Thermo Scientific INNOVA Series Instruction Manual page 70

Innova Series Operator's Manual
NOTE
If the sample is very high in methane content and also very low in
oxygen content, the unit may not auto-range upscale. If during
sampling the % LEL [%LOW] indication rises rapidly and then
decays, manually switch to the % GAS [%HI] range as described
above to determine the methane content.
Precautions
Be aware that the methane/air mixtures in the range 5% to 15% by volume
are highly explosive. The Innova is Intrinsically Safe, and is not a source of
ignition, but there are many common ignition sources such as static electrical
discharges or sparks from metal tools that can ignite such mixtures. The
relationship between ranges is correct only for methane. Some rough
approximations may be made for gases such as propane and butane, but
values will not be accurate, and should not be used for safety considerations.
WARNING
Initiate Fresh Air Zero adjustment only in a non-hazardous
environment free of combustible or toxic gas content and
consisting of normal oxygen content. To do otherwise could cause a
serious error in the indicated gas level shown on the display, and
result in failure of the Innova LS to properly indicate the degree of
hazard. Also, use care not to initiate Fresh Air Zero immediately
after a range change, as this can cause an error in the "clean air"
baseline.
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