Brookfield KU-2 Viscometer - Manual (Page 12)

Brookfield Engineering Labs., Inc. Page 12 Manual No. M04-242-D0612
5) Wait five (5) seconds for the reading to stabilize. Switch the Hold Reading Switch to the
"DOWN" position. You will need to record measurements in KU and gm. These two
values work together to let you interpret the calibration results.
6) After you have recorded results in KU, then move the Selector knob to the "gm" position
and record your reading in grams. If you are using a printer, three measurements will be sent
to the printer and will print out as soon as the Hold Display switch is switched back to the
DOWN position.
Interpretation of Calibration Check Results
When verifying the calibration of the KU-2, the instrument tolerance and viscosity standard fluid
tolerance must be combined to calculate the total allowable error.
The KU-2 is accurate to ± 11 grams, which is 1% of the full scale range in grams. The Brookfield
Viscosity Standard is accurate to ± 1% of the stated viscosity in KU.
The total allowable error should be stated in KU. Since the instrument accuracy is stated in grams,
you will have to use the comparison table (Table A-2) and convert from grams to KU.
Correct interpretation of your calibration results requires that you compare your readings in grams to
the equivalent in KU. You must then bracket your reading with upper and lower limits based on the
allowable error of ± 11.0 grams. Convert this acceptable range in grams (as defined by the upper and
lower limits) to KU units.
Example: Calculate the allowable error of the KU-2 using fluid KU106; the stated viscosity
of the fluid is 104.8 KU. The viscometer indicated a measured viscosity of 105
KU and 410 grams.
1) Measured results from the calibration check in grams were 410 grams. Locate 410 grams on
the conversion chart (Table A-2).
2) The KU-2 is accurate to ± 11.0 grams. Starting from 410 grams, count 11 places above and
below the 410 grams. This is called "bracketing" the acceptable range. In this case, the
acceptable range will be from 399 grams to 421 grams.
3) Convert the acceptable range in grams to KU. Locate the minimum and maximum grams
bracketed. Look to the right of each number for the conversion to KU. In this case, it will be
103.9 KU minimum and 105.7 KU maximum. The total difference between 103.9 and 105.7
KU is 1.8 KU. Therefore, the accuracy is ± 0.9 KU. This is the accuracy for the Viscometer
in KU, ± 0.9 KU.