Locating underground conduit
Ed
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
David G. Nagel
Ed;
Run a metal snake into the conduit then get a metal detector and sweep
the area for the conduit. If this doesn't work there are wire tracing
detectors that might do the job. You hook the transmitter to the snake
and sweep with the detector.
If all fails you might try a metal probe. Stick the probe into the
ground and feel for the conduit. Or dig up a couple of feet of conduit.
Note the direction it is going then move in that direction and dig a
small trench where you thing the conduit is.
One of these methods should work.
If all fails install new conduit.
Dave WD9BDZ
Roy Lewallen
of pictures before the trench is filled. It's good to include distances
to some fixed reference points -- you can write them with a marker on
big pieces of paper laid on the ground to get them in the picture. I
haven't yet used the pictures I took of mine, but I sure have made a lot
of use of the pictures I took of the uncovered walls of a home addition,
showing the locations of all the studs and wiring.
Roy Lewallen, W7EL
AndyS
Couple a garden hose to the end you can find and run water into
the PVC.... Go to the area surrounding the buried end and look for
the
sandy ground to be wet......
Andy W4OAH
JB
"Ed" <Huckleber...@bigvalley.net> wrote in message
news:Xns9B37E2BFF7B46Hu...@198.186.192.196...
Stab an antenna rod down until you find it.
JIMMIE
Ive done this to locate wires in walls, might work for wires in
ground.
Make a buzzer form a relay by attaching the NC contacts in series with
the coil and battery.
Connect it to a wire running through the conduit making sure the wire
is not connected to power. The buzzer will generate enough hash you
can pick it up on a pocket AM rx.
Jimmie
Jeff Liebermann
wrote:
> 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.
If there is a wire in the conduit, just rent a "cable finder" from the
local rental yard. It's a low frequency transmitter and receiver
combination. If you have access to one end of the pipe, just shove a
metal "snake" into the pipe to provide a suitable conductor.
> The ground is nearly pure sand, and is well landscaped now to the
>point that I do not want to randomly dig it up.
That should be easy. Dry sand doesn't attenuate the signal much. Wet
sand is another story.
> The end terminated in an elbow curving up and is well duct taped
>shut.
Ummm... I think you'll find that the duct tape has dried out by now
and that your pipe is full of water and sand.
> Can anyone suggest a method or equipment I might use to locate that
>far end?
The cable finder is the right way. Ground penetrating radar will work
but is messy.
You can pressurize the conduit with an air compressor. That should
blow off what remains of the duct tape. Use your ears or a
stethescope to listen for the noise through the sand. If the end is
just below the surface, it should make a nice blow hole. Be prepared
to clean the sand out of your uncleable buried elbow.
If you think the pipe is clear, drop a small loudspeaker down the
other end and play rock music with a heavy bass beat. You should be
able hear that 50ft away. Use a stethescope.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Ed
_fEYEGjVnZ2d...@posted.easystreetonline:
Damn ! NOW you tell me ! :^)
actually, I did take a gazillion pictures of the house construction
and from foundation, through all framing, to completion... but I
neglected the outside !
Ed K7AAT
Ed
6fd68a...@s9g2000prm.googlegroups.com:
That's an excellent idea.... but I really hate water in my electrical
conduits.... I'll use that as a last resort. Thanks.
Ed
Ed
news:JdoJk.1244$r_3...@nwrddc02.gnilink.net:
A definate consideration.... since the ground is sand. If the
antenna rod doesn't just bend around the conduit... may just work. Tnx.
Ed
Ed
> Run a metal snake into the conduit then get a metal detector and sweep
> the area for the conduit. If this doesn't work there are wire tracing
> detectors that might do the job. You hook the transmitter to the snake
> and sweep with the detector.
> If all fails you might try a metal probe. Stick the probe into the
> ground and feel for the conduit. Or dig up a couple of feet of
> conduit. Note the direction it is going then move in that direction
> and dig a small trench where you thing the conduit is.
> One of these methods should work.
> If all fails install new conduit.
>
> Dave WD9BDZ
Dave, your idea above, plus some comments from others has made me
realize that this is the way I should proceed, for my first attempt. I
do have a Service Monitor. I'll simply run my snake into the empty pvc
conduit until it hits the end ( duct tape ) and connect an RF signal to
it, then using a small HT, track the signal down to the end.
My thanks to all for other ideas presented here, too.
Ed K7AAT
Jerry
Hi Ed
Have you considered the use of a wad of towel pulled thru the conduit to
dry it after using water to locate the burried end?
