Hach ORBISPHERE 51 Serie Manuel D'utilisation Simplifié page 24

Option
Gas unit type
Gas unit
Liquid
Value
Hold during calibration
Automatic calibration
stop
Interference enabled
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).
7.4.4 Barometric pressure calibration
Note: The barometric pressure sensor has been factory calibrated but should be periodically verified with a
precision certified barometer. This is only necessary if measuring in gas phase with fraction units (%, ppm).
The upper box shows the barometric pressure as measured by the instrument.
Using a precision certified barometer measure barometric pressure in the location where the
measuring instrument is used. Compare the values and if they are the same press Cancel, otherwise
enter the new barometric pressure value in the lower box and press Validation to validate the new
setting.
7.4.5 External pressure calibration (optional sensor)
7.4.5.1 Two point calibration (recommended)
1. Connect a certified absolute pressure gauge to the sample line, and use a certified precision
barometer.
2. The two point calibration starts with barometric pressure for the lower point. Expose the external
pressure sensor to the atmosphere.
3. Enter the barometric pressure read on the barometer in the upper window and validate P1.
4. Expose the external pressure sensor to line pressure, making sure it is exposed to the same
pressure as the certified absolute pressure gauge.
5. Enter the absolute pressure value read on the certified absolute pressure gauge in the lower box,
and validate P2.
Note: Any pressure can be used for P1 and P2, but for an accurate calibration P1 and P2 should be as different
as possible.
24 English
Description
Partial, fraction or dissolved (dissolved is for calibration in a liquid only)
The list of available units depends on unit type selected above.
Select as appropriate.
Enter the gas concentration according to the value in the calibration media.
On by default, this stops any output from the instrument during the calibration
process to avoid sending invalid information to any connected device.
If selected, when the stability criteria is reached, the calibration process stops
automatically.
If selected, this takes into account the influence of interferences during
calibration. By default the same interference as during measurement is selected.