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3 Impact of environmental conditions
Never exceed the rated operating parameters of the detector. These parameters can be
found in the detector calibration certificate.
The detector must be used in accordance with the provisions in the User's Manual.
3.1 Composition of the controlled atmosphere
It is assumed that the standard composition of the atmosphere is a mixture of gases with the proportions
indicated in table 1.
Ingredient C [% vol] C [ppm]
Nitrogen 78.084 780 840
Oxygen 20.946 209 460
Argon 0.934 9 340
Carbon dioxide 0.0360 360
Neon 0.00181 18.18
Helium 0.00052 5.24
Methane 0.00017 1.70
Krypton 0.00011 1.14
Hydrogen 0.00005 0.50
Xenon 0.000008 0.087
Table 1: Typical composition of atmospheric air
3.1.1 Impact of the presence of a substance in a controlled atmosphere
The semiconductor sensors are non selective (cross sensitivity).
Presence of corrosive gases (e. g. NH
3
, H
2
S, SO
2
) causes a decrease in the sensor's sensitivity.
Reactive gases (e. g. SO
2
, NO
x
) can overstate or lower received signals.
Prolonged high working gas concentrations have an influence on the sensor characteristics,
regardless of whether the sensor is energized or not. In extreme cases it is possible to irreversibly
damage the sensor.
The prolonged presence of low working gas concentrations causes a slow saturation of the sensor.
3.1.2 Effect of oxygen concentration value
The concentration of oxygen affects the operation of the sensor. The semiconductor sensor should operate
in an atmosphere of standard oxygen concentration. The minimum permissible oxygen concentration at
which a semiconductor sensor can operate is 18%.
Atest-Gaz A. M. Pachole sp. j.
ul. Spokojna 3, 44-109 Gliwice, Poland
VAT No.: PL 9691433231
tel.: +48 32 238 87 94
fax: +48 32 234 92 71
e-mail: contact@atestgaz.pl
p. 3/4 Appendix: PU-Z-030-ENG R02
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