Taylor K-8000, User Manual, Page: 47 / 100

3-21 TTi
®
Colorimeter User’s Manual
Part 3 Colorimeter Operation
To edit the timer:
Edit Timer using  ,  ; then press ENTER .
The upper limit of the timer is 99:59 minutes.
Footer Option: OK
Saves changes and returns to TIMER screen.
ADJUST CALIBRATION
The Adjust Calibration option can be used to adjust preprogrammed calibrations when required by regulations,
quality control protocol, or in rare circumstances where all samples show a consistent bias. This option is
allowed for most, but not all, preprogrammed tests and there is a limit to the allowed adjustment. This option
is not available for absorbance and transmittance tests.
An Adjust Calibration is performed by analyzing a prepared standard of known concentration (calibration
standard). If the concentration displayed on the instrument differs from the calibration standard, the con-
centration displayed on the instrument is adjusted to agree with the calibration standard. The magnitude of
the adjustment is used to calculate an adjustment factor that is applied to all subsequent test results until the
feature is disabled. The same adjustment factor will be applied to all chemical forms selected for that particu-
lar test. If a preprogrammed calibration is adjusted for a particular test, then the range, estimated detection
limit, and precision provided in the test instruction may not apply to the adjusted calibration. After performing
an Adjust Calibration, the acceptability of the adjusted calibration should be determined by testing several
standards of known concentration at various intervals covering the range of the test.
When an Adjust Calibration is performed and entered for a specific test, the Adjust Calibration icon
will
be enabled and displayed in the title bar on all test screens for that test. The AC icon indicates test results are
being calculated using the adjust calibration factor, not the preprogrammed calibration. The Adjust Calibration
option and the AC icon will remain enabled until disabled by the user.
To adjust the calibration of a test, prepare a standard of known concentration (calibration standard) which is
between 70%–80% of the upper test range provided in the test instruction. Using the calibration standard as
the sample, follow the test instruction to obtain a result. If the displayed result does not equal the concentration
of the calibration standard, use the adjust calibration option to adjust the displayed result to agree with the
concentration of the calibration standard.
The following example shows how to use the Adjust Calibration option to adjust the preprogrammed calibra-
tion of the Chlorine F&T DPD/P 4 test. Since the range of this test is 0–4.00 ppm Cl
2
, a calibration standard
is prepared with a concentration of 3.00 ppm Cl
2
(i.e., between 70%–80% of the upper test range). A test is
performed following the Chlorine F&T DPD/P 4 test instruction using the calibration standard as the sample.
The result displayed is 2.90 ppm Cl
2
.