Hach ORBISPHERE 3650 ATEX Manuel D'utilisation De Base page 19

When set to Enabled, at calibration the measurement current should be between 25% and 175% of
the ideal current; if the value is outside of these limits, the calibration fails and Err is displayed on the
instrument LCD. Choose OK when the desired mode is selected.
Note: It is recommended to leave range checking enabled. In special measurement situations it may be necessary
to disable range checking. However, contact a Hach Lange representative for further details before disabling this
feature.
7.4.6 Entering a span gas value
When calibrating the sensor in a span gas, use the Configuration, Span Gas menu to enter the
concentration of the gas to be measured in the span gas. Enter the percentage of measurement gas
in the span gas (e.g. 10.00%), then choose OK.
7.4.7 Dual use (model 3650/113 only)
7.4.7.1 Change from the PC
Use the Configuration, Dual Use menu to change the measurement phase (either dissolved or
gaseous) for the model 3650/113 dual-use analyzer. Choose ppm (dissolved) to set the instrument
for dissolved measurement in liquids, or % (gaseous) to set the instrument to gas phase
measurement.
7.4.7.2 Change from the instrument
1. Switch the instrument power OFF
2. Switch the instrument on by holding down the Down Arrow button and then pressing the
POWER button while still pressing the Down Arrow button
3. The instrument will first display USE followed by either dIS for dissolved phase measurement in
liquids or gAS for gaseous phase measurement
4. Use the Up/Down Arrow buttons to change the mode to your choice
5. Press the STO button to set the selected mode. The instrument displays Sto for a few seconds,
then returns to measurement mode
Section 8 Calibration
8.1 Pressure calibration
Since the instrument is sealed against moisture, you must open the barometric pressure sensor relief
valve switch on top of the instrument to permit the instrument to achieve atmospheric pressure
equilibrium, and take an accurate barometric pressure reading. This must be done with every
calibration. To open the relief valve, depress and hold down for five seconds, then release.
If you have access to an accurate barometer, you may wish to calibrate the instrument's internal
barometric pressure sensor. This is done using the PC WinLog97 program. Choose
Troubleshooting, Pressure Calibration and an informational message will appear to warn you that
the instrument's current pressure calibration will be lost.
Choose OK to continue. The calibration procedure then displays a Pressure Calibration dialog box.
The Measured Pressure value shows the current instrument pressure reading.
Enter the current atmospheric pressure, in mbars, in the Calibration Pressure entry box. Choose
Calibrate to direct the instrument to read and display the Measured Pressure using this calibration
value. Choose Quit when you are satisfied with the pressure calibration to return to normal
operation.
8.2 Calibration range checking
When calibrating the sensor in air or in a span gas, as detailed in
the new calibration current should be between 25% to 175% of the ideal current (which is stored in
the instrument's non-volatile memory for each membrane). If not, the instrument displays Err on its
LCD and the system will not calibrate. When the system will not calibrate, it is likely that a sensor
service will be required.
Sensor calibration on page 20,
English 19