Blackcrusader
Contributor
OK so like this. I use my Deco Planner to plan a dive but do not want to exceed NDL. The Deco Planner lets me know the NDL time for the gas used. So when planning make sure what gas mode the DC is in. 21% or say Nitrox 32% or even Nitrox 40% if you use that.
Don't be on a nitrox setting when you plan a dive on normal air. Easy mistake to make. Lets say I want to do a dive to take photo of a critter at 30m but do not want to go into deco. I can use the Deco Planner for this. It will show you NDL time limit.
So I take my photos and now have plenty of gas in the tank. Take an AL80 with 210 bar 11.1 x 210 gives me the liters in the tank.
let stake that at 2300 liters
Other threads tell you to to calculate gas both in metric and imperial measurements. Please read this thread. Take your time.
Al 80 vs HP100 useable amount of air
80 cf vs 100 those are the numbers but what is the difference in real life? an Al 80 holds 77 cf and I can only access 2000 of the 3000 psi, I stop at 1000 psi for safety a little more than the 600 psi stop because its harder to breath the low pressure air. So I am using 51 cf and leaving 26...
So I plan this dive for 20 minutes to 30 meters on nitrox 32%. NDL time is 24 minutes.
Great I used 805 liters. So for myself I can count around 2 bar per minute.
Now I ascend and think how much longer can I do this dive. Will I make it to an hour with say 750 psi or 50 bar left in the tank.
OK so lets say I want to end the dive with 300 liters of air. 2300 minus 805 for the first 20 minutes of my dive minus 300 liters.
So leaves me to use 1195 liters. But to play it a bit safer I say I have 1100 liters left for the rest of my multilevel dive using 2 bar per minute. Sounds all very confusing which it is so read the thread links lol
now at say my 2 bar per minute consumption rate I could do a rough calculation of the remaining dive time.
Article: Liters and Meters and Bars: OH MY!!!
You can view the page at http://www.scubaboard.com/forums/content.php?r=412-Liters-and-Meters-and-Bars-OH-MY!!!
Or I can just use my Cressi which does live real time calculation to 50 bar for me. Top right where it shows range is the time from current depth to 50 bar at current gas consumption average on the dive.
So in the screen shot I am at 17.4m depth, dive time of 54 minutes, I have 73 bar left... at top right where it says range it shows I have 11 minutes time left to 50 bar. So I easily make the 1 hour dive from the dive op and surface with 50 bar. or I could decide to ascend to 5 meters and extend the time to 50 bar by going shallow and using less air.
