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Innova Series Operator’s Manual
Oxygen-Deficient Mixtures
Samples containing less than 10% oxygen may give low LEL readings by
starving the combustible gas reaction in the sensor. Such mixtures will also
cause a low oxygen alarm. As a rule, 10% oxygen or more gives a full reading
on any combustible gas up to the LEL.
Oxygen-Rich Mixtures
Samples containing combustible gases that have more than normal proportion
of oxygen will give a normal reading. However, they should be avoided
because the flame arrestor used is not dense enough to arrest flames from
combustible gas in oxygen. Such mixtures will also cause a high oxygen
alarm.
WARNING
Do not attempt to use the Innova on samples of combustible gas in
oxygen; for example, oxy-acetylene mixtures. Instead, use sample
mixture in air.
Interfering Gases
The CO sensor responds to some other gases besides CO. The CO sensor has
a charcoal filter that prevents interference from H
2
S and some of these other
gases. However, continuous exposure may saturate the filter and break
through as CO indication. Hydrogen, ethylene, and acetylene will pass
quickly through the filter, and thus are strong interferences, while heavier
olefins and aromatic hydrocarbons will break through in time, making sensor
replacement necessary.