Compressed air could be used in place of the water. The air excaping
from the burried end shouild be easily detected.
Jerry KD6JDJ
Jim-NN7K
>> That's an excellent idea.... but I really hate water in my electrical
>> conduits.... I'll use that as a last resort. Thanks.
>>
>> Ed
>
When in doubt, couple ways the Pros do it:
1) Run a Metalic Snake thru it, and hook to a (Low Power RF , or a
Fairly high power A.F. source-- follow the snake (above ground with
an inductive sampler ( or rf receiver)) to the end - use a cable
marker (Paint) to follow the duct if needed to find an intermediate
point , then repeat agan if necessary.
2) for those that have access to a "THUMPER", can do the same
Apply high level of sound to the PVC, and use a listening device
to follow the noise, in the ground.
Works for locating buried cables for utilities- should work for you!
Jim NN7K
JERD
"Jim-NN7K" <nn7ke...@noway.net.> wrote in message
news:E5xJk.2678$W06....@flpi148.ffdc.sbc.com...
What an interesting thread!
How about one of those 'stage' smoke machines pumped into the open end?
VK5JE
Cable Shill
Another simple way - the old Native American waiting for a train
method. Push the fish tape all the way until it stops. Person 1 keeps
ramming the fish tape and person 2 puts ear to ground near far end and
listens for it. Needs no batteries or smoke.
Nix the water. I like the compressed air trick, Just don't look
directly at the conduit end . .
--
"From spongecake to satellites, it's gotta be Krebstar"
Ed
> Another simple way - the old Native American waiting for a train
> method. Push the fish tape all the way until it stops. Person 1 keeps
> ramming the fish tape and person 2 puts ear to ground near far end and
> listens for it. Needs no batteries or smoke.
>
I like that! I will try it before bothering to hook up an RF source to
the fish tape!
Ed K7AAT
Ed
>
> How about one of those 'stage' smoke machines pumped into the open
> end?
>
> VK5JE
That's a good one, too, but in my case, I KNOW that I duct taped the
end of the conduit in such a manner that it is truly air tight... even
possibly under pressure. Thanks anyway.
Ed
Jeff Liebermann
<cable...@comcast.net> wrote:
>Another simple way - the old Native American waiting for a train
>method. Push the fish tape all the way until it stops. Person 1 keeps
>ramming the fish tape and person 2 puts ear to ground near far end and
>listens for it. Needs no batteries or smoke.
>
>Nix the water. I like the compressed air trick, Just don't look
>directly at the conduit end . .
Well, how about combining the two methods? Find some flex lawn drip
irrigation tubing. Attach a bosons whistle to the end and shove it
through the pipe. Add compressed air and it should scream like a
banshee. That should be easy to hear through the sand. Maybe the
duct tape will act as a diaphragm.
David G. Nagel
Ed;
Thanks for the compliment. I wish you luck and envy you for your acreage
for antenna's. My lot here in St. Louis is something like 40 feet by
120 feet with the house in the center. I do have some trees along the
back alley that I have wire hanging from. Works but not optimal.
Let us know how everything works out.
Dave WD9BDZ
Denny
will auger up through that duct tape and sand like it is tissue
paper...
denny/ k8do
Jeff Liebermann
wrote:
Ummm.... this is through 3/4" schedule 40 PVC with at least two right
angles. The augers I've seen are for much larger sewer drain pipe and
will not fit inside 3/4" PVC. Anything that can drill through sand
can probably also do some real damage to the PVC. A much smaller
diameter "snake" is probably safer. With only 1ft of sand to push
through, a solid "tape" type electricians snake can be pushed through
by hand. The only down side is that the pipe will fill with sand when
the duct tape is breached, so cleanup may be a problem. If dry sand,
a small hose on the end of a vacuum cleaner should work.
Incidentally, the frequencies used by commerical cable finders are
815Hz, 8Khz, and 82KHz at 2-3 watts.
<http://www.rycominstruments.com/3-8879-Cable-Utility-Locator.asp>
However, that's good for 15 ft depth and many miles of cable. Higher
frequencies will probably work for 1ft of sand and only 100ft of wire.
JB
> angles. The augers I've seen are for much larger sewer drain pipe and
> will not fit inside 3/4" PVC. Anything that can drill through sand
Ouch! Unless you are trying to fish a phone line, you (might/might
not/want) WILL dig it all up and go to 2" with 45 degree bends and bevel the
inside edges. Once above ground you can break out to pull boxes.
You have my sympathy.
Jerry
Hi Ed
Will the taped end will not leak with 80 PSI air in the conduit?
