Siemens ULTRAMAT 23 Series Equipment Manual page 26

Description
3.3 Function
form a Wheatstone bridge. The pulsating flow together with the dense arrangement of the
nickel grids causes a change in resistance. This leads to an offset in the bridge which is
proportional to the concentration of sample gas.
Note
Contamination of the analyzer chambers
The sample gases must be fed into the analyzers free of dust. Condensation should also be
prevented in the analyzer chambers. Therefore, the use of gas modified for the measuring task
is necessary in most application cases.
Furthermore, the ambient air of the sensor must not have large concentrations of the
components to be measured.
Device versions with a certificate for emission measurements have a calculated drift
compensation activated for the SO
>= 6 hours.
Ultraviolet measurement
1
2
3
This measuring principle is also based on the molecule-specific absorption of bands of ultraviolet
radiation using a double-beam photometer.
The light source is two light-emitting diodes (LEDs) based on AlGaN or InGaN semiconductors
(1). The two light sources are operated in alternating cycles for signal evaluation.
The ultraviolet radiation is collimated by one lens each and first passes through a beam splitter
(3), which generates two ray bundles of the same intensity (measuring and reference radiation).
The measuring ray bundle passes through the sample chamber (6), into which sample gas is
26
SO LED
2
NO LED
2
Beam splitter
component if the cycle time during AUTOCAL is set to
2
4 Measuring channel photodiode
5 Reference channel photodiode
6 Sample chamber
Equipment Manual, 04/2022, A5E37100388-012
ULTRAMAT 23