9.3
Zero calibration
Ambient air can be used to zero the sensor instead of
Nitrogen or Synthetic Air only if the area is known to be free of
the target gas or any gas to which the sensor may be cross-
sensitive (as listed on the sensor data sheet). In this case, no
cylinder or calibration adapter is needed for the zero
calibration.
WARNING
Calibration fault at zero calibration
Insufficient ambient air flow may cause calibration errors.
► Make sure that the ambient air flow to the sensor is
sufficient.
®
Polytron
5100 EC-specific:
It is not possible to zero calibrate Oxygen (O
therefore this function is not displayed in the transmitter
menu.
®
Polytron
5200 CAT-specific:
Sensors must not be calibrated with pure nitrogen. Catalytic
sensors need oxygen to work properly.
®
Polytron
5720 IR-specific:
®
For Polytron
5720 IR (with PIR 7200 to detect carbon
dioxide), only Nitrogen or Synthetic Air without any CO
content may be used for a zero calibration.
9.3.1 Performing zero calibration
Prerequisites:
– Sensor has finished the warm-up phase
– Calibration is prepared.
All instruments except Polytron 57x0 (IR)
Perform zero calibration:
1. Select -0- Adj and confirm with [OK]
The Maintenance signal is transmitted by the analog
interface, no alarm or fault relays are switched.
The display will show the current value blinking (e.g.
2).
2. Apply synthetic air or nitrogen, if ambient air cannot be
used.
a. Set gas flow corresponding to the sensor used (see
"Gas flow for calibrations", page 16)
After the test gas has been applied to the sensor for 3
minutes and the displayed value is stable perform
calibration.
3. Use [UP] / [DOWN] to adjust the value to 0.
4. Acknowledge with [OK]; the instrument will return to the
main menu.
The zero point is calibrated.
5. Turn off gas flow and remove the calibration adapter from
the sensor or disconnect tubing.
Dräger Polytron
) sensors,
2
2
®
5000 Series
Polytron 57x0 (IR)-specific
Perform zero calibration:
1. Select -0- Adj and confirm with [OK]
The Maintenance signal is transmitted by the analog
interface, no alarm or fault relays are switched.
The display will show 'walking dashes' and then toggle
between 'CAL' and the current value (e.g. '0.1').
2. Apply synthetic air or nitrogen, if ambient air cannot be
used.
a. Set gas flow corresponding to the sensor used (see
"Gas flow for calibrations", page 16)
After the test gas has been applied to the sensor for 3
minutes and the displayed value is stable perform
calibration.
3. Tap [OK].
If the calibration was successful, the display will toggle
between 'CAL' and 'OK'. Otherwise it will toggle
between 'CAL' and 'FAIL'.
– If [OK] is not acknowledged within approximately 5
minutes, the instrument will time out and the display
will toggle between 'CAL' and 'FAIL'.
– If [UP] is tapped the calibration will be aborted. The
instrument will return to the main menu.
4. Acknowledge with [OK]; the instrument will return to the
main menu.
5. To go back to measuring mode, select [UP].
6. Turn off gas flow and remove the calibration adapter from
the sensor or disconnect tubing.
9.4
Span calibration
®
Polytron
5200 CAT / 5310 IR / 5700 IR - specific:
The span calibration has to be performed within 24 h after the
last valid zero calibration.
®
Polytron
5310 IR-specific:
Due to the design of the DSIR gas sensor, the output signal of
the gas sensor is limited to 45 % . . . 55 % of the instrument-
internal supply voltage. If the gas concentrations increase
further after the maximum sensor output signal has been
reached, this does not lead to an increase of the values
displayed on the instrument response transmitted to the
central device. In case of substances with particularly low
calibration factors and/or manual configuration of a high span
calibration factor at the sensor, this may already happen at
concentrations below 100 %LEL. For substitute gas
calibrations, correct triggering of the alarm should therefore
be checked with a test gas concentration corresponding to the
alarm threshold. If necessary, the measuring range which can
be represented can be increased as required by a reduction
of the sensor output signal (see DSIR Instructions for Use,
part number 9023981) and subsequent calibration at the
instrument.
9.4.1 Performing span calibration
Prerequisites:
– Zero-point is calibrated.
– Calibration is prepared.
Calibration
en