Brookfield DV-II+ Programmable Viscometer - Manual (Page 57)

Brookfield Engineering Labs., Inc. Page 57 Manual No. M/97-164-F1 102
4) The viscosity standard fluid, together with the spindle, should be immersed in the bath for a
minimum of 1 hour, stirring the fluid periodically (operate at 50 or 60 RPM periodically), prior
to taking measurements.
5) After 1 hour, check the temperature of the viscosity standard fluid with an accurate thermometer.
6) If the fluid is at test temperature ( + /- 0.1
°
C of the specified temperature, normally 25
°
C),
measure the viscosity and record the viscometer reading. Note: The spindle must rotate
at least five (5) times for one minute, whichever is greater before readings are taken.
7) The viscosity reading should equal the cP value on the viscosity fluid standard to within the
combined accuracies of the viscometer and the standard (as discussed in the section entitled,
Interpretation of Calibration Test Results).
Calibration Procedure for Cone/Plate Viscometers:
1) Follow the above procedures for mechanically adjusting the setting of the cone spindle to the
plate.
2) Refer to Appendix A, Table A1, and determine the correct sample volume required for the
selected spindle.
3) Select a viscosity standard fluid that will give viscosity readings between 10% and 100% of full
scale range. Refer to Appendix B for viscosity ranges of cone spindles. Consult with Brookfield
or an authorized dealer to determine which fluid is appropriate.
It is best to use a viscosity standard fluid that will be close to the maximum viscosity for a given
cone spindle/speed combination.
Example: LVDV-II + Viscometer, Cone CP-42, Fluid 10
Having a viscosity of 9.7 cP at 25
°
C
At 60 RPM, the full scale viscosity range is 10.0 cP. Thus, the Viscometer reading should be
97% torque and 9.7 cP viscosity
±
0.197 cP (0.1 cP for the viscometer plus 0.97 cP for the fluid).
The accuracy is a combination of Viscometer and fluid tolerance (refer to Interpretation of
Calibration Test Results).
4) With the viscometer stopped, remove the sample cup and place the viscosity standard fluid into
the cup, waiting 10 minutes for temperature equilibrium.
5) Connect the sample cup to the Viscometer. Allow sufficient time for temperature to reach
equilibrium. Typically 15 minutes is the maximum time that you must wait. Less time is required
if spindle and cup are already at test temperature.
6) Measure the viscosity and record the Viscometer reading in both % torque and centipoise (cP).
Notes: 1) The spindle must rotate at least five (5) times before a viscosity reading is taken.
2) The use of Brookfield Viscosity Standard fluids in the range of 5 cP to 5000 cP
is recommended for cone/plate instruments. Please contact Brookfield Engineer-
ing Laboratories or an authorized dealer if your calibration procedure requires
more viscous standards.
3) Select a viscosity standard fluid that will give viscosity readings between 10% and
100% of full scale range. Refer to Appendix B for viscosity ranges of cone
spindles. Do not use a silicone viscosity standard fluid with a viscosity value
greater than 5000 cP with a Cone/Plate Viscometer. Brookfield offers a complete
range of mineral oil viscosity standards suitable for use with Cone/Plate Viscom-
eters as shown in Table E2. Consult with Brookfield or an authorized dealer to
determine which fluid is appropriate.