"Jerry" wrote in message
...
"D. Stussy" wrote in message
...
"Michael Coslo" wrote in message
...
Jerry wrote:
"JIMMIE" wrote in message


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On Oct 15, 1:17 am, Ed wrote:
I know this is slightly off topic, but since I am intending to run
some RF cable in the conduit, and since there are a lot of
intelligent
hams on this group, I will proceed anyway:

Last year at the beginning of construction of a new house I buried
about 50 feet of 3/4" Sched. 40 PVD between the house and a location
on
the property perimeter. Now that I am ready to use it, I can not
locate the perimeter end.... it is somewhere in about a 10' area,
and
the
end curves up to probably about a foot underground.

The ground is nearly pure sand, and is well landscaped now to the
point that I do not want to randomly dig it up.

The end terminated in an elbow curving up and is well duct taped
shut.

Can anyone suggest a method or equipment I might use to locate that
far end?

Tnx.

Ed K7AAT

I have some pipe that I had run for an outdoor spigot that I never
finished installing. To test a method of finding it I shot some air
into it the other end was pretty easy to find by listening. I could
hear the rush of air and a lot of gurgling. My dog actually found it
in the roses bushes before I did.

Jimmie

Hi Jimmie

That "air" idea wont work, Jeff told me so

Quote Jeff --

"Welcome to rec.radio.amateur.antenna.physics

It can work, because what you are trying to do is not to move a lot
of air and sand, but try to make some noise. And you don't have to move
a whole lot of sand to do that. As long as the pipes stay together,
some
air will make it out of the open end and make some noise.

And where is the air going to escape? He said he duct-taped the end
shut.
With enough pressure, he'll have a blow-out, but that could also result
in
getting dirt inside the pipe, which I believe wouldn't be good.
However,
short of that, there's no hole for the air make noise....

He knows the length and direction. He should be able to make an
educated
guess as where to dig.

Hi D

You and Jeff may know something I didnt realize about sealing. I cant
imagine being able to make duct tape seal off the open end of a PVC pipe
with tuct tape, How much pressure can be sealed with the tape on the
side
of the PVC? I would have expected the tape to have been applied to
prevent
sand from entering. That wouldnt seal against much air pressure.
Furthermore, it is very easy to apply only adequate pressure to initiate
some air flow , not a sudden blast at high pressure to cause a crater. As
you know, a small amount of air flowing thru a small passage can produce
plenty of sound.
You are right, he has found the end of the pipe. I am curious to know
why it is necessary to write that the air leak method *wont* work when I
am
sure it will work, Jimmy has demonstrated that.

Well, let's see:

3/4" pipe, and duct tape is usually 2" wide. That means the entire end will
be covered with a single piece with its sides folded down. Duct tape is
designed NOT to let air pass. That means there's a good chance that the
seal was air-tight.