On Sat, 3 Jan 2004 00:20:35 -0500, Ned Simmons
wrote:

I just did the same in Mathcad and am getting the same
results. (But shouldn't your units be inch-pounds?)

Oops! Yes, inch-pounds.

Would you mind emailing me your Mathcad file so I can
compare to what I'm doing? I'm using Mathcad 2000.

OK. I'll try to document it so it's clear what folly I've wrought in
the form of equations. :)


But the question that got this all started was whether a
regulator is analogous to a transformer and whether it's
possible to equate voltage and current to pressure and flow
in a compressible medium.

That was the question. I think it's clear that they are not
analogous. One must keep track of all of the energy, not just
pressure and flowrate. That was the flaw in my treating power as
pressure * flowrate. Power must be treated as rate of flow of total
energy.

The fact that a regulator doesn't get noticably warm indicates to me
that power (and energy) is not being lost there, but I'm still not
clear on how that can be. My best guess at the moment is that some
potential energy is converted from pressure to heat but that the heat
is swept away in the downstream gas so the energy is preserved in the
downstream gas.

It might be interesting to put a thermocouple on a regulator, wrap the
lot in thermal insulation, run it for a while and see what happens.

Note that I'm still avoiding discussions of thermo g.

Roger that!

Ned Simmons