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Calibration procedure using Helipath Stand and T-Bar spindles
When a Helipath Stand and T-Bar spindles are used:
•
Remove the T-bar spindle and select a standard LV (#1-3) or RV, HA, HB (#1-6) spindle. Follow the
procedures for LV (#1-3) and RV, HA, HB (#1-6) AMETEK Brookfield spindles outlined above.
•
T-Bar spindles should not be used for verifying calibration of the DVNext Rheometer.
Calibration procedure for Spiral Adapter
AMETEK Brookfield recommends a two-step check. First, verify the calibration of the rheometer using the standard
rheometer spindles (LV #1-3, RV #2-6, HA #2-6 and HB #2-6 or cone/plate spindles) as detailed in this appendix.
Second, verify the calibration of the rheometer using the Spiral Adapter. The use of an accessory device may
increase the accuracy of measurement associated with the DVNext.
•
Place the viscosity standard fluid (in the proper container) into the water bath (refer to the Spiral Adapter
instruction manual).
•
Attach the spindle to the rheometer. Attach chamber (SA-1Y) and clamp to the rheometer.
•
Lower the DVNext into measurement position. Operate the rheometer at 50 or 60 RPM until the chamber
is fully flooded.
•
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.
•
After 1 hour, check the temperature of the viscosity standard fluid with an accurate thermometer.
•
If the fluid is at test temperature (+/- 0.1°C of the specified temperature, normally 25°C), measure the
viscosity and record the rheometer reading. Note: The spindle must rotate at least five (5) times or for one
minute, whichever is greater before readings are taken.
•
The viscosity reading should equal the cP value on the viscosity fluid standard to within the combined
accuracies of the rheometer and the standard (as discussed in the section entitled, Interpretation of
Calibration Test Results). However, instrument accuracy is ±2% of the maximum viscosity range and not
the standard 1%.
Calibration procedure for Cone/Plate Rheometers
•
Follow the above procedures for mechanically adjusting the setting of the cone spindle to the plate.
•
Refer to Appendix A; Table A-1 and determine the correct sample volume required for the selected spindle.
•
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 AMETEK 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: DVNext LV Rheometer, 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 Rheometer reading should be 97%
torque and 9.7 cP viscosity ± 0.197 cP (0.1 cP for the rheometer plus 0.097 cP for the fluid). The
accuracy is a combination of Rheometer and fluid tolerance (refer to Interpretation of Calibration Test
Results).
•
With the rheometer stopped, remove the sample cup and place the viscosity standard fluid into the cup,
waiting 10 minutes for temperature equilibrium.
•
Connect the sample cup to the Rheometer. Allow enough 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.
•
Measure the viscosity and record the Rheometer reading in both % torque and centipoise (cP).
M19-2101 REVISION 2.0
D V N E X T R H E O M E T E R - O P E R AT I O N A L M A N U A L
108
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