[quote=jaap;82782]
Quote: (Originally Posted by
Tom Rose)
Monitor output is 50 mv for a CO2 level of 5% making it compatible with O2 cell displays. Power usage is 25 Milliamps
I have designed a retrofit package for any rebreather with over shoulder hoses.
quote]
Nice thing! Do you have any pics of the whole thing including the gasdrying parts?
I guess the output is proportional to the concentration of CO2? So that it reads in %-CO2?
Or is the output affected if the %-CO2 is constant but the pressure is changing?
The thing I'm after is that I guess a diver would like to have the display giving pCO2 or SEV-CO2 conc.
So is it also necessary to incorporate at pressure sensor to get an easy to interpret CO2-level reading?
A NDIR system "counts" the molecules of CO2 in the gas path....the greater the number of CO2 molecules the less signal to the detector....the number of molecules in the path is due to a combination of proportion of CO2 and pressure. Regardless, you cannot tolerate but so high a percentage of CO2 molecules in the gas mix reported as if it was at the surface.
Therefore it does not care about pressure or concentration. It just tells you the absolute amount of CO2 in the IR path.
Just like oxygen....pure oxygen at the surface is not a real problem to breath....but take that pure oxygen to 100 feet and we have a problem...houston control
We certainly do not want to breath CO2 levels of 5% at the surface or at 130 feet breath 1% CO2. Fortunatly properly working scrubbers keep the CO2 at lower and lower percentage as depth increases.
Hope this helps,
Tom