On Fri, 17 Oct 2008 06:02:04 -0700, Jeff Liebermann
wrote:

However, you re-read what I scribbled, you might notice that I
suggested that one use the air compressor to pressurize the 3/4" PVC
pipe.

Hi Jeff,

I was responding to the broad assortment of methods which included
what was the closest option for me of a vacuum cleaner.

That's because the average vacuum cleaner can barely generate
more than a few PSI. They also leak badly. If you're trying to lift
a column of sand or demonstrate backpressure, it's much easier with a
proper air compressor.

No doubt and no argument. At one point in my career, I found myself
with a dead weight tester, calibrating a pressure gauge to 10,000 PSI
when the coupling line spit sending a fine spray of pressurized oil
past my face. Took me half an hour to shake off the thought of it
hitting me square.

As for driving compressed air into a short (or open). I've done that,
but not for sand excavation.

I have. The clumsy backhoe operator (me) once dropped a load of dirt
on top of the steel 3" conduit end during construction. I'm also the
idiot that forgot to shove a protective rag into the conduit end. I
spent the next two days trying to figure out how to get the dirt out
of the pipe. I eventually fabricated a cylinder shaped rubber plug
with an eyebolt down the center, dumped some water into the conduit,
and dragged the plug through the pipe with a winch. It took about 5
passes for the water to come out clear. I then pumped out the
remaining water, dragged a sponge through the pipe a few dozen times,
and then let evaporation do the final cleanup. Compressed air was
attempted just for fun, but it was obvious that it wasn't going to
lift the dirt out of the pipe.

I've done that too. For a summer of my youth (when dinosaurs ruled
the earth) I would plunge down a manhole with a tethered ball. I'd
plug it into the downhill side, clamber out, and fill the manhole with
water. Then go to the next manhole, clamber down and dig out all the
muck that had been plunged ahead of the tether ball. Repeat for
weeks.

Substituting one central phrase of "Apocalypse Now":
"The aroma of it all! The AROMA of it all!"

I'll pass. I don't believe in logic any more. Everything can be
explained in terms of politics, psychology, and conspriacies. Logic
is obsolete.

Last night I went to a reception for Joseph Stiglitz where he
mentioned being a liberal too much (he was apologizing to the group at
that point) and I drew him aside to comment that he had no need to
explain his bias as this was the first time in our political history
when we had two candidates BOTH running against the administration AND
the Republican Party. We laughed at that logic.

73's
Richard Clark, KB7QHC