Carbondioxide analyzer

instrumentation

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Carbon dioxide analyzer

What is carbon dioxide analyzer?

The carbon dioxide analyzer is also referred to as CO2 analyzer, which is often used to detect and measure the amount of carbon dioxide in a sample of gas. These analyzers can be panel mounted using an adapter plate.

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This device uses a carbon dioxide sensor, in which the output from the sensor will be proportional to the measure of carbon dioxide. This signal is displayed in parts per million carbon dioxide on the led display.
How does carbondioxide analyser works?
The measurement and detection of carbondioxide is based on the absorption of Infrared radiation by carbondioxide molecules at certain wavelength.

The device will use high energy heated element to generate broadband IR light. This light is passed through a rotating gas filter wheel that causes the beam to alternately pass through a gas cell filled with a mixture of gases. The alteration occurs at a rate of 30 cycles/ sec and causes the beam to be modulated into the reference and measure pulses.

During the reference pulse, the carbondioxide strips the IF energy. As a result, a beam unaffected by carbondioxide is formed in the sample cell. During the measure pulse, the carbondioxide absorbs the IF energy. The beam then enters the folded mulltipass sample cell to achieve maximum sensitivity.

Finally, the beam strikes the detector which is a thermo-electrically cooled solid-state photoconductor. This detector along with its pre-amplifier and bias voltage supply converts the light signal into a modulated voltage signal. The detector output is demodulated to generate two voltages CO2 measure and CO2 reference. These voltages are proportional to the light intensity striking the detector during the measured pulse and reference pulse resp.

Let’s see a model

GFC7000 is an example. The typical sensor will look like the above image. This is mainly the science of spectroscopy. The technology of spectroscopy relies on the fact that the molecules will absorb light or electromagnetic energy at specific spectral regions depending on what the molecule is. For example, the absorption of IF radiation takes place at the wavelength near 4.2 microns.

This consist of a sample cell, two parabolic mirrors, two miniature mirrors, two glass windows, a chopper motor, CO2 filter wheel, an infrared source, infrared detector and pre-amp and electronic diplay.The temperature, pressure and relative humidity will affect the measurement.