Principles / Modes Of Operation; Calculation Of Gas Concentration - CODEL Energy Tech 401 Installation, Operation And Maintenance Manual

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
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