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joshhan2000 · 21st December 2005, 06:45

I was not talking about the deviation of the Pressure. There really is not much difference in that at all. I was talking about how IR work in detection of CO2. IR can only detect molecules that have a dipole moment. You can figure out the module by using symmetry operations theory. But needless to say CO2 has a dipole moment. Were O2 N2 He and H2 do not. This is what makes IR good at detecting CO2. But when you increase the pressure by 10 bars you have also decreased the space the gas occupies by 10 times. This decrease in space leads to formation of CO2 crystal structures. Although these crystal are quick forming and quick to fall apart they are still there. So when you use the 4500 nm wave length of light to activate the CO2 you will get a falsely high reading form the crystals and will not achieve the 97% accurate that we all want. I not saying that IR can not be adjusted using things like Fourier Transform or by doing a calibration scale but in the lab we just simply cut the gas pressure down. I know that last year when using IR to measure CO emission of cars it took 25 know samples to calibrate the IR to read acutely. IR is not a linear scale that we are all use to on the O2 sensors. It is polymeric and will take a lot of work to calibrate the scale properly.

21st December 2005, 06:45	#3 (permalink)
joshhan2000 New Member Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Dec 2005 Location: olympia wa usa Posts: 46	Re: Ir detection limit I was not talking about the deviation of the Pressure. There really is not much difference in that at all. I was talking about how IR work in detection of CO2. IR can only detect molecules that have a dipole moment. You can figure out the module by using symmetry operations theory. But needless to say CO2 has a dipole moment. Were O2 N2 He and H2 do not. This is what makes IR good at detecting CO2. But when you increase the pressure by 10 bars you have also decreased the space the gas occupies by 10 times. This decrease in space leads to formation of CO2 crystal structures. Although these crystal are quick forming and quick to fall apart they are still there. So when you use the 4500 nm wave length of light to activate the CO2 you will get a falsely high reading form the crystals and will not achieve the 97% accurate that we all want. I not saying that IR can not be adjusted using things like Fourier Transform or by doing a calibration scale but in the lab we just simply cut the gas pressure down. I know that last year when using IR to measure CO emission of cars it took 25 know samples to calibrate the IR to read acutely. IR is not a linear scale that we are all use to on the O2 sensors. It is polymeric and will take a lot of work to calibrate the scale properly. Last edited by joshhan2000 : 21st December 2005 at 11:12.
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