spitfiremac
New
Want to run something by the community...
I've been thinking about those little 3 cu ft. bottles and if they have any legitimate use at all in actual SCUBA, whether it be rec or beyond. General consensus is that anything smaller than a 19 cu ft pony bottle absolutely doesn't given proper safety procedure, buddy protocol, on and on.
I generally agree with this assessment. Spare air may only be for free divers/snorkelers, BUT there is one case that I think is worth mentioning.
In the case of a SCUBA emergency, two divers sharing one tank, depending on max depths and dive times before the OOA situation, stressed air consumption, etc, etc, Spare Air could be usable in the very limited context of ENABLING A PROPER SAFETY STOP at 15 ft by extending the air margin, and thereby avoiding a whole host of other issues on the surface.
Here are my calculations:
.5L x 3,000 psi (compression) / 14.7 psi (atmo pressure) =
102L (compressed air) in a Spare Air or SMACO bottle
102L = 3.6 cu ft of compressed air in said bottles
3,000 psi = 206.84 bar in bottles (for calculating SAC rate, which I did online here)
at a 22.98 L/min SAC rate (this is a baseline, not accounting for elevated breathing rates)
...that's (102L) / (22.98 L/min) = 4.43 min of air at a safety stop depth of 15 ft
At many rec depths, that could enable the completion of a safe ascent without the prospect of DCS for one or two people...
that being said, it has to be noted that this is if the slim Spare Air is ONLY looked at as a safety stop enabler or safety stop finisher... much like the altitude auto-deploy on a reserve parachute container, something no plane jumper in their right mind (absent product testers) would rely on for anything but primary and reserve pull-chord malfunction or unconscious freefall.
As far as using it to ascend, hey, if the situation is that bad at depth all bets are off, but you're not going to care about anything but air at that point. Thinking of this as a little bit of margin at 15 ft seems to me to be the only legit rec diving use of this, but not a bad one at all for the cost of a slim bottle and 2 extra pounds on land.
Thoughts?
I've been thinking about those little 3 cu ft. bottles and if they have any legitimate use at all in actual SCUBA, whether it be rec or beyond. General consensus is that anything smaller than a 19 cu ft pony bottle absolutely doesn't given proper safety procedure, buddy protocol, on and on.
I generally agree with this assessment. Spare air may only be for free divers/snorkelers, BUT there is one case that I think is worth mentioning.
In the case of a SCUBA emergency, two divers sharing one tank, depending on max depths and dive times before the OOA situation, stressed air consumption, etc, etc, Spare Air could be usable in the very limited context of ENABLING A PROPER SAFETY STOP at 15 ft by extending the air margin, and thereby avoiding a whole host of other issues on the surface.
Here are my calculations:
.5L x 3,000 psi (compression) / 14.7 psi (atmo pressure) =
102L (compressed air) in a Spare Air or SMACO bottle
102L = 3.6 cu ft of compressed air in said bottles
3,000 psi = 206.84 bar in bottles (for calculating SAC rate, which I did online here)
at a 22.98 L/min SAC rate (this is a baseline, not accounting for elevated breathing rates)
...that's (102L) / (22.98 L/min) = 4.43 min of air at a safety stop depth of 15 ft
At many rec depths, that could enable the completion of a safe ascent without the prospect of DCS for one or two people...
that being said, it has to be noted that this is if the slim Spare Air is ONLY looked at as a safety stop enabler or safety stop finisher... much like the altitude auto-deploy on a reserve parachute container, something no plane jumper in their right mind (absent product testers) would rely on for anything but primary and reserve pull-chord malfunction or unconscious freefall.
As far as using it to ascend, hey, if the situation is that bad at depth all bets are off, but you're not going to care about anything but air at that point. Thinking of this as a little bit of margin at 15 ft seems to me to be the only legit rec diving use of this, but not a bad one at all for the cost of a slim bottle and 2 extra pounds on land.
Thoughts?
