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Employment
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A compact, reliable,
and interference-free means to monitor water vapor concentration.
APPLICATIONS:
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Atmospheric Research: in-situ monitoring of tropospheric water vapor, either aerial vehicle or ground-based.
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Ambient Air Monitor: monitoring of humidity in the preparation of
food products, pharmaceuticals, photographic film, textiles, etc.
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Process Stream Monitor: monitoring of humidity in pipelines, flow
ducts, gas lines, etc.
ADVANTAGES:
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Continuous detection of water vapor concentrations
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Remote fiber optic coupling to measurement cell
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Stable and repeatable calibration
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Optical detection method inherently insensitive to interference
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Fast response time
STATUS: Concept
successfully demonstrated and prototype developed.
Seeking
partner for production model development.
PATENT: U.S.
Patent Number 5,760,895 (issued June 2, 1998).
SPECIFICATIONS:
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Measurement
Specifications
Temperature Range:
250-315 K
Pressure Range:
200-1200 mb
0.3-1.2 atm.
Sensitivity:
20 ppmv (at 1 Hz)
-55 °C Dew Point (1.0 atm.)
-65 °C Dew Point (0.3 atm.)
Time Response:
0.10 sec (0.01 possible)
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Operating Principle
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Water vapor concentrations are measured
using the optical absorption of a Zeeman-split emission line of an argon
discharge lamp. When a longitudinal magnetic field of the proper magnitude
is used to split the emission line, two components of opposite circular
polarization are produced: one coincident and one off-resonance with respect
to a water vapor absorption line at 10,687.36 cm-1 . Differential
absorption is directly measured by alternately selecting the polarization
of the light which is allowed to propagate down the optical path into a
multi-pass absorption cell. Water vapor concentration measurements can
be obtained over a range of over three orders of magnitude (~0.002-3.0%).
The monitor acts directly as a mixing ratio (mole fraction) sensor (within
±10%) over a pressure range of 0.3 -1.2 atmospheres.
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Instrument Characteristics
Electronics Module
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Weight:
Size:
Power:
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5 kg
45 x15 x15 cm (WxHxD) Rack Mount Compatible.
5-20 Watts depending on whether optical cell mirrors are heated.
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Optical Cell
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Weight:
Size:
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5 kg
30x10x10 cm (Depends on Mounting Arrangements)
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For more information about ARI Products or R&D Services contact:
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