Quote: (Originally Posted by joshhan2000)
1679.8 nm
Not clear why Electrogi is asking the question but as it is on a Rebreather forum, I would point out that 1679.8nm is not the absorption line that is detected in most CO2 sensors: lines in the 4 to 5micron range are used instead, with a reference usually around 3.8micron in a dual wavelength detector.
The following link gives a decent and simple summary, though it is not the sensor we use:
http://www.aegis-semi.com/products/d...ter_Sensor.pdf
Note that as well as CO2, the CO lines are quite close (4.7um), and it is possible to use either the same sensor or a sensor with separate filter section, to detect CO in the gas. However, this is not the best way to do it. Aktina Ltd have a very nice and superfast response CO and hydrocarbon detector, which apart from the power consumption, allows most contaminants in the breathing loop to be detected.
Pressure spectral spreading, and particularly spectral spreading due to inert gases (helium), are THE major issues. Only recently have these detectors achieved the 3% FSD accuracy required in EN14143:2003 in diving applications, though 10% accuracy has been available for 4 years. The scale is log scale anyway, so as far as CO2 monitoring goes, EN14143:2003 has done nothing except block safety featurings coming onto the market.
Cheers
Alex