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Appendix
B
I
NTERFERENCE
F
ACTORS
The following factors interfere with the accurate gas measurement capability
of the Innova:
• Filament poisoning
• Rich mixtures
• Oxygen-deficient mixtures
• Oxygen-enriched mixtures
• Interfering gases
• Response to various combustible gases
Filament Poisoning
Silicone vapors and chlorine and fluorine compounds, such as chlorinated
hydrocarbons, can damage the HC sensor and interfere with accurate LEL
readings.
Such compounds, even in small proportions, should be avoided. Verification
checks on known gas samples are necessary, if the possibility of exposure to
these compounds exists.
High Concentration of Combustible Gas
With rich mixtures of combustible gases, the instrument displays the
following indications (refer to Table B-1)
Table B-1
Indications with High Combustible Gas
Concentrations
Cause
Indication
Mixtures up to 100% LEL
Reading displayed.
Mixtures between LEL and
Upper Explosive Limit (UEL)
100% displayed.
Mixtures above the UEL
The reading increases to 100% LEL, then
comes back down. Very rich mixtures read
close to zero.
