Dräger Polytron 3000, Instructions Manual

Page: 14 / 68

Maintenance
14
Unit calibration
— Ensure that the sensor is warmed up before it is calibrated. See the sensor data
sheet for the warming-up time.
— Only the zero point is checked if an oxygen sensor has been fitted. The zero
point of an oxygen sensor does not require calibration.
— The transmitter can be calibrated by the operator on site.
— For critical applications , the calibration intervals should be defined in accor-
dance with the recommendations in EN 50073
1)
, EN45544-4
2)
and national re-
gulations.
Note the calibration sequence!

First check the zero point and correct it necessary, Immediately after this, check
the sensitivity and adjust it as necessary.
— Never calibrate the sensitivity before calibrating the zero point.
— Zero gas and test gas: see the information in the sensor data sheet.

Open the front cover of the service port with an Allen key by turning anticlockwise
(approx. 60
o
). The maintenance switch and potentiometers for calibration are
now revealed.
Measuring / maintenance mode
1 Maintenance switch with two positions.
2 Measuring mode position (left-hand position) – measured values are relayed to
the analogue output.
3 Maintenance mode position (right-hand position) – a maintenance signal (3.4
mA ±0.2 mA constant) is relayed to the analogue output and prevents alarms
being triggered.
CAUTION
When the transmitter is installed in Ex areas Class II, Div. 1 & 2, Group E, F, G,
the opening of the housing (required for calibration) must not be done when con-
nected to power (power must be turned off or the area has to be temporarily
declassified). Explosion hazard!
1)
EN 50073 – Guidelines for selection, installation, use and maintenance of devices for
the detection and measurement of flammable gases and oxygen.
2)
EN 45544-4 – Electrical devices for the direct detection and direct concentration
measurement of toxic gases and vapours – Part 4: Guidelines for selection, installa-
tion, use and maintenance.
CAUTION
Test gas must not be inhaled. Risk to health! Care must be taken about the
risks which can arise when using test gas; hazard instructions and safety advice
must be observed.
For details, see appropriate DIN Safety Data Sheets.
CAUTION
Use only a 5 mm Allen key without a ball head.
NOTE
The Dräger Polytron 3000 does not support the storage of calibration data in the
sensor data base.
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