VALTRONICS MODEL 2008SDH-2AP
CARBON DIOXIDE MONITOR
INSTRUCTION MANUAL
Copyright 2017 VTI-Valtronics Inc.
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D. Gas Cell / Detector
(see Figure 2)
The board-mounted sensor contains a pulsed infrared source, a gas sample cell, optical
filter and detector. The detector provides an electronic signal that is converted into a gas
concentration value (voltage/current output).
Gas detection by the infrared method is based on the principle that most gases absorb
infrared energy at a characteristic frequency. In this instrument, a broadband infrared
source emits energy that is then filtered to produce a narrow range of frequencies
characteristic of the carbon dioxide absorption spectra. The band pass filter is chosen to
match a strong absorption band of carbon dioxide, while avoiding absorption bands from
other gases that may be present. Any carbon dioxide in the gas sample cell selectively
absorbs energy reaching the detector. This change in energy is detected, amplified and
sent to the signal-processing portion of the system.
FIGURE 2 (2008SDH-2AP Gas Cell / Detector)
