ultra 673.7 0.0673
RVDV-III Ultra 7,187.0 0.7187
HADV-III Ultra 14,374.0 1.4374
HBDV-III Ultra 57,496.0 5.7496
The higher the torque calibration, the higher the viscosity measurement range. The viscosity
measurement range for each spring torque model may be found in Appendix B.
I.2 Viscosity Units of Measurement
All units of measurement are displayed according to either the CGS system or the SI
system.
1. Viscosity appears in units of centipoise (shown as “cP”) or milliPascal-seconds (shown
as mPa•s).
2. Shear Stress appears in units of dynes/square centimeter (“D/cm 2 ”) or Newtons/square
meter (“N/m 2 ”).
3. Shear Rate appears in units of reciprocal seconds (“1/SEC”).
4. Torque appears in units of dyne-centimeters or Newton-meters (shown as percent “%”
in both cases).
The equivalent units of measurement in the SI system are calculated using the following
conversions:
SI CGS
Viscosity: 1 mPa•s = 1 cP
Shear Stress: 1 Newton/m 2 = 10 dyne/cm 2
Torque: 1 N•m = 10 7 dyne•cm
References to viscosity throughout this manual are done in CGS units.
I. INTRODUCTION