Jerry KD6JDJ
Jeff Liebermann
Thanks for the sympathy but it's not my conduit or problem. The
plumbing belongs to Ed, K6AAT.
Question: What's the difference between conduit and plumbing?
Answer: Plumbing holds water. Otherwise, they're the same.
I'm not sure what might be going inside a 3/4" conduit, but if it's
for a tower, it's way too small. The original question does not
indicate what manner of wiring goes inside. With 3/4", you can get
perhaps one run of LMR400 plus some flat rotator cable and you're
full. Hard to tell from here.
It's also possible to place a diplexer (or triplexer) at both ends of
the single coax run for splitting out HF, VHF, and UHF. I've done
that when running multiple coax cables was impossible.
<http://www.rfparts.com/diamond/Product_Catalog/plexers.html>
It's been a long time since I've done any tower construction, but for
commercial installs, I never used buried coax runs. AC power for the
tower lights were in 3" steel threaded conduit (not EMT), but the coax
was all above ground. That shortened the coax runs about 25ft which
was well worth the effort.
Incidentally, a good trick is to *NOT* lay the conduit perfectly
horizontally plumb. Put one end lower than the other so that water
well drain into that end. Shove a PEX sprinkler line down to the low
point of pipe and pump out the water once a year. I prefer
pressurized conduit, but a water sump works fairly well.
I discovered, the hard way, why using steel pipe instead of PVC was a
good idea. With everything underground, the obvious parking location
for the crane, cherry picker, or propane truck was directly on top of
the buried PVC. After a few cracked pipes, I decided that steel was a
good idea.
I like to pressurize the conduit slightly to keep the water out. It's
really not necessary as most coax will survive when immersed. However,
everyone re-uses coax, which has cuts in the outer jacket, and which
might not be fully waterproof. A pressure gauge, bicycle valve,
bicycle pump, some putty, and a few PSI are good enough.
I almost forgot.... a slow death to the installer that shoved a coax
barrel splice down a stuffed conduit, thus insuring that all
subsequent coax runs will jam up against the coax connectors.
Also, this is what happens when a monopole tower is stuffed full of
coax cables, and some idiot decides to enlarge the hole with a cutting
torch.
<http://802.11junk.com/jeffl/pics/drivel/slides/monopoleBurn.html>
<http://odessaoffice.com/wireless/priceless.jpg>
Jeff Liebermann
wrote:
> Will the taped end will not leak with 80 PSI air in the conduit?
> Jerry KD6JDJ
Well, if it does leak, the sand above the duct tape will dribble down
into the 3/4" conduit creating a rather awkward clean up exercise.
That's why conduit runs usually terminate above the ground, not below.
The trick is to find the conduit end without blowing off the seal.
Jerry
"Jeff Liebermann" <je...@cruzio.com> wrote in message
news:bj6ff4dm3p95rob2q...@4ax.com...
Hi Jeff
It may be of little interest to the OP, but the sand might have difficulty
leaking back into a conduit with air blowing out of it. In addition, the
air might leak from a small rupture below the oipen end of the conduit.
The OP may have no access to compressed air anyway.
Jerry KD6JDJ
Jeff Liebermann
wrote:
>
>"Jeff Liebermann" <je...@cruzio.com> wrote in message
>news:bj6ff4dm3p95rob2q...@4ax.com...
>> On Thu, 16 Oct 2008 17:17:05 GMT, "Jerry" <jerry...@verizon.net>
>> wrote:
>>
>>> Will the taped end will not leak with 80 PSI air in the conduit?
>>> Jerry KD6JDJ
>>
>> Well, if it does leak, the sand above the duct tape will dribble down
>> into the 3/4" conduit creating a rather awkward clean up exercise.
>> That's why conduit runs usually terminate above the ground, not below.
>> The trick is to find the conduit end without blowing off the seal.
> Hi Jeff
> It may be of little interest to the OP, but the sand might have difficulty
>leaking back into a conduit with air blowing out of it. In addition, the
>air might leak from a small rupture below the oipen end of the conduit.
>The OP may have no access to compressed air anyway.
>
> Jerry KD6JDJ
Welcome to rec.radio.amateur.antenna.physics
Ok, let's do the math. Dry sand weighs 100 lb/cubic-foot. There's
about 1 ft of sand above the end of the 3/4" conduit. The weight
action is roughly conical, so the volume of sand involved is (my
guess) about:
100 lbs/ft^3 * 1/3 = 33 lbs of sand.
