Detcon FP-624D - Manual (Page 26)

Model FP-624D
FP-624D Instruction Manual Rev. 1.2 Page 22 of 42
NOTE: The default value for gas factor is 1.0. This would be used when methane is the target
gas. Values other than 1.0 would be used when the target gas is not methane.
Set Gas Factor is used to make the appropriate signal sensitivity adjustment when the target gas is a gas other
than methane. This is necessary because the catalytic bead sensor has different signal strengths for each
combustible gas and all reading calculations are made based on a reference to methane. The gas factor value is
adjustable from 0.2 to 5.0.
It represents the translation between the target gas and methane gas, where
methane has a normalized gas factor = 1.0. For example, the gas factor for butane is 1.71, because the signal
strength of butane is 1.71 times lower than methane. The current setting can be viewed in View Program
Status – Gas Factor.
The following table shows the gas factors of most combustible gases that can be measured. Find the target gas
and enter the corresponding value as the gas factor. For example, if butane were the target gas, the correct gas
factor would be 1.71. If there is a mixture of target gases, use a weighted approach to determine the correct
gas factor. For example, if the target gas was 50% butane and 50% methane, the correct gas factor would be
calculated and entered as 0.5(1.71) + 0.5 (1.0) = 1.35.
Table 2 Gas/Cal Factors
Gas Factor Gas Factor Gas Factor
Acetaldehyde 1.66 Decane 3.05 Dimethyl Ether 1.60
Acetic Acid 1.84 Diethylamine 2.05 Methylethyl Ether 2.27
Acetic Anhydride 2.17 Dimethylamine 1.73 Methylethyl Ketone 2.42
Acetone 1.93 2,3-Dimethylpentane 2.51 Methyl Formate 1.49
Acetylene 1.76 2,2-Dimethylpropane 2.52 Methyl Mercaptan 1.64
Alkyl Alcohol 1.96 Dimethyl sulfide 2.30 Methyl propionate 1.95
Ammonia 0.79 1,4-Dioxane 2.24 Methyl n-propyl Ketone 2.46
n-Amyl Alcohol 3.06 Ethane 1.47 Naphtha 3.03
Aniline 2.54 Ethyl Acetate 1.95 Naphthalene 2.94
Benzene 2.45 Ethyl Alcohol 1.37 Nitromethane 1.72
Biphenyl 4.00 Ethylamine 1.90 n-Nonane 3.18
1,3-Butadiene 1.79 Ethyl Benzene 2.80 n-Octane 2.67
Butane 1.71 Ethylcyclopentane 2.52 n-Pentane 2.18
iso-Butane 1.93 Ethylene 1.41 iso-Pentane 2.15
Butene-1 2.20 Ethylene Oxide 1.93 Propane 1.81
cis-Butene-2 2.06 Diethyl Ether 2.16 n-Propyl Alcohol 2.12
trans-Butene-2 1.97 Ethyl Formate 2.26 n-Propylamine 2.07
n-Butyl Alcohol 2.91 Ethyl Mercaptan 1.78 Propylene 1.95
iso-Butyl Alcohol 1.89 n-Heptane 2.59 Propylene Oxide 2.18
tert-Butyl-Alcohol 1.34 n-Hexane 2.71 iso-Propyl Ether 2.29
n-Butyl Benzene 3.18 Hydrazine 2.22 Propyne 2.40
iso-Butyl Benzene 3.12 Hydrogen Cyanide 2.09 Toluene 2.47
n-Butyric Acid 2.63 Hydrogen 1.30 Triethylamine 2.51
Carbon Disulphide 5.65 Hydrogen Sulphide 2.54 Trimethylamine 2.06
Carbon Monoxide 1.32 Methane 1.00 Vinyl Chloride 2.32
Carbon Oxysulphide 1.07 Methyl Acetate 2.01 Vinyl Ethyl Ether 2.38
Cyanogen 1.12 Methyl Alcohol 1.16 o-Xylene 2.79
Cyclohexane 2.43 Methylamine 1.29 m-Xylene 2.55
Cyclopropane 1.60 Methylcyclohexane 2.26 p-Xylene 2.55