Manual

2-5
Multi-Channel Combustible Monitor Operational Theory 2
Teledyne Analytical Instruments
The response of a catalytic bead detector to a number of gases is
shown in Table 1.
For lighter than air gases, the detectors are generally installed above
the source; for heavier than air gases, detectors are generally installed
below the source.
Table 1
Detector Response to Gases
COMPOUND LEL* RESPONSE FACTOR
Methane 5.0 1.00
Hydrogen 4.0 0.86
Carbon Monoxide 12.5 0.32
Ethane 3.0 1.20
Ethylene 2.7 1.26
Acetylene 2.5 1.39
Propane 2.2 1.42
Propylene 2.0 1.33
Butane 1.9 1.54
Hexane 1.1 1.50
Cyclohexane 1.3 1.44
Heptane 1.05 1.59
Benzene 1.3 1.50
Toluene 1.2 1.48
Ethylene Oxide 3.6 0.76
Methyl Ethyl Ketone 1.8 0.96
Methyl Acrylate 2.8 0.59
* Taken from Fire Hazard Properties of Flammable Liquids, Gases
and Volatile Solids, National Fire Protection Agency.