Carbon Dioxide; Ndir Measurement Of Co; Sensor Theory Of Operation - Teledyne T100 Instruction Manual

Teledyne ML - T100 UV Fluorescence SO2 Analyzer
9.3. CARBON DIOXIDE (CO

9.3.1. NDIR MEASUREMENT OF CO

) SENSOR THEORY OF OPERATION

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The CO sensor probe measures the concentration of carbon dioxde in the sample gas; a
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Logic PCA conditions the probe output and issues a 0-5 VDC signal to the analyzer's
CPU, which computes the CO
and CO _OFFSET recorded during calibration
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The CO sensor assembly itself does not have any serviceable parts and is enclosed in an
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insulated canister.
The optional CO sensor is a silicon based Non-Dispersive Infrared (NDIR) sensor. It
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uses a single-beam, dual wavelength measurement method.
An infrared source at one end of the measurement chamber emits IR radiation into the
sensor's measurement chamber where light at the 4.3 μm wavelength is partially
absorbed by any CO present. A special light filter called a Fabry-Perot Interferometer
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(FPI) is electronically tuned so that only light at the absorption wavelength of CO
allowed to pass and be detected by the sensor's IR detector.
A reference measurement is made by electronically shifting the filter band pass
wavelength so that no IR at the CO
IR Light
Source
Sample
In
Figure 9-8: CO
The sensor computes the ratio between the reference signal and the measurement signal
to determine the degree of light absorbed by CO
dual wavelength method the CO
ancillary effects like sensor aging and contamination.
06807A(DCNxxxx)
concentration by scaling the values of the CO
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absorption wavelength is let through.
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Sample
Out
Sensor Theory of Operation
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present in the sensor chamber. This
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measurement allows the instrument to compensate for
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Theory Of Operation
_SLOPE
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is
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IR
Detector
(NDIR)
Signal
Out
FPI
(Masure Phase)
Signal
Out
FPI
(Reference Phase)
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