Hach-Lange ORBISPHERE 410 User Manual - Manual (Page 55)

53
Calibration Menu
7.3 TC gas sensor calibration
Calibration of the measured gas
Start Before initiating a calibration process, the calibration parameters must be
set by pressing on the Modify button. The last calibration parameters are
memorized, so this step can be ignored if the correct parameters are
already set.
Similarly, if only the calibration value has changed, then this can be updated
directly instead of pressing the Modify button.
Note:
When calibration is started, a calibration event is set, and the analog
output and relay are put on hold (if selected below) to avoid unwanted alarms
or potential process problems. This resumes when calibration is finished.
Modify calibration
parameters • Gas Phase : Select liquid or gas (direct calibration only)
• Gas unit type : Partial, fraction or dissolved (dissolved is for
calibration in a liquid only)
• Gas unit : The list of available units depends on unit type selected
above.
• Liquid : Select as appropriate.
• Enter the gas concentration according to the value in the calibration
media.
• Hold during calibration : On by default, this stops any output from the
instrument during the calibration process to avoid sending invalid
information to any connected device.
• Automatic calibration stop : If selected, when the stability criteria is
reached, the calibration process stops automatically.
• Interferences enabled : Option not available.
Press OK to start calibration
Calibration results A calibration screen will be displayed showing current measurement data
which is continually refreshed.
The value “% ideal current” is a percentage of the current against the ideal
current for the membrane type selected. If this percentage is not within the
accepted range, an error message is displayed and the calibration process
fails (see
Calibration errors (EC and TC sensors) on page 54 ). A warning
message can be displayed when this value is close to the boundaries, but
when calibration can be accepted.
The message is first displayed in the result box. The dialog box with the
error message or the warning is displayed when the finish button is pressed.
The value “% last calibration” shows the ratio between the current
measurement and the previous sensor calibration.
The value “% variation” indicates the variation during the last 3
measurements, which is the stability of the measurements. A variation as
low as possible is needed for a precise calibration.
The display shows the actual calibration parameters, and the actual
readings (temperature, barometer, current).
Note:
In case of calibration failure, consider replacing the membrane. See
the sensor maintenance manual for details.
Verification Similar to the calibration procedure, but for verification of the actual
calibration values. The result of the measurements made during the
verification is not stored and the actual calibration data is not modified.