Technical data
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Function Restrictions depending on Oxygen Concentration
Take note, that the measurement of gas and/or vapour concentrations in the range up to 100 % LEL
cannot be done accurately, if simultaneously the oxygen concentration is less than 10 Vol. %. In this
case the pellistor suffers from a lack of oxygen necessary for the „catalytic combustion“.
The Ex approval is not valid for using the transmitter in oxygen enriched atmospheres with
concentrations of more than 25 Vol.% oxygen.
Display Irritation due to Sensor Poisons
Certain parameters, known as "sensor or catalyst poisons", may affect the signal behaviour of the
sensor. The "sensitivity", i.e. the capability to emit signals, is being reduced. Sensor poisons are e.g.
sulphur, lead and silicon vapours. Usually these components are found very rarely or in very low
concentrations only.
Please draw your special attention to any interfering gases, which might be present at your detection
place and which might affect the proper functioning of your gas monitoring system. Depending on
the type of gas and its concentration, this affect may result in failures like a more or less steady, long-
term loss of sensitivity or even to a sudden and considerable drop of sensitivity (see also
DIN EN 50073).
Trouble Shooting
Failure Cause Solution
Zeropoint cannot be adjusted Sensor is faulty Replace sensor
Sensitivity cannot be adjusted Sensor is faulty Replace sensor
Output current is fallen to 0 mA Fuse is blown
Line is interrupted
Replace fuse
Re-connect
Lower Explosion Limits (LEL) of Gases subject to Function Test
Gas Formula LEL as per EN 61779
Function test
LEL as per data base
Chemsafe
Methane CH
4
4.4 Vol% 4.4 Vol%
Propane C
3
H
8
1.7 Vol% 1.7 Vol%
Hexane C
6
H
14
1.0 Vol% 1.0 Vol%
Nonane C
9
H
20
0.7 Vol% 0.7 Vol%
Toluene C
6
H
5
-CH
3
1.1 Vol% 1.2 Vol%
Aceton CH
3
-CO-CH
3
2.5 Vol% 2.5 Vol%
Hydrogen H
2
4.0 Vol% 4.0 Vol%
Ethylene CH
2
=CH
2
2.3 Vol% 2.4 Vol%
Diethyl ether C
2
H
5
-O-C
2
H
5
1.7 Vol% 1.7 Vol%
Ethyl acetate CH
3
-COO-C
2
H
5
2.2 Vol% 2.0 Vol%
Isopropanol CH
3
-CHOH-CH
3
2.0 Vol% 2.0 Vol%
Ammonia NH
3
15.0 Vol% 15.4 Vol%