Gary Coffman wrote:
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

I thought this was about the air released, not the air that stays in the
reservoir. When this thread started some maintained that double the volume
at half the pressure could do the same work. I think a lot of the rest of
the argument resulted from the informal nature of the discussion. With a
blackboard, some sketches and math I think there would be more agreement
than disagreement.