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Instruction Manual
HASAxE-IM-HS
05/2006
Emerson Process Management GmbH & Co. OHG
Fig. 3-4 shows the mechanical design of an
pyro detector assembly:
Attached to the chopper are IR source (07) as
well as analysis cell (09) with signal detector
unit (filter cell 14 / 15) and pyroelectrical
detector with integrated pre amplifier (16).
Furthermore the chopper assembly contains
the filter aperture (04 / 05) limiting the IR light
to the required bandwidth.
The chopper assembly (03) is made of two
parts and contains an inner volume where the
stepper motor driven chopper wheel is placed.
This inner volume is sealed against ambience
by means of an o-ring to prevent ambient CO
2
from entering. This avoids pre absorption and
drift. An additional absorber is used to remove
CO
2
traces existent by diffusion.
Furthermore the chopper assembly contains a
light barrier to detect the chopper wheel
phasing. A temperature sensor (28) measures
the assemblies‘ temperature. This information
is used for the purpose of compensating
temperature effects.
The analysis cell is made of an aluminum tube
with two gas fittings. This simple design without
windows easily allows cleaning if the cell is
polluted.
The chopper windows and those at the filter
cell remain as only possibly polluted windows.
All of them are accessible once the analysis
cell is removed.
The filter cell (14 / 15) is made as two-tiered
conus system, which is optimized to focus the
beam to the active detector area.
High measuring ranges (up to 100 %) require
an adaptor cell (10): The analysis cell is in this
case the volume between output window of the
adaptor cell and input window of the filter cell ,
covered by a distance ring (08).
Photometer Assembly with Pyro Detector
3-1 Infrared (IR) and Ultraviolet (UV) Measurement