Table – INFICON Composer Gas Concentration Controller User Manual
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Composer Operating Manual
to a range of about 1.1 to 1.7 for almost every known gas. Consequently,
guesses that are wrong don’t make a lot of practical difference if they are
reasonable guesses. It is also possible to make intelligent guesses about
unknown gasses using the value of the Specific Heat Ratio for a similar gas.
Interestingly, it is almost always more accurate to overestimate the Specific
Heat Ratio than to underestimate by the same amount; see
and
. Consider also that in production the accuracy is not as important as
the reproducibility. As long as the Specific Heat Ratio is not changed the
Instrument System will reproduce the results day after day.
Table 3-1 Common Molecular Weights and Specific Heat Ratios
Gas Name
Molecular
Weight
Specific
Heat
Ratio
Gas Name
Molecular
Weight
Specific
Heat
Ratio
Ammonia
(NH
3
)
17.030
1.316
R134a
102.000
1.120
Argon
39.948
1.667
SiBr
4
347.702
1.094
AsH
3
77.950
1.269
SiCl
4
169.900
1.101
B
2
H
6
27.670
1.165
SiF
6
142.080
1.127
CBr
4
331.627
1.100
SiFH
3
50.1
1.213
CO
2
44.010
1.288
SiHCl
3
135.450
1.123
Cp
2
Mg
154.49
1.2
TEAM - DMZn
196.65
1.10
Cupra-select 370.830
1.052
TDEAT
336.10
1.2
DETe
185.72
1.100
TDMAT
224.0
1.2
Deuterium
4.032
1.398
TEGa
156.910
1.103
DMHy
60.10
1.16
TEOS
Si-(C
2
H
5
O)
4
208.26
1.2
DMZn
95.450
1.120
TMAl
72.090
1.230
Ethyl Lactate 118.100
1.140
TMGa
114.830
1.103
GeCl
4
214.404
1.097
TMIn
159.930
1.120
Helium
4.003
1.630
WF6
297.830
1.075
Hydrogen
2.016
1.404
Nitrogen
28.010
1.399
Oxygen
32.000
1.395
POCl
3
153.33
1.168