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A-5
Flue Gas Analysis System Appendix
TELEDYNE BROWN ENGINEERING
Analytical Instruments
Response of Combustible Sensor to Various Gases
Response factors have been determined to relate the sensor output of a
specific compound to the output obtained using methane. A list of some
typical compounds is given in Table 1 along with their LEL (Lower Expo-
sure Limits) values. To determine the output of the sensor for any of the
gases listed, compared to the same concentration of methane, multiply the
reading obtained by the factor listed. For example, if the output is cali-
brated with methane at 2%, the output for ethylene at 2% would be
2.0% X 1.26 = 2.52% methane equivalent.
TABLE 1: Detector Response To Various 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 0.5 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
Pentane 1.5 1.45
Toluene 1.2 1.48
Ethylene oxide 3.6 0.76
Methyl Ethyl 1.8 0.96
Ketone
Methyl Acrylate 2.8 0.59
* Taken from Fire Hazard Properties of Flammable Liquids,
Gases and Volatile Solids, National Fire Protection Agency.
NOTE: For compounds not listed in Table 1, consult the factory.