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2.2
2.2.1
Calculation of
Gas Concentration
Issue: A
Revision: 1
Date: 24/07/19
Principles
Operation
Gas levels are determined by measuring the absorption of infrared radiation,
transmitted through the flue gas, in a wave band sensitive to absorption by the
measurement gas. The EnergyTech 401 has two detectors; one measuring the
radiation directly to provide a live output, sensitive to the measurement gas,
while a second detector measuring the radiation after passing through a gas cell
filled with pure reference gas (CO), to provide a reference measurement,
completely unaffected by the measurement gas.
The basic expression from which the gas concentration in the gas is determined
is;
Y
=
Where
D1
=
D2
=
G
=
K
=
thus,
K
=
This parameter Y is then smoothed, linearised and compensated for effects of
path length and flue gas temperature, to produce a measurement of gas
concentration in the flue gas.
Ref: 100606
Section 2
General Description
/
Modes
G - K. D2/D1
the reference output from the detector
the live output from the detector
a scaling factor (16000 for CO)
a constant, known as the zero-correction
factor, set so that when there is zero
measurement gas in the duct, Y = 0
G.
D1 (0)
D2 (0)
of
Page: 17
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