All that it acting on a 3/4" diameter pipe, with a cross sectional
area of about:
Pi * 0.75" = 2.4 in^2
Therefore, the pressure exerted by the sand is:
33 lbs / 2.4 in^2 = 14 PSI
So, if he can pressurize the pipe to more than 14 PSI, he can lift the
column of sand sufficiently to keep it from dribbling into the pipe.
Of course, it's not that simple. Laminar air flow, pressure gradients
across the conduit, and the effects of the duct tape will ruin my
simplistic guesswork. Worse, the back pressure created by the
immovable column of sand will force some sand particles into the
conduit around the edges with the "reflected" air pressure. In the
middle of the conduit, the air flow is all out of the conduit, but
near the edges, it could easily be the other direction. I'm also
assuming that the sand is a perfect air seal, which it's not. To
prevent all this from happening, the minimum air pressure should be
about twice the 14 PSI, which is easily achievable with an air
compressor, but not a vacuum cleaner.
I'm also trying to imagine how the process will work. I see an air
compressor pumping madly away as the neighbors kids furiously dig
around the resultant sand volcano, as sand rapidly refills the conical
hole. In my never humble opinion, there's no way to prevent sand from
dropping into the conduit if the duct tape seal is broken before
excavating the end of the conduit.
Once the sand is in the conduit, just blowing air through the pipe
isn't going to magically elevate the sand particles 1ft or more in the
air. The air does not have sufficient mass to convey enough momentum
to move the sand particles, much less eject them vertically. For
that, one needs a denser medium, such as water. Shoving a plunger
through might work, but it's equally likely to jam sand particles into
the PVC conduit walls.
Richard Clark
wrote:
> Worse, the back pressure created by the
>immovable column of sand will force some sand particles into the
>conduit around the edges with the "reflected" air pressure.
H E R E S Y
Reflected waves do NOT have power in them - or so goes the catechism.
This new and dangerous introduction of a side topic can only lead to
endless debate about the superposition phase properties of sand in
vacua (particel theories inhabiting the crevices in the science of
Equal Librium)
73's
Richard Clark, KB7QHC
Jerry
Wow, Jeff, you are a really smart guy. It sure is nice to know that you
are able to analyze this sand over conduit problem so thoroughly. Heck, I
thought the air would blow out thru the sand. I didnt even consider the
sand above the air leak to be immovable. I thought the air would find a
path to leak out somewhere between the tape and the conduit. I hadnt
thought about using neighbor kids. Why would you consider using kids for
this project?
I'll assume you wont recommend the OP use water or air to locate the far
end of his conduit.
Jerry KD6JDJ
Jeff Liebermann
wrote:
>On Thu, 16 Oct 2008 13:57:44 -0700, Jeff Liebermann <je...@cruzio.com>
>wrote:
>
>> Worse, the back pressure created by the
>>immovable column of sand will force some sand particles into the
>>conduit around the edges with the "reflected" air pressure.
>H E R E S Y
Hershey Bar (Chocolate Rules). Besides, following the orthodoxy lacks
entertainment value.
>Reflected waves do NOT have power in them - or so goes the catechism.
>
>This new and dangerous introduction of a side topic can only lead to
>endless debate about the superposition phase properties of sand in
>vacua (particel theories inhabiting the crevices in the science of
>Equal Librium)
Yeah, but I like playing in the sand. Try this experiment next time
you have an air compressor and nozzle handy. Find a cardboard,
plastic or metal tube at least 3 ft long. A vacuum cleaner extension
pipe will suffice. Plug up the other end with whatever is handy. Blow
air into the center of the tube. Run your fingers around the edges of
the tube and note which way the air is flowing. That's what will
happen if the compressed air is not sufficient to blow 30 lbs of sand
into the air. The air and the sand will flow back into the pipe in
the opposite direction as the compressed air.
>73's
>Richard Clark, KB7QHC
--
Jeff Liebermann
wrote:
> Wow, Jeff, you are a really smart guy. It sure is nice to know that you
>are able to analyze this sand over conduit problem so thoroughly.
Nope. My guesswork is far from exact. Close enough.
>Heck, I
>thought the air would blow out thru the sand. I didnt even consider the
>sand above the air leak to be immovable.
It is immovable, until it moves. That's the real problem. We can
consider the sand to be a solid plug until it starts to break up. As
soon as that happens, it leaks like a sieve. As soon as it starts
leaking, the air pressure available for lifting the sand is
dissipated, resulting in the collapse of the sand pile. Think of it
like a real volcano. As soon as the volcano stops erupting and
belching gasses, the eruption column of airborne rock collapses, heads
for the ground, and creates a messy pyroplastic flow.
