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how to choose your scuba tank?

A scuba tank is a pressurized cylinder used by divers to breathe while they are under water. It usually contains oxygen, air, or a specially made gas known as nitrox. Diving tanks vary in terms of length, capacity, material and finish. It is very important to choose a tank that can efficiently meet all your diving needs. These are some of the most vital factors to consider when selecting a scuba tank.

Material
Scuba tanks are made of either aluminum or steel. Steel has more strength and ductility than aluminium. Therefore, for the same gas capacity, a steel tank will weigh less than an aluminium tank and offer better buoyancy. For instance, an 80 cubic-foot scuba tank made of aluminum weighs about 35 lbs but a steel tank of the same capacity weighs 30 lbs. So if you want a lightweight tank, you should opt for steel instead of aluminium.

Service life is another characteristic that needs to be considered when selecting tank material. Steel offers longer service life than aluminium. Its useful life is said to be about 40 years. The service life of an aluminium tank is usually about 10 years shorter. That is why some dive shops will not fill up an aluminium tank that is over 25 years old. However, aluminium tanks are cheaper than their steel counterparts. So if you are on a budget, and you only need a tank for sport and recreational diving, you could make do with an aluminium tank.

Volume and Pressure
The volume of a scuba tank is measured in cubic-feet. For sport diving, you may choose the frequently used Aluminum 80 tank (AL80) which holds 77 cubic-feet of air at a pressure of 3000 psi. But you must note that the buoyancy of the tank increases as it gets empty so may need additional weight at the beginning of the dive. If you don't need as much air in your tank, you may opt for the Aluminum 63 (AL63). This tank is lighter, smaller and it has better buoyancy characteristics. But if you usually run out of gas before you finish your dive, you should choose a larger tank such as the high pressure steel (HP100). It will provide a pressure of about 3442 psi.

Tank Dimensions
The popular AL80 has a length of 26 inches. This length is usually long and a bit uncomfortable for many people. That is why the HP100 steel tank which has a length of 25 inches is prefered by some sports divers. Those who have a very small stature should consider using the HP80 or AL63. These tanks both have a length of 21 inches. Only those who are above six feet in height will enjoy diving with the HP120 or the HP133 whose height is over 28 inches.

Paint and Finish
The paint or finish of the tank you buy is important because it directly affects its ability to resist corrosion in salty sea water. Aluminum tanks are sold with various kinds of finish including brush finish, coated and shot blast. The brush finish aluminum provides better protection against corrosion than the painted tanks. Steel tanks are galvanized with zinc to resist rust. However, the best way to prolong the life any scuba tank is through proper care. Ensure that your tank is rinsed in fresh water and that the boots are removed after use.

Conclusion
When you are buying a tank for long term use, you would be better off with a steel tank because of its buoyancy characteristics and longer service life. Also, a high pressure tank that can be under-filled to meet your needs may offer better service than a smaller tank.