Comment by esaym
9 years ago
>"so its unlike bowel gas analysis was a high priority in the specs"
Classic :)
After digging through ebay and google images for awhile, I finally found one of the two different units that we used: http://www.equipcoservices.com/sales/rae/multirae_plus.html
That one actually has, at least what sounds like, a built in aquarium pump that actually draws air into the unit.
The other style we used seemed to be completely digital. It made no noise and the main unit was big and bulky. The sensor plugged into it with long wires and the sensor it self was just a big heavy plastic cube. On one side it had a screen and behind the screen was just what looked like metal. As if it could sense gases through metal or something, dunno.
And I don't know which model I was using at the time of my "experiment"
I was motivated to bottom up research vs your top down and apparently technology has advanced and the cool kids these days are using obscure semiconductors that drop in resistance as reductive (as opposed to oxidative) gases adsorb on the surface, then periodically they heat up and cook off the adsorbed stuff (otherwise they'd be permanent total dosage sensors).
http://www.ewinsen.com/Admin/uploadfile/201209/2012916105693...
It ends up being the same argument on a high level that for both operational and practical reasons the sensors usually respond to anything that burns / reduces in the presence of oxygen regardless of specific chemistry and design.