Calibration Parameters - Offset And Slope; Calibration Options; Scheduled Calibration; Monitoring Calibration Progress - ABB Navigator 500 Series Operating Instructions Manual

Navigator 500
Sodium analyzer
5.4 Calibration parameters – offset and slope
A mV offset is calculated after a single-point or a two-point
calibration. This value represents the difference in millivolt output
of the electrode pair compared to the ideal output. The slope is
calculated when a two-point calibration is performed and is an
indication of the quality of the electrode pair. A two-point
calibration can fail if the slope value is outside the pass criteria
set in the software – refer to Table A.2, page 75, for a
description of the calibration pass limits.

5.5 Calibration options

Single-point or two-point calibrations can be performed
depending on the operating conditions. A single-point
calibration (low and high) adjusts the mV offset only, a two-point
calibration adjusts the mV offset and the slope (sensitivity) of the
electrode.
Note. Perform a low-point calibration weekly and a
two-point calibration monthly. However, a suitable schedule
must be set to suit the operating conditions and
applications.

5.5.1 Scheduled calibration

Automatic calibrations can be performed with a frequency of 1
day to 8 weeks. Perform calibrations frequently to ensure
accurate readings and verify the performance of the
wet-section.
To set up a scheduled calibration:
1. Access the configuration level Calibrate menu –
see Section 5.1, page 21.
2. Configure the schedule at the Sensor 1 (4) (single-stream)
or Sensor Three Stream / Scheduled Calibration / Type,
Frequency, Interval and Time of Next Cal. menu options.
24

5.5.2 Monitoring calibration progress

If the Calibration page is exited by press the
OK prompt) before the calibration has completed, progress can
be monitored from the View mode – see Fig. 5.1.
Navigator
PV 2.93
SS1 100
Low Calibration
Calibrating
Fig. 5.1 Calibration view
At the end of the calibration, and if the calibration is successful,
the Active Slope, Active Offset, Last Slope and Last Offset
values in the Signals View are updated – see Section 6.6,
page 33 for details of View modes.
Note. The Active Slope and Active Offset values are not
updated if the calibration fails. The Calibration Log is
updated with the Active Slope and Active Offset values.

5.5.3 Abort calibration

Calibrations can be stopped manually by pressing the
(below the Abort prompt) while the Calibration page is displayed
(see page 22).
The calibration valve closes enabling the sample to flow past the
sensor again. A calibration recovery period commences and the
Calibration Log displays Cal Aborted – see Section 6.7.1, page
35.
If the pressure switch on the constant-head unit detects there is
no solution present during the calibration, the calibration is
stopped automatically. The Diagnostic Log (see Section 6.7,
page 34) displays a Cal Failed diagnostic and No Low Cal or No
High Cal depending on the valve that was energized. The
Calibration Log displays a Cal Aborted entry – see Section
6.7.1, page 35.
5 Calibration
key (below the
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OI/ASO550–EN Rev. G