Brookfield DV2+Pro Viscometer - Manual (Page 84)

Brookfield Engineering Labs., Inc. Page 84 Manual No. M03-165-F0612
Sample Adapter, UL Adapter, Thermosel, Spiral Adapter, and DIN Adapter the accuracy value
may be increased. In general the increase in accuracy will be minimal, however, it could be as
much as 1% for a total accuracy of +/- 2% of the range in use.
Brookfield Viscosity Standards Fluids are accurate to (+/-) 1% of their stated value.
Example: Calculate the acceptable range of viscosity using RVDV-II+Pro with RV-3
Spindle at 2 RPM; Brookfield Standard Fluid 12,500 with a viscosity of 12,257
cP at 25°C:
1) Calculate full scale viscosity range using the equation:
Full Scale Viscosity Range [cP] = TK * SMC * 10,000
RPM
Where:
TK - 1.0 from Table D-2
SMC = 10 from Table D-1
Full Scale Viscosity Range 1* 10 * 10,000 = 50,000 cP
2
The viscosity is accurate to (+/-) 500 cP (which is 1% of 50,000)
2) The viscosity standard fluid is 12,257 cP. Its accuracy is (+/-)1% of 12,257 or
(+/-)122.57 cP.
3) Total allowable error is (122.57 + 500) cP = (+/-) 622.57 cP.
4) Therefore, any viscosity reading between 11,634.4 and 12,879.6 cP indicates that the Viscometer
is operating correctly. Any reading outside these limits may indicate a Viscometer problem.
Contact the Brookfield technical sales department or your local Brookfield dealer/distributor
with test results to determine the nature of the problem.
Example: Calculate the acceptable accuracy for viscosity measurement using LVDV-
II+ Pro with SC4-21 spindle in Small Sample Adapter at 6, 12, and 30 RPM.
Brookfield viscosity standard fluid 100 cPs has an actual value of 101.5 cP at
25ºC.
1) Calculate the full scale viscosity range either by using the Spindle Range Coefficient in
Appendix B of More Solutions to Sticky Problems or by using the Auto Range button on
your viscometer.
The Spindle Range Coefficient for the 21 spindle on an LV Torque instrument is 4,688.
At 6 RPM, the Full Scale Range (FSR) viscosity is 781 cP. Allow +/- 1% for the viscometer
and +/- 1% for the Small Sample Adapter. Total allowable accuracy is:
+/- 2% x 781 cP = +/- 15.6 cP
A similar calculation at 12 RPM gives FSR = 391 cP: +/- 2% x 391 cP = +/- 7.8 cP
A similar calculation at 30 RPM gives FSR = 156 cP: +/- 2% x 156 cP = +/- 3.1 cP