Brookfield CP-51 - Interpreting Calibration Results

Brookeld Engineering Laboratories, Inc. Page 22 Manual No. M00-151-I0614
7) e viscosity reading should equal the cP value on the viscosity uid standard to within the
combined accuracies of the viscometer and the standard (as discussed in the section entitled,
Interpretation of Calibration Test Results). However, instrument accuracy is ±/- of the maximum
viscosity range and not the standard 1%.
Interpretation of Calibration Test Results:
When verifying the calibration of the Viscometer, the instrument and viscosity standard uid error must
be combined to calculate the total allowable error.
e Dial Viscometer is accurate to ± 1% of any full scale spindle/speed viscosity range.
Brookeld Viscosity Standard Fluids are accurate to ± 1% of their stated value.
Example: Calculate the acceptable range of viscosity using RVT with RV-3 Spindle at 2 RPM;
Brookeld Standard Fluid 12,500 with a viscosity of 12,257 cP at 25°C:
1) Refer to the instructions on the FACTOR FINDER. Calculate the full scale viscosity range by
multiplying the spindle/speed FACTOR by 100.
Spindle RV-3, 2 RPM FACTOR = 500
Full scale viscosity range is 500 x 100 = 50,000 cP
e viscosity is accurate to ± 500 cP (which is 1% of 50,000)
Note: All spindle/speed factors found on the FACTOR FINDER are equivalent to 1% of the
spindle/speed full scale viscosity range.
2) e viscosity standard uid 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) erefore, 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 Brookeld technical sales department or your local Brookeld dealer/distributor
with test results to determine the nature of the problem.
Note: Excel Spreadsheet template is available on our website for analyzing calibration
results.