Gas Calculators

Warning:

Results from these calculators are not verified. Neither the author nor this website are liable for any loss, damage, or injury, including death, which may result from engaging in either scuba diving, snorkeling, or any of the activities mentioned within this site. These tools and calculators are provided for educational and convenience purposes only and should not be used for planning or conducting actual dives.

Nitrox Mix Calculator


Mix (FO2) Depth PO2 EAD

%

fsw

ATA

fsw



PN2: ATA


  • For Best Mix: input Depth and desired PO2
  • For Maximum Operating Depth: input Mix and desired PO2
  • PO2s above 1.4 - 1.6 are considered to be dangerous
  • PN2s above 3.2 - 4.0 are considered to be narcotic


NOAA Recommended Maximum Oxygen Exposures
( Central Nervous System Oxygen Toxicity )

PO2 single
exposure
24 hour
exposure
ATA minutes % per
minute
minutes % per
minute
0.6 720 0.139 720 0.139
0.8 450 0.222 450 0.222
1.0 300 0.333 300 0.333
1.2 210 0.476 240 0.417
1.4 150 0.667 180 0.556
1.6 45 2.222 150 0.667

Sea Level Standard Pressure:

1 atmosphere = 14.696 psia
= 29.92 inches Hg
= 33.831 ft water ( at 60°F )
= 0 ft altitude

Nitrox Fill Calculator


Current Fill %O2 at psi
Fill Mix %O2 Nitrox, balance: air
Nitrox + Air psi Nitrox + psi air
Target Fill % O2 at psi


Gas Consumption Calculator


SAC Depth Time Volume

cft/min

fsw

min.

cft



Tank Temperature / Pressure


Starting
Temperature
Starting
Pressure
Ending
Temperature
Ending
Pressure

deg F

psig

deg F

psig



Common Conversions


Metric Units

Proper Units

deg C deg F
meters feet
Bar psi
kilograms pounds
grams ounces
liters cubic feet
kilowatts horsepower




The proper way to fill a scuba cylinder is very slowly so that the heat generated by the filling process can be bled away as it happens, and the tank does not become overheated. That's a great theory, but in real life, nobody does it that way. Most tanks are "hot-filled", that is to say, that they are filled too fast to prevent them from heating up during the process. If they are filled directly off a compressor, then they will receive a very hot fill. You would be surprised how warm the surface of a tank can get. This is not much of a safety issue, though, as it is well within the thermal limits of the material, either aluminum or steel.

The real issue here is that eventually ( after a few hours ) the tank will cool down, and as it does, the air inside will contract, and the pressure will drop. This typically results in about a 10% loss of pressure. At this point, you could top it off to the rated pressure again and have a truly full tank. Most of the time that's not an option. Therefore, if the shop hot-fills your tank to 3000, you will end up with 2700. To get 3000, you need to fill the tank to about 3300. While this is verboten, it is well within the 5/3 overpressure of the hydro test, and realistically there is no danger. The slight overpressure may wear out your o-rings a little faster, but o-rings are cheap - get a dozen of them at the hardware store for a buck.