>I thought the air would find a
>path to leak out somewhere between the tape and the conduit.
There's plenty of opportunities for air leaks. If the PVC joints
aren't glued, the air pressure will probably separate the lengths of
PVC pipe.
>I hadnt
>thought about using neighbor kids.
Anyone that uses 3/4" PVC for antenna conduit, and then buries and
loses one end, is certainly not a professional underground
construction contractor. He certainly isn't going to use high prices
professional union ditch diggers. The cheapest alternative are the
neighbors kids. I currently have a horde of them working on removing
the blackberries from my hillside. It may take months and result in a
few non-fatal injuries, but it's still cheaper than hiring a landscape
contractor. Also, more fun to watch.
>Why would you consider using kids for
>this project?
They work cheaply. They're familiar with playing in the sand using
shovels and pails. Just tell them it's kinda like at the beach. They
also bounce instead of break at a young age, which makes them suitable
for dangerous tasks.
>I'll assume you wont recommend the OP use water or air to locate the far
>end of his conduit.
I posted some serious recommendations in previous rants. I like
dropping a boson's whistle down the pipe at the end of a small
diameter air hose. Apply air pressure and it should be hear through a
foot of sand. If not, it will surely scare the gophers, which might
be useful.
> Jerry KD6JDJ
Richard Clark
wrote:
>Plug up the other end with whatever is handy. Blow
>air into the center of the tube. Run your fingers around the edges of
>the tube and note which way the air is flowing. That's what will
>happen if the compressed air is not sufficient to blow 30 lbs of sand
>into the air. The air and the sand will flow back into the pipe in
>the opposite direction as the compressed air.
Hi Jeff,
Well, it's been a coon's age since I've seen vacuum cleaners that
would let me attach to their exhaust - so that's out.
As for driving compressed air into a short (or open). I've done that,
but not for sand excavation. Rather, I've used what was commercially
called the "vortex effect" which separates the two air current flows
you allude to above to create a hot stream and a chilled stream of
air. (Elevated or depressed from the average of the inlet
temperature.) I used this for cooling electronics in a paper mill.
Not particularly efficient, but compressed air was available, and the
VorTec nozzle was a quick and easy solution to their NEMA enclosures.
See:
http://www.vortec.com/support_casestudies.php
or
https://secure.vortec.com/store_products.php?catID=9&prodID=6
This, and some of my fluidic applications constitute a specialized
niche in alternative logic systems. Notably, they all work off
principles of reflected power that demonstrate palpable examples.
ji...@specsol.spam.sux.com
> Well, it's been a coon's age since I've seen vacuum cleaners that
> would let me attach to their exhaust - so that's out.
Have you ever heard of a shop vacuum?
Usually only available at highly specialized stores such as Walmart.
--
Jim Pennino
Remove .spam.sux to reply.
Richard Clark
>Richard Clark <kb7...@comcast.net> wrote:
>
>> Well, it's been a coon's age since I've seen vacuum cleaners that
>> would let me attach to their exhaust - so that's out.
>
>Have you ever heard of a shop vacuum?
>
>Usually only available at highly specialized stores such as Walmart.
Hi Jim,
Unfortunately my shopping nature turns me more towards Fry's and I
certainly have very little interest in yet another vacuum cleaner (if
they offer them). Market forces long (decades) ago convinced me that
Hardware skills were in a declining employment segment in proportion
to software.
There may not be a software solution to this current problem of
locating a buried pipe, but I wouldn't have buried it without some
simple binary marker (it's here!). The analog solutions offered are
inventive, and I do appreciate them however. One or several are
probably far more effective than going to Walmart for a shop-vac (that
would only become a permanent altar attesting to my need to use it in
justification for its expense).
JIMMIE
> A suggestion for other folks who will be burying a conduit: Take a bunch
> of pictures before the trench is filled. It's good to include distances
> to some fixed reference points -- you can write them with a marker on
> big pieces of paper laid on the ground to get them in the picture. I
> haven't yet used the pictures I took of mine, but I sure have made a lot
> of use of the pictures I took of the uncovered walls of a home addition,
> showing the locations of all the studs and wiring.
>
> Roy Lewallen, W7EL
We always do this at work and lately started doing GPS surveys of new
buried cables marking GPS and survey data on the pictures, This comes
in real handy when you are paying for 4 guys and a rented backhoe to
stand around and wait for you to find a cable,
Jimmie
Jeff Liebermann
wrote:
>Well, it's been a coon's age since I've seen vacuum cleaners that
>would let me attach to their exhaust - so that's out.
