Calibration; Calibration Diagnostics; Calibration Diagnostic Reset - Honeywell DirectLine DL421 User Manual

Calibration

4.1 Calibration Diagnostics

Introduction
The manual and automatic standardization and slope adjustments change the zero
offset and the percent theoretical slope calibration diagnostics used by this system.
These values are viewed as read-only information. It is good practice to observe
these values after calibration. Monitoring the values over time will help you predict
when the electrode will need to be replaced.
Zero Offset pH Value
When Online pH value is displayed, PRESS
current Zero Offset value in fixed hundredths decimal position.
Zero Offset is non-volatile and is initialized to 0.00 pH at unit reset.
It has a range of –2.00 pH to +2.00 pH and it is updated after each calibration.
Percent Theoretical Slope Value
When Online pH value is displayed, PRESS
current Percent Theoretical Slope value in fixed tenths decimal position.
Percent Theoretical Slope is non-volatile and is initialized to 100.0 % at unit reset.
It has a range of 80.0 % to 105.0 % and it is updated after each calibration.
60 Second Timeout
If no key is pressed for 60 seconds, the display will abort the entry mode and default
to Online Display.

4.2 Calibration Diagnostic Reset

Introduction
When a new electrode is installed, the indicated pH will use the zero offset and
percent theoretical slope values from the previous calibration. Depending on the
condition of the replaced electrode, the difference between the known and indicated
pH of the new electrode may vary as much as several pH units. A calibration on the
new electrode will correct this difference.
ATTENTION:
If Auto Buffer Recognition (ABR) calibration is used when the new electrode is calibrated for the first time,
the ABR calibration may select a buffer value from the selected standard buffer group table (Table 4-1)
that is directly above or below the actual buffer value.
To avoid this discrepancy, follow one of the two procedures listed below:
1. Select the correct buffer value by following Step 2B of Table 4-3.
2. Perform a calibration diagnostic reset as described below prior to performing an ABR calibration on
the new electrode.
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4. Calibration
DirectLine® DL421 Sensor Module User Manual
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