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Welcome to Dive Gear Reviews, a comprehensive guide to scuba diving equipment. Scuba diving is an expensive pursuit, so looking up reviews for a particular article of equipment is a wise precaution before investing any hard-earned money in it. However, consumer reviews may or may not be written by an experienced diver, and magazine reviews could be suspect due to the advertising ties of the publication in question. Dive Gear Reviews provides cross-referenced reviews assembled by an expert, making it possible to see at a glance what multiple sources said about a particular piece of scuba equipment. If one magazine loved a scuba regulator or a dive computer, but the consumers hated it, that information will be found here.
15
June

Aluminum vs. Carbon vs. Steel Scuba Tanks

Written by Dive Gear Reviews Editor. Comments Off on Aluminum vs. Carbon vs. Steel Scuba Tanks Posted in: Dive Gear Tips, Other Accessories, Scuba Product Guides
Scuba tanks

A mix of scuba tanks (Credit: Wikimedia Commons)

For decades, divers shopping for their own air cylinder(s) have had two basic choices: aluminum or steel. Carbon fiber is a relative newcomer to scuba tanks, despite the fact that material has been used in high performance manufacturing sectors for many years. The old aluminum vs. steel debate is already out of date, and will only become more irrelevant as carbon fiber tanks become more widespread. The new issue for air tanks is whether to go aluminum, carbon or steel.

Aluminum Scuba Tanks: Most tanks on the market or encountered at dive shops are made of aluminum. On the plus side, aluminum tanks are the cheapest tanks out there, and they are more resistant corrosion than steel.

The drawbacks about aluminum all stem from the simple fact that aluminum is a relatively soft metal. In many applications, aluminum is chosen because it is lighter than steel, but in such applications the softness of aluminum is not an important issue. A scuba tank must withstand over a ton of pressure per square inch, however, so an aluminum cylinder must be thicker to compensate for its softness. Despite its reputation for lightness, this makes an aluminum tank heavier than its steel counterpart.

Paradoxically, aluminum tanks are also more buoyant than steel tanks, because aluminum is less dense. As a result, the typical aluminum tank becomes more buoyant over the course of a dive, as the specific density of the tank and its contents drops. This is neither a positive or a negative, especially since most divers are used to that shift, because aluminum tanks are so commonplace in the diving industry.

The softness of aluminum also makes it prone to stress failures, in basically the same way stress cracks form in airplane fuselages and panels. Aluminum tanks therefore typically last for only about 15 years under regular use, and overfilling will rapidly increase the wear and tear on these tanks.

Carbon Fiber Scuba Tanks: Carbon fiber is chosen for high performance manufacturing because it is incredibly strong, yet also very light at the same time. For scuba tanks, carbon fiber wins in every category except cost. At any given volume, carbon fiber air cylinders will be the most expensive option out there. For that high cost, you get a tank that is corrosion-proof, lighter than steel, and stronger than steel. As a rule, a given carbon fiber tank will have a higher psi rating than its equivalent in steel, and weigh about a third as much. If you can afford it, carbon fiber is the way to go.

Steel Scuba Tanks: Steel air cylinders are tougher and lighter than aluminum. You can overfill steel to a certain extent without seriously degrading the integrity of the tank, and on average a regularly used steel scuba tank lasts for 40 years. They are negatively buoyant in the water, and become less so as the gas in the tank is expended and the specific density changes. Like aluminum, that is neither a pro or a con, but merely a factor to be compensated for.

The main drawback of steel tanks is the rust. Caring for a steel tank is just like caring for any other part of your kit that is made from steel, in that a simple freshwater rinse after the dive is not enough to fight off corrosion. The tank must retain a solid, complete coat of enamel if it is to be adequately protected. Over the lifetime of a tank, that means repainting it several times.