The problem with vacuum cleaners is that they all suck. I have an
ancient Electrolux and a Shop Vac that both have usable exhaust ports.
I also have a Hoover upright and a Hoover cannister in the office that
do not. Y'er right that it's a vanishing breed.
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. 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.
>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.
>Rather, I've used what was commercially
>called the "vortex effect" which separates the two air current flows
>you allude to above to create a hot stream and a chilled stream of
>air. (Elevated or depressed from the average of the inlet
>temperature.) I used this for cooling electronics in a paper mill.
>Not particularly efficient, but compressed air was available, and the
>VorTec nozzle was a quick and easy solution to their NEMA enclosures.
>
>See:
>http://www.vortec.com/support_casestudies.php
>or
>https://secure.vortec.com/store_products.php?catID=9&prodID=6
Nice. I built several out of the original Amateur Scientist book
(which I still have on my bookshelf) in the early 1960's. It worked
amazingly well. Much later, I built one out of PVC pipe, which
melted. Now I know why they're made out of metal. Never mind the
inefficiency. It's the noise they make that drives me nuts. At one
point, we had 4 of them in series, with 4 assorted air compressors
pumping about 4 SCFM into each, and got it down to about -100C. We
started with a group of about 10 lab students, and ended up with a
crowd of about 100 nosey students wondering why someone was trying to
operate a jet engine on campus.
>This, and some of my fluidic applications constitute a specialized
>niche in alternative logic systems. Notably, they all work off
>principles of reflected power that demonstrate palpable examples.
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.
Richard Clark
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.
ji...@specsol.spam.sux.com
Everyone needs a shop vac, especially a wet and dry one.
Unless you really like spending a long time mopping floors.
Richard Clark
>Everyone needs a shop vac, especially a wet and dry one.
>
>Unless you really like spending a long time mopping floors.
I was once a swab jockey. Mind? when there was no choice you turn
that off.
Hi Jim,
I prefer dry floors. That's why I invested in a French drain. And I
have more floor space than that which would have been lost to a barrel
that sucks.
Jeff Liebermann
wrote:
>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.
Ouch. At that pressure, the first few drops of oil will give you an
instant tattoo. An acquaintance recently had that happen to him. He's
now recovering from the skin grafts and laser ablative cleanup.
The closest I came to that was getting a hydraulic fluid shower while
riding as an operator inside a Rose Float (in about 1968). The floats
animation was run by a pony engine and hydraulic pumps. The coupling
directly over me started to leak. After 2 hours in the float
lumbering through Pasadena, I arrived thoroughly soaked.
<http://802.11junk.com/jeffl/pics/jeffl/slides/RoseFloat01.html>
That's me testing the chair position (which was arc welded in place so
it had to be perfect). My feet are resting on top of the electrical
animation switching panel.
>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.
Well, I missed such fun when I was younger. I worked for the same
monopoly. While you were playing in the muck, I was "re-enforcing"
100 pair bundles and working in the battery room.
>Substituting one central phrase of "Apocalypse Now":
> "The aroma of it all! The AROMA of it all!"
These days, the installers doing FTTS (Fiber Through the Sewers) have
all the fun. Instead of summer interns, the dirty work is done by a
robot which installs a SAM (sewer access module):
<http://www.kate-pmo.ch/pages/en/fast.html>
Despite the robotics and improved handling, the packets delivered
still seem to smell of effluvia.
>... 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.
Chuckle. Very true. Worse, the "real" agendas of both parties are
almost identical. I noticed that both parties are also against the
status quo (which is generally considered awful). That makes me
wonder just what they are in favor of actually doing. I would prefer
they do absolutely nothing and let the economy fix itself, but that's
too much to hope for. Let the lesser evil win in Nov and never mind
trying to decode their logic.
I should feel guilty for encouraging this off topic discussion,
complete with topic drift, but I don't.
Richard Clark
wrote:
>I should feel guilty for encouraging this off topic discussion,
>complete with topic drift, but I don't.
Hi Jeff,
I count it as adding value - even if it is for political education,
sewer management (I didn't mean for that juxtaposition, but Karma
seeks its own balance), and the parade of roses systems control. That
photo was a blast. Did you actually have to cross your feet as part
of the control heuristics?
At the end of Stiglitz's discussion on the cost of the war ($3 to $5
Trillion at a minimum), someone asked plaintively "Don't you have
something positive to offer us?" He responded "We will have a new
president soon."
lt...@yahoo.com
detector to find the 'snake'. Ought'a be able to find a metal
detector some where...
