On Tue, 13 Jan 2004 00:51:21 -0600, Richard J Kinch wrote:
Gary Coffman writes:

P is proportional to n/V.

Not for adiabatic conditions, which is what practical compressed air
systems most resemble:

p1 * v1^(5/3) = p2 * v2^(5/3)

not:

p1 * v1 = p2 * v2.

Irrelevant. PV=nRT. With RT relatively constant,
PV=kn, or P=kn/V, and ignoring k, P is proportional
to n/V just as I said.

So if you release half as much air to get 50 PSI downstream
of the regulator, then the remainder does stay in the tank.

You confuse the p*v energy with the "maximum attainable work".

No I don't, but you seem hopelessly lost.

A reservoir of given volume and pressure is not equivalent to double
that volume at half that pressure. Work is done by the former going to the
latter, or work is required to achieve the former from the latter.

Well, duh! What does that have to do with air not released from a
reservoir by a regulator?

Gary