Hach ORBISPHERE 3655 Manuel D'utilisation Simplifié page 16

3. Press CAL again within a 3 second period.
4. A measurement will flash on the LCD, showing the gas concentration of the calibration sample.
5. Assuming you know the gas content to be a certain value, you can adjust the displayed value with
the Up/Down Arrow keys.
6. When the reading is adjusted to the known concentration, press CAL again.
7. The instrument displays CAL and returns to the measurement mode.
6.2.3 Calibration in air (oxygen sensors only)
The oxygen sensor can be accurately calibrated in air. To perform this type of calibration, the
instrument must be set for calibration In air.
In order to calibrate the sensor in air, you will need to extract it from its mounting or flow chamber,
and wipe dry the sensor protection grille (if applicable).
Calibration is best achieved using the storage cap that protected the sensor during shipment. Put
several drops of tap water in the cap, shake out the excess, and then attach it to the sensor by
means of its collar. It is best to leave the cap slightly loose, to avoid compressing the air inside. The
cap and sensor should be about the same temperature.
Switch on the instrument, if necessary, and wait a minute or so for the displayed measurement to
settle.
1. Press the CAL button. Remember, this button may have been locked out to prevent an accidental
reset (see Locking out the instrument's CAL button
2. A brief clearing [- - -] message appears.
3. Press CAL again within a 3 second period.
4. The percentage of the measured current to the ideal one is displayed.
5. When the reading is stable, press CAL again.
If the new calibration current is within 25% to 175% of the ideal current, the instrument displays
CAL and returns to the measurement mode. Calibration is now complete, the sensor is
calibrated, and you can proceed with your measurements. If the new calibration current is not
within this range, the instrument displays Err and returns to measurement mode. The system will
not calibrate, and it is likely that a sensor service will be required.
6.3 Calibration range checking
When calibrating the sensor in air or in a span gas, as detailed in
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.
Note: This calibration range checking can be enabled or disabled using the WinLog97 program (see
calibration range checking
measurement situations it may be necessary to disable range checking. This will allow calibration between 0% to
999% of the ideal current. Contact a Hach Lange representative before disabling this range checking feature.
Section 7 Maintenance
7.1 Instrument batteries
The instrument operates on battery power (two standard C-type cells). If battery power should drop,
a LO BAT warning message appears in the instrument LCD's top-left corner.
To install the batteries, unscrew the battery cap (on the right side of the instrument) with a coin or flat
screwdriver, place the cells lengthwise into the battery compartment (positive end first), and then
replace the cap. Refer to the diagram on the back of the instrument.
Rechargeable nickel-cadmium batteries may be used - expect about 40 hours of autonomy. Alkaline
batteries provide the longest continuous use though mercury-free batteries are available that present
less of a disposal problem.
16 English
on page 14). It is recommended to leave this checking feature enabled. In special
on page 14 for details).
Sensor calibration on page 15, the
Sensor