99
Combustible Gases
Tables A.2 and A.3 provide the LEL for select combustible gases as they apply to specific sensors. These
tables also provide correlation factors that can help determine the percentage LEL when the actual gas
differs from the gas that was used to calibrate the instrument.
For example, if the instrument reads 10% LEL in a pentane atmosphere, and was calibrated to methane,
the actual percentage LEL is determined as follows:
1. Locate the table cell where the sample gas (pentane) intersects with the calibration gas (methane).
2. Multiply the cell's value (2.02) by the unit's LEL reading (10%) to calculate the actual concentration of
20.2% LEL.
Table A.2 LEL correlation factors for the sensors 17155304-K, -L, and -M
Sample gas
LEL
(% vol)
Calibration gas
Butane
Hexane
Hy-
drogen
Methane
Pentane
Propane
Acetone
2.5%
1.00
0.70
1.70
1.70
0.90
1.10
Acetylene
2.5%
0.70
0.60
1.30
1.30
0.70
0.80
Benzene
1.2%
1.10
0.80
1.90
1.90
1.00
1.20
Butane
1.9%
1.00
0.58
1.78
1.67
0.83
1.03
Ethane
3.0%
0.80
0.60
1.30
1.30
0.70
0.80
Ethanol
3.3%
0.89
0.52
1.59
1.49
0.74
0.92
Ethylene
2.7%
0.80
0.60
1.40
1.30
0.70
0.90
Hexane
1.1%
1.71
1.00
3.04
2.86
1.42
1.77
Hydrogen
4.0%
0.56
0.33
1.00
0.94
0.47
0.58
Isopropanol
2.0%
1.10
0.90
2.00
1.90
1.00
1.20
Methane
5.0%
0.60
0.35
1.06
1.00
0.50
0.62
Methanol
6.0%
0.60
0.50
1.10
1.10
0.60
0.70
Nonane
0.8%
2.22
1.30
3.95
3.71
1.84
2.29
Pentane
1.4%
1.21
0.71
2.15
2.02
1.00
1.25
Propane
2.1%
0.97
0.57
1.72
1.62
0.80
1.00
Styrene
0.9%
1.30
1.00
2.20
2.20
1.10
1.40
Toluene
1.1%
1.53
0.89
2.71
2.55
1.26
1.57
Xylene
1.1%
1.50
1.10
2.60
2.50
1.30
1.60
JP-4
—
—
—
—
—
1.20
—
JP-5
—
—
—
—
—
0.90
—
JP-8
—
—
—
—
—
1.50
—