TX9165 User Manual
TX9165-UM-EN-07 25
Discrimination
Catalytic combustion sensors can detect a wide range of flammable gases but they
cannot discriminate between individual gases. They will respond to most, or all,
of the flammable components present in the atmosphere without distinguishing
between them.
Infrared sensors are highly specific to the defined gas type and may NOT respond
to other similar gases.
Contamination
The response of catalytic combustion gas sensors can be affected by air borne
contaminants which will reduce the sensitivity. Substances such as silicones, tetraethyl
lead, sulphur compounds and phosphate esters can cause permanent degradation
(poisoning). Hydrocarbons may also cause temporary inhibition.
Interference
If the atmosphere to be monitored contains a gas that dilutes or displaces the
air, this may reduce the response of catalytic sensors. Similarly, steam laden
atmospheres and condensation can reduce the stability.
High Concentrations of Flammable Gas
Exposure of low concentration catalytic combustion sensors to concentrations of
flammable gas greater than the LEL can affect the sensitivity and zero stability of
catalytic elements and the calibration should be checked after such an exposure.
Toxicity
Be aware that most flammable gases and vapours are also toxic at low
concentrations of LEL.
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