K-Patents PR-33-AC - Manual (Page 39)

7 Instrument verification 33
© Copyright K-Patents 2014. All rights reserved.
After a sample has been measured, remove the sample and clean the prism and the
sample holder. The prism can be cleaned by soft tissue and ethanol or other suitable
solvent. Repeat the procedure (cleaning, replacing the sample, measuring) for each
n
D
liquid. In case you perform the procedure more than once for a single sample, the
latest measurement will replace earlier measurements.
The table on the verification page keeps a real time record of the points measured
and the status (pass/fail) of the verification. If you have a failed point, you may either
remove it or remeasure it.
Once all liquids have been measured, the verification can be saved by clicking the Save
verification button. Please note that the button is only available after a sufficient
number of points has been measured.
The limit for acceptance is that all measurements must be within ± 0.0004 of the nom-
inal values.
Note: The refractometer verification concerns only the refractive index n
D
measure-
ment. The calculation of concentration from n
D
and process temperature TEMP is not
included, see Section 6.2, “Calibrating the concentration measurement”.
7.4 Verification report
The last saved verification data can be accessed by clicking the Verification re-
port link on the left panel. This verification report (figure 7.3) includes all measure-
ment data and the PASS/FAIL status of the verification. The report can be printed out
or saved as a reference for the quality system.
7.5 Corrective action
If the verification is not passed, first check that the prism and the sample holder are
absolutely clean and the sample holder sits tightly on the refractometer tip before a
standard liquid is applied. Make sure the standard liquids are in good condition and
not past their expiration date. Also, inspect the prism surface, checking that it is flat
and shiny without any scratches, digs or deposition on it.
Repeat the verification procedure. If the verification still fails, fill in the form Sani-
tary OEM Refractometer verification form, found in the end of this manual. You may
also print out the verification report, it carries the same information. Send the data to