Principle Of Operation - mru SWG100 BIOEX User Manual

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Principle of operation

Sample gas from one or more sampling points is fed into the analyzer by dedicated
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ports. Internally mounted electric valves select one point at a time to feed sample gas
to the analysis unit.
The instrument is equipped with a non-dispersive infrared (NDIR) bench for analysis of
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CO2 and CH4. Two separate infrared detectors for each CO2 and CH4 are included,
each operating with a different optical path length and stabilized by referring to a
reference detector. The IR source is a highly efficient and stable IR emitter, pulsed at a
frequency of several Hertz. By design NDIR technique offers good stability and
selectivity together with long life time of sensor (only limited by corrosion or dust, which
can be prevented or removed by regular servicing the instrument).
The instrument is optionally equipped with a number of electro-chemical sensors ECS
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in order to detect gas components like oxygen O2 or H2S. Those sensors offer a
reliable and effective way to detect the target gases. They are typically of limited life
time (several years) but may be easily replaced once the end-of-life is reached.
In regular time intervals (user settable), the instrument automatically switches to purge
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the sensors with fresh (ambient) air for re-adjust the zero point.
SWG100 BIOGAS User Manual
MRU GmbH, D-74172 Neckarsulm