Need for air tank o2 analysis

[diverdoug1]

Mike, I only use my analyzer when it is calibrated to both room air AND 100% O2 (I realize that most don't have this type of equipment). The point I was attempting to make is that it is a bad idea to trust any single source for your calibration (in response to your concern of Nitrox being in your air sample tank). It is fine if you want to use an air scuba tank to calibrate your instument, but you should back it up by paying attention to what it is measuring as the ambient FIO2. If it is telling you the the air around you is only 15% O2, then you might have a calibration issue (like you calibrated with EAN.

 

[miketsp]

Mike, I only use my analyzer when it is calibrated to both room air AND 100% O2 (I realize that most don't have this type of equipment). The point I was attempting to make is that it is a bad idea to trust any single source for your calibration (in response to your concern of Nitrox being in your air sample tank). It is fine if you want to use an air scuba tank to calibrate your instument, but you should back it up by paying attention to what it is measuring as the ambient FIO2. If it is telling you the the air around you is only 15% O2, then you might have a calibration issue (like you calibrated with EAN.

The problem is that a large difference between free air and a cylinder is not unusual (for the reasons I mentioned) so the fact that the air cylinder may not have air is not the first thought that would come into my mind. However from now on, if I have any discrepancy between what the dive shop told me my EAN cylinder should have and what I measure after calibration, I will be sure to re-calibrate on a second air cylinder instead of re-checking the calibration on the same cylinder.