Dansensor A/S COPYRIGHT © PBI-200114-D 04/2013
ISM-3 EN User Manual 19
6. Calibration
Besides atmospheric air, you can calibrate with up to 4 calibration gases. If an offset adjustment has
been made after the last calibration, a calibration of ISM-3 must always be started from the beginning
again, meaning that calibration with 20.946% O
2
must be carried out initially. If an off set adjustment has
been made and calibration is attempted with another gas than 20.946 % O
2
the error message ER.8 will
appear (cannot calibrate after the offset adjustment).
When calibrating with 20.946 % O
2
the result is compared with the latest 20.946 % O
2
calibration. All
other calibrations are adjusted using the difference between the new and the preceding 20.946 % O
2
calibration. If an offset adjustment has been carried out, it is reset. After the calibration with 20.946 % O
2
,
calibration must be performed with the selected calibration gases. See below.
Besides the calibration with 20.946% O
2
it is recommended to calibrate ISM-3 with minimum 2 gases in
the range in which you will measure later on. The calibration gas values should lie above and below the
range in which you will measure later on.
Note: ISM-3 must warm up for at least 1 hour before making the calibration.
Calibration
The following procedure must be used in order to calibrate ISM-3:
1. Before the calibration is started, it must be assured that the measurement can be started via the
button and that the measurement cannot be started/ stopped via an external measurement control
signal during the calibration. You can choose manual start/stop measurement alone, by setting the
first digit in the
PA parameter in the set-up menu to "0 - - - -". Make a note of the setting before
making the change.
2. If ISM-3 is not equipped with an internal pump: Connect the calibration gas to gas in and adjust the
input pressure in order to produce a flow of 125±5ml/min.
If ISM-3 is equipped with an internal pump: Establish a gas overflow of approx. 0.5 l/min and let ISM-
3 suck the calibration gas from here.
3. Start the measurement with .
4. Let ISM-3 measure on the gas for at least 4 minutes. When calibrating with gases of less than 1000
ppm it is recommended to measure for about 10 minutes. Then check that the output of O
2
in the
display is stable for about 1 minute before carrying out the calibration.
When the output is stable check that the output O
2
value corresponds to or is very close to the
analysis value of the calibration gas. If this is not the case, check for leaks in the measurement gas
hose and for a sufficient gas supply pressure.
5. Go to the calibration menu
- Press and hold the buttons and about 3 seconds until display shows
set.
- Press twice and the calibration menu
CAL. is shown.
6. Press and the value for the first calibration gas
CAL1 will appear. The calibration gas number 1 is
reserved for calibration with 20.946 % O
2
(atmospheric air) and cannot be changed. In case of
calibration with 20.946 % O
2
choose this field. If the calibration gas is different from 20.946% O
2
,
press button until an empty field appears (a field for the readout of 0 ppm) or a field with an old
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