In article ,
says...
If I might take a moment to dither about the semantics
here.

"lowering the potential to do mechanical work" is
a bit different in some sense, than "loss." Because
of the history of electrical analogy here, this may
be confusing.

Yeah, "loss" is not strictly appropriate, but I don't think
it has caused too much confusion in the context of this
thread, and there's been worse use of terminology. In
particular, "potential energy" has been much misused.


Most folks think of the term 'loss' as a point loss,
ie a lumped circuit element that is dissipative. The
regulator, or the connection between the two tanks
in the case of no regulator, or even the expansion
orifice in the case where gas is expanding into
vacuum, are not analogous to electrical lumped circuit
elements like resistors. No heat appears in them
during the process. [1]

I've heard the term "lumped", but don't have even a vague
notion of what it means. I assume it's a simple concept?


(electrical analog discussion really are
doomed to fail here...)

Sure the end result having two tanks with three times
the volume, filled at a lower pressure, has less stored
potential. But the difference does not appear in the
regulator. The energy was not lost in the regulator.

A hydraulic regulator is functionally the same as a
pneumatic regulator, but it does get hot in operation.
Would you say that energy was lost in the regulator in that
case? (Again with the sloppy language.)

Ned Simmons