First Time Nitrox Diving
- Thread starter bdizzle
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No worries, didn't take it as critical, I appreciate the input.
Since you have your own analyzer, test it when the tank will be at the temperature you will be using it at... especially if you are right at your MOD - the mix will change at different temps. In addition to the computer help above, i always keep my computer in Nitrox mode. I just set it to 21% when not using it because sometimes a computer will either default back to an odd percentage, OR lock you out if you switch back and forth too many times between air and nitrox.... have fun!!
Tony how does the mix change, first time I think I have heard that?
I'm sorry, the way I wrote that came off incorrect. The mix inside the tank is the same, however analyzing the contents after a hot fill and then analyzing the results after the tank has severely cooled, or vice versa will result in a slightly different reading.
The monitor may provide a reading in "percent oxygen," but it is actually measuring the partial pressure of oxygen. Change the pressure, and the oxygen reading changes, too.
Changes in temperature will also affect the rate of the chemical reaction in the fuel cell and, consequently, the reading of the monitor. While nitrox analyzers typically have temperature-compensation circuitry, problems can arise when a cold monitor is suddenly taken into warm conditions or vice versa. Always allow your nitrox analyzer to reach ambient temperature and calibrate the monitor to a known standard, typically compressed air at 21 percent, before putting it into action.
The monitor may provide a reading in "percent oxygen," but it is actually measuring the partial pressure of oxygen. Change the pressure, and the oxygen reading changes, too.
Changes in temperature will also affect the rate of the chemical reaction in the fuel cell and, consequently, the reading of the monitor. While nitrox analyzers typically have temperature-compensation circuitry, problems can arise when a cold monitor is suddenly taken into warm conditions or vice versa. Always allow your nitrox analyzer to reach ambient temperature and calibrate the monitor to a known standard, typically compressed air at 21 percent, before putting it into action.
I have noticed changes when analyzing tanks in airconditioned areas compared to repeating outside when it is 40C.
Always use my own analyzer to check.
Last year in Jeddah, one dive operator was renting out Nitrox tanks without an analyzer to check the O2, dived on air that day.
Always use my own analyzer to check.
Last year in Jeddah, one dive operator was renting out Nitrox tanks without an analyzer to check the O2, dived on air that day.
I didn't read the whole post, only skimmed, but it seems like you're asking what you should set your pO2 to? I leave mine at 1.3, but depending on your mix and the depth that you plan to be diving you could set it to 1.4 and be fine
ianr33
Contributor
That's could be due to the humidity. (Probably more likely in Florida than Jeddah I'm guessing!!)
Ambient pressure will stay the same (1ATM) If half the gas molecules are water vapor then the O2 % will be lower.
Calibrating an O2 sensor from a known air tank (rather than waving it around on a humid day) is most accurate. (But I don't typically bother)
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