Posted by Northcoast_diver on August 23, 2004 at 11:31:08:
In Reply to: Re: 19cu/ft pony bottle bottom times posted by Ross-O on August 23, 2004 at 10:42:45:
Just use 1 cu ft per min as your consumption rate, and you can easily comprehend the following:
At the surface, 19 cu ft would last 19 mins.
At 33 fsw, 19 cu ft would last 9 mins.
At 99 fsw, 19 cu ft would last 4 mins.
To ascend from 99 ft properly would take you 3 mins. This would consume about 6 cu ft of your bottle, about 1/3. That also tells you that the smallest bottle you could effectively get to the surface with from 99 ft, without stopping at 15 ft, would be a 6 cu ft bottle. However the smallest bottle that I would ever recommend for dives to 99 ft would be at least twice that volume.
With your 19 cu ft bottle, however, that would leave you with 13 cu ft with which to do a safety stop at 15 ft, after your ascent. You could wait 8 mins at 15 ft with that much gas, at 1 cu ft per min.
You should have plenty of extra air, with a 19 cu ft bottle. Although you do not have time to dink around while using it either.
Most normal RMVs are in the 0.5 to 0.75 range. But when something goes wrong, you normally would breathe more. That is why I used 1 cu ft per min in the examples. Plus the calculations are easier that way.
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