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Steel Tanks - Steel has
a higher density rate than aluminum, which allows the tank to be negatively
buoyant when your dive is completed. Steel tanks are available either in high
pressure (HP) or low pressure (LP). High pressure tanks are smaller and contain
a higher volume of air, and also require a regulator set up for DIN. A HP 100 is
slightly smaller than an AL 80. LP tanks are much easier to fill, but are also
quite large for the volume of air that they hold. |
The difference between Pressure & Volume - It should be noted
that the pressure of a tank is not a measure of the size or volume
of a tank. For example, most aluminum tanks, from the smallest 6 cuft pony bottle to an 80
cuft tank, have a fill pressure of 3000 psi. For a 6 cuft bottle, this means at 3000 psi
the tank contains 6 cuft of air. For an 80 cuft bottle this means at 3000 psi the tank
contains 80 cuft of air. Tanks come in a variety of combinations of volumes and fill
pressures but the cubic foot (cuft) volume is the measure of how much air a
tank holds. |
Valves - A K-valve, which comes on all
aluminum tanks and low pressure steel tanks, do nothing other than release or
stop the flow of air from the cylinder. |
DIN valve - These valves are used on all high pressure tanks - 3300 PSI and above. Regulators used on
HP tanks require that your regulator be converted to DIN. |