Infrared
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Infrared Gas Sensors
Infrared Gas Sensors exploit the property that many gases absorb radiation in the 2-14 micron, infrared region of the spectrum. These spectral absorbances show features which may be regarded as 'fingerprints' to identify the gases and enable their concentrations to be deduced.
The sensor bodies contain an infrared source and infrared detectors inside a compact and combined gas cavity/ optical cell. The detectors have infrared bandpass filters placed in front, which tune them to the specific gases to be sensed.
When the specific gas enters the cavity it is registered as a change in detector signal. The magnitude of this change is related to the concentration of that gas via a simple exponential formula.
By utilising different infrared filters a range of gases can be sensed and discriminated with these devices. In cases where spectral lines overlap, then an individual sensor may show cross sensitivities to a gas range.
Infrared gas sensors are very robust devices not affected by contact with a harsh chemical environment. Any changes in ambient conditions such as temperature are compensated for in software.
Their dimensions and power requirements are compatible with and complementary to pellistor gas sensors.
Infra-red Gas Sensors for Hydrocarbons or CO2
After over thirty years of successful manufacture of pellistor-based flammable gas sensors, the range of Non-Dispersive Infra-red (NDIR) gas sensors represents the first of many diversifications into other areas of gas sensor technology by us.