TOC EVOLUTION:
USER &
MAINTENANCE MANUAL
Page:
12/74
Instructions No.: 10844
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6 Measuring principle
The measurement of organic carbon, based on the cold oxidation principle, can be represented
as follows:
- Preparation of the sample
- Oxidation of organic matter
- Measurement of resulting CO2
6.1
Preparation of the sample
6.1.1
Sampling
The analyser is to be supplied automatically:
- By pumping into a tank, whose system will have been manufactured by the client in a suitable
manner (surface sampling type - for an uncharged sample in general),
- either from a fast loop, if a pressurised pipework has been provided (optional - uncharged / weakly
charged sample),
- or from an anti-clogging device, if the sample to be tested is collected in a pond or gutter,
(optional)
–
the charged sample.
For this last version, please consult us.
The sample collection/treatment system is used to store up to 100 µm of particles. A crusher is
added is necessary.
The sample and filter line is cleaned either by using the
“
Black Cleaning
”
technique (counter-current
cleaning), or with compressed air, on a case-by-case basis.
6.1.2
Removal of mineral carbon
The sample introduced into the analyser is acidified with sulphuric acid (or other acids according to
the configuration) in order to transform the mineral carbon into CO2. The stripping process is carried out
in hot conditions, which reduces the acid consumption (~ 1.5L/month) and accelerates the speed of
transformation into CO
2
.
The gas is then evacuated into the atmosphere or can be measured and displayed.
6.2
Oxidation of organic matter
For this operation, in order to achieve an efficiency equalling that of the combustion technique (800-
900°C), which nears 100%, we have implemented a UV source with a high radiating power inside a
reactor.
The sample is injected into the reactor when hot. The UV directly oxides the organic matter, which
transforms into CO
2
. Furthermore, the temperature inside the reactor increases in the presence of these
very powerful UVs and favours the oxidation.
A significantly reduced amount of oxidising reagent (~3L/month) is added in order to further reduce
the analysis time.