- 'Doc
(Tape a bottle cap to the end of that 'snake', they're easy to find.)
Howard K0ACF
hook a toner to one end & with the reciever you will here it & find the
end....I have had to trace phone lines a few blocks long & underground also.
They do work....news:Xns9B37E2BFF7B46Hu...@198.186.192.196...
>
> 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
JB
Try stuffing your coax past the first 90 degree bend. If this won't work,
you KNOW you will have to tear it all out again and redo it.
Ed
My thanks to the entire group for the excellent responses (mostly :^)
) on my problem. It was only yesterday that I finally had opportunity
to address it.
The RF on the fish line did not work.... just did not seem to couple
and radiate. However, a very very simple procedure ( one of you
mentioned this ) did work. I had my wife pull and push the fish tape
back and forth while I listened very closely for any sound of it thumping
against the end of the pvc at the far end. It worked. I did not
actually hear it hittingi the duct tape, but I did hear it as it moved
back and forth on the last sweep at the end. It was only about 8 inches
under the surface of the sand ( much less than I had thought ) and was
located farily easily.
You guys came up with a plethora of solutions which would have been fun
to try.... one of the reasons I posted the question to this group,
even though a bit off topic.
To answer one question, the PVC will only be used for electrical, not
antenna, so the 3/4" is quite sufficient for my needs.
Again, thanks to all. I won't forget some of these methods suggested.
Ed K7AAT
Richard Harrison
"The RF on the fish line did not work."
Problem is that loss is proportional to signal frequency through the
earth, A low audio tone is much more appropriate. With a low audio tone
on an insulated conductor buried in the earth with reference to a ground
rod or ground bed, the conductor can be traced for miles. I`ve traced
4-ft. diameter poorly insulated steel pipelines for 8 miles or more and
they were buried several feet down for protection.
Reception can use a relay coil to sense the audio signal which is fed to
an audio amplifier and earphones. The coil core points toward the
conductor.
From the angles made by the core on both sides of the conductor the
depth of its cover can be closely estimated.
Best regards, Richard Harrison, KB5WZI
Richard Clark
Harrison) wrote:
>With a low audio tone
>on an insulated conductor buried in the earth with reference to a ground
>rod or ground bed, the conductor can be traced for miles.
During WWI, Heinrich Barkhausen was working with army field telephones
that exhibited strange whistling sounds, unrelated to the war
communications. These sounds were the RF emissions of lightning in
the AF band. What is more interesting is that the mode of propagation
was along Earth's magnetic flux lines, and the scale of propagation
was hemispheric.
As a byproduct of this research, Barkhausen suggested subterranean
communication employing a widely separated pair of rods in the earth,
and driving them with audio frequency communications. Range was
reportedly a function of the distance between the rods. The receiver
used the same earth connection method.
This was the subject of a Popular Electronics article in the mid 60s.
Not reported in that journal, Beverage of antenna fame was working at
the same time trying to develop a reliable RF communication system for
sending orders to troops in the field in Europe, from the US. His
system was a ground level wire of several 10s of miles long, oriented
end-on towards Europe. Troops could hear the US broadcasts in the
field with unsophisticated equipment. However, transmissions back to
the US didn't fare as well. They were overwhelmed on receive by the
back side orientation of the long wire towards the Caribbean and its
summer electrical storms. Dr. Beverage solved that by extending the
wire in that direction too and with termination.
Those frequencies were easily 30 times, or more, higher than
Barkhausen's suggestion - hence the very looooooong wire.
Richard Harrison
"These sounds were the RF emissions of lightning in the AF band."
Richard also noted whistling sounds in army field telephones. I`ve seen
these audio radiations called "whistlers".
My efforts were to locate buried pipelines by a more convenient method
than bouncing a metal pick off of them. Pipeline rights of way can be
wide and pipes are often not where one may think but may be at odd
distances from the center of the right of way.
Connecting a signal to the pipe is much more effective than bouncing
signals off the pipe or detuning a metal locator with the pipe. Another
pipe tracing method in use is a vehicle (pig) launched into the pipe.
The pig contains a pneumatic hammer which produces so much noise that
it is easily heard through all the ground covering the pipe. Effective,
but it is not cheap to launch and recover pigs.
I`ve found broken pipes at the bottom of the Brazos River in Texas and
around offshore platforms in the Gulf of Mexico.
My efforts began with the availability of cheap SCR`s. I placed them to
key the output of cathodic protection rectifiers at a low audio
frequency rate. It worked well.
