Emerson MicroCEM - Manual (Page 19)

Instruction Manual
748467-A
January 2002
Rosemount Analytical Inc. A Division of Emerson Process Management Description and Specifications 1-5
Model MicroCEM
Overall NDIR Method
In the case of dual-channel analyzers, the
broadband emission from two infrared
sources pass through the chopper wheel.
In the case of the Interference Filter Cor-
relation (IFC) method, the infrared radia-
tion then passes through combinations of
interference filters. In the case of the
opto-pneumatic method, the infrared ra-
diation passes through an optical filter
depending on the application and need for
reduction of influences. Then the infrared
radiation enters the analysis cells from
which it is focused by filter cells onto the
corresponding detector. The preamplifier
detector output signal is then converted
into the analytical results expressed di-
rectly in the appropriate physical concen-
tration units such as percent volume,
ppm, mg/Nm
3 , etc. This is shown in Fig-
ure 1-3.
Figure 1-3. Overall NDIR Method
MOTOR
Adapter Cell
(high measuring range)
Light Source
Chopper Blade
Duplex Filter Disc
Analysis Cell
(measuring side)
Analysis Cell
(reference side)
Filter Cell
Gas Detector
Preamplifier
Chopper Blade
Analysis Cell
(undivided)
Filter Cell
Preamplifier
Pyroelectric Detector
(solid-state detector)