Hach Orbisphere 510 Manuel D'utilisation De Base page 21

7.4.2 EC gas sensor calibration
7.4.2.1 Calibration of the measured gas
1. 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.
Option
Calibration mode
Medium
Concentration unit type Partial, fraction or dissolved (dissolved is for calibration in a liquid only)
Concentration unit
Liquid
Value
Hold during calibration
2. Press OK to start calibration
• 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. 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).
7.4.2.2 O sensor calibration
2
The O sensor needs to be calibrated after each sensor service. Wait at least 30 minutes after
2
mounting a new membrane before re-calibrating. The sensor is in contact with either:
• Air at atmospheric pressure (In Air)
• O at known concentration (Direct value). The gas can be dissolved or not.
2
In air calibration
This calibration procedure places the O
reference against which to calibrate.
Dry the sensor thoroughly, before placing the sensor storage cap under tap water. Shake off any
excess water, but leave a few drops inside the cap. Verify that the screw-on protection cap is in place
on the sensor head. If you use a Dacron mesh inside the protection cap, make sure it is dry before
Description
2 types available, depending on the gas being measured:
• Direct value: Any gas
• In Air (default): For O
2
Select liquid or gas (direct calibration only)
The list of available units depends on unit type selected above.
Select as appropriate, available when liquid has been selected in medium
(above).
Enter the gas concentration according to the value in the calibration media, when
direct value is used.
On by default, this stops any output from the instrument during the calibration
process to avoid sending invalid information to any connected device.
sensor in water-saturated air, to provide a known oxygen
2
or O
3
English 21