Diving tanks stand directly between life and death for divers; these apparatuses are the only source of oxygen for divers when they're finally out in the deep blue. The relative importance of diving tanks has made the purchasing process trickier- there are now far too many brands, too many manufacturers to choose from.
In the past, companies were producing scuba diving tanks mostly for governments around the world: for the marines, the naval reserves and the military. Orders were always by bulk, and specifications were in accord with what the institutions needed. Smaller manufacturers focused on the steadily growing niche of underwater researchers who periodically needed new scuba dive tanks.
Eventually, the activity became a full blown sport- and people were now doing it for fun. Manufacturers then had to radically redesign some of their lines to suit the needs of a newly emerging market.
Often, the new buyers are confused in choosing between two types of dive cylinders: one type, produced using age-old steel, and a second type, produced with the more familiar material, aluminum. What is it that differentiates the two types of diving tanks, based on performance, anyway?
Make no mistake, both steel diving tanks and aluminum scuba diving cylinders experience corrosion when exposed to the chilly brine. Both diving tanks produce their own variations of rust- both are quite capable of eating through the metal if the tanks are left to their own devices.
What about buoyancy then, you might ask. Well, steel is denser than aluminum, which means that gram per gram, it takes far less steel to complete a tank that is fit to be pressurized and used underwater. This makes steel diving tanks more buoyant when you use one in the water.
What kind of weight difference are we looking at here? An aluminum diving tank would weight seventeen percent more than its steel counterpart; which means that if a steel tank weight around thirty pounds, the aluminum counterpart would weight thirty five pounds at least.
As for lifespan, records show that the properly maintained steel scuba diving tanks can last for more than forty years. The aluminum counterparts reach the end of the road in about fifteen years. After fifteen years, specialty repair shops and refilling stations no longer allow a diver to fill an aluminum tank.
Experience divers often note that aluminum diving cylinders become lighter and lighter as the oxygen is displaced and consumed by the diver. This makes it harder for the diver to maintain a consistent weight that allows him to navigate underwater.
Steel diving tanks on the other hand, due to their mass, allow the diver to be weighted sufficiently before and after a dive. Manufacturers have tried to remedy this problem by introducing newer lines of aluminum tanks that have higher pressure- however; this line has not really caught up with the more "vintage" line of steel diving tanks.
What makes aluminum diving tanks an option, still? The answer might surprise you: it's the price. Aluminum diving tanks are cheaper than steel diving tanks; which makes them an easy choice for divers who have limited budgets.