Facts About Scuba Tanks

"Self-contained underwater breathing apparatus" is the definition of the popular water sport SCUBA. Humans are not able to explore the deep ocean for a great length of time and depth without the important scuba cylinder or tanks which hold compressed air. Most recreational divers rent air tanks from diving centers that are responsible for regularly inspecting and testing the quality of the tanks. Scuba tanks are available in a wide variety of shapes and sizes made of different metals, but they all provide the same crucial function.

  1. Metal Material

    • Steel and aluminum are the two most common metals; however, each has its own benefits and disadvantages. Steel is harder and heavier than aluminum, which makes it less likely to be damaged and tends to last longer. However, it is expensive and more prone to corrosion. Most dive shops use aluminum tanks, which are softer and more prone to dents but inexpensive and require less maintenance.

    Inspection Requirements

    • Air cylinders are required by law to be inspected every year and to receive hydrostatic testing every five years by professional technicians to ensure the quality of the tanks. These code requirements are updated on the surface of every air tank in a series of code. The first and second code states the regulatory agency and the material of the tank. The third marking on the first line states the service pressure, which may be as low as 1,500 psi or as high as 4,500 psi. A "+" sign may also be stenciled on steel tanks, which means the tank has been filled 10 percent above its service pressure. Aluminum tanks should never be filled above their service.

    Tank Size

    • The size of the tank a diver chooses is based on a variety of factors: the diver's physical size, size of his lungs, fitness level and the depth at which the air will be inhaled. Most dive rental tanks are 80 cubic feet to 100 cubic feet for longer dives. The tank capacity, for both steel and aluminum, is measured by finding how many cubic feet of air can be stored in a tank at the tank's pressure level. Generally, steel tanks have either a low pressure (2,400 psi) or high pressure (3,440); aluminum tanks usually have 3,000 psi.

    Nitrox Tanks

    • Some divers may choose to use enriched air nitrox (EAN) for longer and deeper dives. The EAN tanks have a higher oxygen and lower nitrogen concentration than normal air tanks. When diving, the higher the pressure is the more quickly the nitrogen will dissolve in the blood stream. Divers are required to slowly make their way up to the surface with a mandatory decompression stop to prevent decompression sickness. EAN tanks lengthen the no-decompression time which allows divers to dive longer at a deeper level than usual air tanks. Most rental shops provide pre-mixed tanks at 32 percent more oxygen.

    Pony Tanks

    • "Pony" tanks have become a popular accessory for many divers. The small tank straps to the normal-sized tank with its own regulator and gauge. These tanks are filled with enough air to provide a safe ascend to the surface.