mru SWG100 BIOEX, User Manual, Page: 16 / 150

MRU GmbH SWG 100 BIO Ex User Manual
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3.2. Principle of operation
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Sample gas from one or more sampling points is fed into the analyzer by
dedicated 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 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 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 the sensors with fresh (ambient) air for re-adjust the zero point.