Why yes, I do plan ascents... but not at 10psi/ft. Since air consumption varies with depth, I like to plan for what I typically use, with a little gravy.
Let's say I want to arrive at the 15 foot safety stop with 700 psi, on a 110 foot dive. At 30fpm, it'll take me 190 seconds, or just over three minutes, to make the ascent, with an average depth of a bit over 60 feet. I'll round it up to 66 so I can use nice round numbers in my calculations... 3 ATM.
Let's say my SCR is 25 psi/min for the tank I'm using, so my average consumption for the ascent will be 3 ATM x 25 psi/min x 3.2 minutes, or 240 psi. Let's make it 300 for a little gravy, so I need to start up at 1000psi.
Rick
