On Tue, 06 Jan 2004 04:04:40 -0600, Richard J Kinch
wrote:

Gary Coffman writes:

Now try it without the regulator. You can't do it as many times,
because energy stored in the tank has been *wasted* at each fill,
ie the pressure in the cylinder and tank equalize each time you
open the fill valve even though that's more energy than you *need*
to lift the weight one foot, and that excess energy is lost when you
vent the cylinder. This is a clear case where the *absence* of a
regulator wastes energy. It is in fact the *usual* case.

You are correct that with-the-regulator beats without-the-regulator, but
compressing-the-air-to-50-psi-to-start-with beats them both, which is to
say, if mechanical efficiency is the figure of merit, then a regulator on a
high-pressure supply is wasteful compared to an unregulated source at the
application pressure.

Yes, at the system level. It still has NOT been shown how any
energy remains in the regulator, or leaves it other than in the
downstream airflow, if the regulator doesn't get warmer. If energy
out = energy in, then there's no net loss at the regulator. We've
looked at other parts of the system and thought we accounted for the
energy and so inferred or deduced that there must be loss in the
regulator, but we've all failed to show how any energy leaves the
regulator other than in the gas going to the point of use.

Geez, my regulator is only 2 feet from me. Hope it ain't emitting
Xrays!