Atest Gaz Sigma SmArt, User Manual

Page: 46 / 84

www.atestgaz.pl
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
When gas concentrations in the atmosphere differ significantly from those indicated in the table 1, it is
necessary to conduct the analysis of the impact of such a situation on the detector operation.
Catalytic sensor working properly at an oxygen concentration of about 21%.
3.1.1 Impact of the presence of a working gas or other reaction gas
Catalytic sensor isn't selective – it reacts (with different sensitivity) to most flammable substances appearing
in its surroundings. Because of that it is necessary to consider their presence when the sensor is operating.
When using detectors with catalytic sensors, it is necessary to be aware that:
long-term presence of significant concentrations results in faster sensor wear. Basically, catalytic
sensors are used to detect the incident presence of combustible gases. They should not work in
atmospheres in which flammable gases at concentrations greater than about 20% LEL occur in a
continuous or prolonged manner, as it may lead to a rapid reduction of their sensitivity and the
appearance of a zero drift,
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. 3/5 Appendix: PU-Z-054-ENG R02
•