This is bothering me.
SCUBA tanks contain lots and lots of oxygen compressed to fit in the tank.
Question: why don’t those suckers float like all-get-out?! Yeah, they’re heavy… but THAT heavy?
If you imagine a balloon filled with the amount of air in one of those tanks… it would take a LOT of weight get it submerged.
I’m pretty sure the answer’s gonna be “Yes, the tanks are that heavy,” but geez…
Thanks!
-dietrologia
You wear weights when you dive…
Although there is a lot of oxygen in the tanks, it is under high pressure and therefore denser than if the same amount was put in a balloon. You could make lead float, if it was evaporated and used to inflate a very heat resistant balloon.
And they use weights. 8^)
Adding air to a fixed space won’t cause it to float, just the opposite. Air has mass. A full SCUBA tank has 200 times more air in it than an “empty” one but the same volume. In fact an aluminum tank will sink when full and float when empty. When you inflate a balloon it gets bigger, displacing more water.
It’s air in the tanks for sport divers - you can’t breathe straight O2 - at least not for long.
You wear weights when diving mainly because you are bouyant in the first place, and if you are diving somewhere like Northern California, you will be wearing a thick wet suit which REALLY makes you bouyant. Wearing a wet suit without anything else allows you to do a very good imitation of a cork.
You also wear a BCD (bouyancy control device) - basically an adjustable blow up vest connected to the tanks that you can use to help maintain neutral bouyancy. It’s also contributing some flotation.
[It’s air in the tanks for sport divers - you can’t breathe straight O2 - at least not for long.]
not having Nitrox training, I’m not sure about this but I believe you can breath O2 to a dept of 16ft without suffering O2 toxicity and no nitrogen to deal with.
If the weight of the water displaced by a object (bouyancy)is more than the weight of the object, it floats. So by putting more air (and mass,therefore weight) in a object of fixed volume it reaches a point where the weight overcomes the bouyancy and it sinks.
Yes, the tanks are heavier when full because the compressed air has mass.
In fact, some inexperienced divers have problems staying at depth as their tanks empty out and become more bouyant. For a number of reasons, every dive should end with a short safety stop for 3-5 minutes at 15 feet or so. Novice divers often have trouble keeping themselves at 15 feet during these stops because they were unprepared for the bouyancy of their nearly-empty tanks (and usually because they were underweighted at the beginning of the dive since their full tanks helped keep them down).