George E. Cawthon wrote:
mawtg wrote:
does anybody know how a gas cylinder measuring 6" dia and 32" tall can
have 80 cu ft of gas? how is this figured?

The answer is that it can't. It can only hold
about 1/2 cubic foot (if I did the math
correctly). Doesn't matter what the gas is,
doesn't matter what the pressure is, it is always
the same volume because gases expand to fill the
volume of the container. The question is
illogical probably based on a statement that was
incomplete, or part of which was ignored in
stating the question.


Not quite. Your statement is incomplete as well. That .5 cubic foot that you
suggest only holds true at atmospheric pressure. If you compress the gas
within, you can hold virtually any amount up to the bursting pressure of the
tank. On 80 cf scuba cylinders which are only a little bigger than his example,
you'd charge them to about 200 atmospheres (3000 psi) to get the 80 cubic feet
packed in there. It is understood that the 80 cf measurement is what the
cylinder holds under pressure, not empty.

AGA Divator used to make twin 40 cf systems that required them to be pumped up
to 4400 psi. Now that is one hell of a lot of pressure. They were little
things that fit closely to your back but they were ungodly expensive and most
dive shops couldn't fill them. But they packed the same 80cf as the larger
cylinders.


--
Mortimer Schnerd, RN

VE