multi EA 5100
Carbon analysis with the TOC module 5100
87
12
Carbon analysis with the TOC module 5100
12.1 Function and design
12.1.1 Function and measuring principle
The detection module contains a wide-range NDIR detector. Expansion of the basic
module with the detection module allow determination of the following sum parame-
ters:
Sum parameters
Samples
Basic module configuration
TC
Organic liquids, solids and
gases
Vertical/horizontal opera-
tion
EC/OC
Elemental and organically
bound carbon from par-
ticulate emissions (fine
particulate matter, diesel
engine exhaust, smoke
gas
Horizontal operation
with:
¡
Special combustion
tube for EC/OC deter-
mination
TC, TOC, NPOC, TIC
Water samples
Vertical operation with:
¡
TOC combustion tube
¡
Condensation coil
Carbon dioxide (CO
2
) and water (H
2
O) is created during thermal oxidation of the sam-
ples in the basic module. The gas mixture is dried and transferred to the NDIR detector.
R + O
2
→ CO
2
+ H
2
O
R: Hydrocarbon
The radiation sensor used in the TOC module is CO
2
-sensitive. The double bond between
carbon (C) and oxygen(O) has a specific absorption range in the infrared wavelength
band.
If a ray of light is projected through a cuvette arrangement, the CO
2
content in the mea-
suring gas absorbs a proportion of the total radiation proportional to the CO
2
concentra-
tion.
A proportion of the water sample is dosed manually into the TIC reactor to determine
the inorganically bound carbon (TIC) content. The sample reacts with phosphoric acid in
the TIC reactor. This creates CO
2
, which is determined via the NDIR detector.
The detection module determines the CO
2
concentration multiple times per second and
generates an integral over time from the signals. The integral is proportional to the car-
bon concentration in the sample.
12.1.2 Design
All components of the module to be operated or serviced by the user can be access via
the door on the front of the module.
The module consists of the following main components:
¡
TIC condenser unit (with TIC reactor, gas-liquid separator, measuring gas dryer)
¡
Condensate pump
¡
Halogen trap and water traps for drying and cleaning the measuring gas.
¡
NDIR detector (in the rear part of the detector)
¡
Indicator and control elements, connections
