Specifications

33
2.1.2 Particular Precautions for Combustible Gas Detectors
• The sensors may be desensitized if exposed to certain poisons: silicate vapors at
concentrations > 10 ppm, chlorinated or sulfated products at concentrations > 100 ppm
• A lack of oxygen ( <15% O
2
) or an excess of oxygen ( >23% O
2
) can respectively cause an
under estimation or an over estimation of the actual gas measurement.
• Sensors must be placed upside down during installation.
2.1.3 Response to other explosive gases
The detector should be calibrated with the gas to be measured. If a user wishes to calibrate the
detector with a different gas than the gas it was programmed for at the factory, refer to the table
below, using the recommended gas and the corresponding coefficient.
Table 1: COEFFICIENTS FOR CALIBRATION
Gas
Molecular
Structure
«
LEL LSE Vapor
Density
Coeffici
ent
CH
Coeffici
ent
H
Coefficie
nt
But
Acetone C
3
H
6
O 2.15% 13.0% 2.1 1.65 1.2 0.95
Acetylene C
2
H
2
1.5% 100% 0.9 2.35 1.75 1.35
Ammonia NH
3
15.0% 30.2% 0.6 0.9 0.65 0.5
Butane C
4
H
10
1.5% 8.5% 2 1.75 1.25 1.0
Ethane
C
2
H
6
3.0% 15.5% 1.04 1.5 1.1 0.85
Ethanol C
2
H
6
O 3.3% 19.0% 1.6 1.5 1.1 0.85
Ethylene C
2
H
4
2.7% 34.0% 0.98 1.65 1.2 0.95
Hexane C
6
H
14
1.2% 7.4% 3.0
2.1 1.7 1.2
Hydrogen H
2
4.0% 75.6% 0.069 1.25 1.0 0.8
L.P.G. Prop+But 1.65% ∼9.0% 1.85 1.65 1.2 0.95
Methane CH
4
5.0% 15.0% 0.55 1.0 0.75 0.55
Natural Gas CH
4
5.0% 15.0% 0.55 1.0 0.75 0.55
Octane C
8
H
18
1.0% 6.0% 3.9 2.7 2.0 1.5
Pentane C
5
H
12
1.4% 8.0% 2.5 2.1 1.7 1.2
Propane C
3
H
8
2.0% 9.5 1.6 1.5 1.1 0.85
Toluene C
7
H
8
1.2% 7% 3.14 4.0 2.95 2.3
Unleaded gas 95
«
/ 1.1% ∼6.0% 3 to 4 1.8 1.35 1.05
Recommended gas for calibrating the sensor