Brookfield DV-I Viscometer - Manual (Page 3)

Brookfield Engineering Laboratories, Inc. Page 3 Manual No. M/92-021-O604
I. INTRODUCTION
The Brookfield DV-I+ Viscometer measures fluid 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-I+.
The principle of operation of the DV-I+ 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 measurement
range of a DV-I+ (in centipoise or milliPascal seconds) 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.
There are four basic spring torque series offered by Brookfield:
Spring Torque
Model dyne-cm milli Newton-m
LVDV-I + 673.7 0.0673
RVDV-I + 7,187.0 0.7187
HADV-I + 14,374.0 1.4374
HBDV-I + 57,496.0 5.7496
The higher the torque calibration, the higher the measurement range. The viscosity measurement
range for each torque calibration may be found in Appendix B.
All units of measurement are displayed according to either the CGS system or the SI sys-
tem.
1. Viscosity appears in units of centipoise (shown as “cP”) or milliPascal-seconds (shown as
mPa•s) on the DV-I+ Viscometer display.
2. Torque appears in units of dyne-centimeters or Newton-meters (shown as percent “%”) in
both cases) on the DV-I+ Viscometer display.
The equivalent units of measurement in the SI system are calculated using the following conver-
sions:
SI CGS
Viscosity: 1 mPa•s = 1 cP
Torque: 1 Newton-m = 10 7 dyne-cm
References to viscosity throughout this manual are done in CGS units. The DV-I+ Viscometer
provides equivalent information in SI units.