In article ,
says...
On Tue, 6 Jan 2004 10:21:33 -0500, Ned Simmons wrote:
In article ,
says...


An air regulator valves *just enough* energy from the tank to
satisfy the load at any given moment. No more. The rest
*remains in the tank*.

Then please respond to my previous post and explain how
you're going to determine whether the water removed from a
reservoir, or the air released from a pressurized tank, was
used to do mechanical work, or simply released to the
environment. If you're correct it will be possible to tell
without looking beyond the boundaries of the reservoir or
tank.

If I'm correct, and I am, you have to *look* downstream to
see whether the water or air released was usefully employed.
There's no way to determine that from inside the tank.

So what you're saying is that you can release a pound of
air from a tank pressurized to 100psi and either:

A. Feed the air directly into a cylinder and do x ft*lbs of
mechanical work.

or

B. Run the released air thru a regulator set to 50 psi and
do a smaller amount of work.

If what you say is true, the difference in the amount of
mechanical work between the two cases will "remain in the
tank", but you can't detect that difference in energy
without looking outside the tank. You don't see the
contradiction here?


Fortunately, a regulator is a feedback device, it does "look"
downstream to see what the load demand is, and adjusts
itself to just supply that demand. In other words, it looks
at the downstream pressure and adjusts the flow just enough
to maintain the pressure at the set value. It lets no more air
through than is required to supply the energy the load
demands.


The regulator does not look downstream at the load demand,
it sees only the pressure at its outlet and adjusts the
flow to maintain this pressure. This in no way guarantees
optimal efficiency in the use of the energy available in
the air.

Ned Simmons