Why Does a Scuba Tank Not Float?

Why Does a Scuba Tank Not Float?
Scuba diving can be an intriguing sport, but it is important to understand all of the aspects of it before you jump in the water with air tanks strapped to your back. Although a scuba tank will sink in the water whether it is empty or full of air, it will sink faster when it is full.


Scuba tanks are metal, which makes them heavy. This is intentional; heavy tanks help divers sink.


Air has weight, and if you fill a scuba tank with air, it will get heavier. A tank that holds 80 cubic feet of air is six pounds heavier when it is full than when it is empty.


Whether objects sink or float in water depends on their buoyancy. Objects such as balloons, inner tubes or rubber rafts will float if filled with air and put in the water. The air increases the volume of these expandable items so there is less weight per square inch, making them lighter than water.


Because scuba tanks don't expand, the air inside them doesn't add to their surface area or make them more buoyant.


As a diver breathes the air inside the tanks, they become lighter. The diver's buoyancy, combined with the decreased air weight in the tanks, makes it harder for the diver to stay under water as the tank gets lighter.

Article Written By Maria Tussing

A freelancer from South Dakota, Maria Tussing has been writing since 2000. She has been published in "Family Fish & Game," "Wondertime," "Today's Horse" and "Cattle Business Weekly," among other publications. Tussing holds a Bachelor of Science in journalism from Chadron State College.

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