EL3000
CONTINUOUS GAS ANALYZERS | OI/EL3000-EN REV. D
139
Fidas24 – Conversion of concentration data
Various units for concentration details
When measuring organic carbon compounds (total C) the
concentration is indicated in various units.
The most important units are:
• mg C/m
3
(e.g. for measurements in accordance with
17 BImSchV)
• mg C
n
H
m
/m
3
• ppm C
n
H
m
(e.g. for measurements in accordance with
Federal German Regulations on Air Purity, details on test
gas cylinders)
• ppm C1 (for THC or methane CH
4
)
Examples for the conversion of units and concentration
details
Conversion of ppm in mg C
n
H
m
/m
3
Conversion of ppm in mg C/m
3
Conversion ppm ® ppm C1
Example 1
The analyzer module has a measuring range of 0 to 50 mg C/m
3
.
As a test gas, propane (C
3
H
8
) in N
2
or in air is used.
What is the maximum test gas concentration in ppm or mg/m
3
so that the measuring range is not up-scaled?
Example 2
f a test gas other than propane is used, its response factor (see
Fidas24 – Response factors and other relevant variables
page 138) must be considered.
What is the maximum test gas concentration in ppm or mg/m
3
if
methane (CH
4
) is used?
The response factor for methane is Rf
CH
4
= 1.13; i.e. the measured
value display is too great by this factor.
In order to determine the maximum test gas concentration to
avoid exceeding the measuring range, the measured value
display must be divided by the response factor.
A test gas cylinder with approx. 80 ppm CH
4
has been ordered.
The test gas concentration in the test gas cylinder is
81.2 ppm CH
4
in accordance with the certificate.
This is equivalent to a concentration of
Considering the response factor, the indication should be
adjusted to
.
