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3-3
Instruction Manual
HASAxE-IM-HS
05/2006
Emerson Process Management GmbH & Co. OHG
3 Principles
3-1-2 Opto Pneumatic Measuring Principle
This high performance principle is used for IR
and UV measurements and utilizes a separated
analysis cell whose one side is passed by the
sample gas. The other side (reference side) is
either filled with an inert gas (e.g. nitrogen) or
passed by a reference gas stream, depending
on application.
Both sides of the cell are alternately irradiated
with IR (UV) light of same intensity, which
afterwards passes a filtering cell before it
arrives at the detector.
The opto pneumatical detector, which is used
instead of the pyroelectrical detector with the
IFC principle, converts the radiation from sam-
ple side and reference side into a voltage
signal proportional to the radiation intensity.
The pneumatical detector consists of a gas
filled absorption chamber and a compensation
chamber, both connected by a flow channel. A
micro flow detector is placed within this channel
to measure least flows.
compensation chamber
Fig. 3-2: Gas Detector Design Principle
gas filler
absorption chamber
flow channel
with
micro flow detector
CaF
2
window
3-1 Infrared (IR) and Ultraviolet (UV) Measurement