For more portability, I constructed a complimentary symmetry bipolar
power transistor generator which incorporated a 400-cycle Variac. The
generator was adjusted to produce a 12-Hz switching rate which proved to
work well. Output of the Variac was adjusted to give maximum power tnto
the pipeline wherever it was used from the switched 12 V automobile
battery. Connections to the pipeline are readily available at the
cathodic protection test points at intervals of several miles all along
the pipe.
Richard Harrison
"---calibrating a pressure gauge to 10,000 PSI when the coupling line
split sending a fine spray of pressurized oil past my face."
I had a similar experience but at about 1/10 the pressure. It was
exciting nonetheless.
I was on watch in the engine room of an LSM in the middle of the Pacific
during WW-2 and we were cruising at our usual 10 or 12 knots but alone,
that is not in a convoy.
We were equipped with (2) 1800 HP 10-cyl opposed piston Fairbanks Morse
engines. To reverse an engine it is stopped then restarted with reversed
rotation. This is accomplished by shifting the position of the camshaft
within the engine with the engine controller. There is an automatically
operated electric engine brake which clamps the engine shaft to stop its
rotation during its rotation change. It has an enormous solenoid which
holds the brake off while the engine is running but this can be defeated
with a mechanical stop and a switch to save solenoid power if direction
changes are unlikely. That`s how we were running to conserve power
unescorted at sea.
Suddenly the annunciator in front of me jinggled and ordered "Full Speed
Astern". Without switching shaft brake power back on I complied.
Suddenly the engine room was full of diesel oil mist, water mist, and
smoke. I couldn`t imagine what had happened, but the engine started
fine, thank you. in the reverse direction but I couldn`t see my hand in
front of my face. After awhile, it dawned on me what had happened.
Compresson pressure had fedback into the air compressor system blowing
its pressure relief valve and filling the engine room with water from
the compressor tank and diesel fuel from the engine cylinders. It was a
mess but the exhaust air curculation soon cleared the atmosphere and no
harm was done. Never again did I forget to enable the shaft brake before
reversing engine directions. I was promoted to MoMM 3rd class and put in
charge of my watch. My battle station was gun loader on the 40mm
anti-aircraft guns.
Ed
>
> Problem is that loss is proportional to signal frequency through the
> earth, A low audio tone is much more appropriate. With a low audio tone
> on an insulated conductor buried in the earth with reference to a ground
> rod or ground bed, the conductor can be traced for miles. I`ve traced
> 4-ft. diameter poorly insulated steel pipelines for 8 miles or more and
> they were buried several feet down for protection.
Thats a suggestion that I would have liked to have tried. I have the
generator, and could have easily fabricated a "receiver". Oh well.
Another technique to add to the repertoire !
Ed K7AAT
Jeff Liebermann
wrote:
>...and the parade of roses systems control. That
>photo was a blast. Did you actually have to cross your feet as part
>of the control heuristics?
I'm slightly bow legged so crossing my feet is a more natural resting
position. The resting position was very important at the start of the
Rose Parade. The floats, horses, cars, etc all start getting
organized at about 4AM. The parade starts at 8AM. The floats are
never totally completed by New Year's day, so frantic last minute work
at the starting point was normal. At this point, none of those
involved have had more than one or two hours sleep, so a functional
sleeping position is a basic requirement. I installed padding on top
of the control panel for my feet.
I think I only managed to get about 30 minutes of sleep before the
unexpected happened. In 1968, we were behind an equestrian unit.
After standing in essentially the same spot for about 3 hours, the
horses deposited quite a pile of droppings on the pavement. There was
a false start somewhat before 8AM. All the floats and horses lurched
forward a few feet, placing our float directly over the pile. Besides
the smell, the real worry was what would happen if the leaky hydraulic
coupling mixed hot hydraulic fluid with horse dung. I was ready with
a large fire extinguisher. Fortunately, nothing happened but we all
nearly vomited from the stench.
If you look a the photo:
<http://802.11junk.com/jeffl/pics/jeffl/slides/RoseFloat01.html>
you'll notice a large hinge point directly above my sleeping form.
Part of the animation was a young boy, sleeping in bed, who raises up
and scratches his eyes, when he sees the toys at the foot of the bed
come alive. The kid was huge, thus the giant hinge. It worked fairly
well throughout the parade. However, when drove the float back to
Pomona for disassembly, it was discovered that all the 5/8"(???) bolts
holding the boy to the hinge frame had halfway sheared through.
This is the current animation system:
<http://cpprosefloat.org/site/page.php?23>
In 1968, it was several partly insane students, flipping switches and
toggling valves by hand. Cal Poly tended to win the animation prizes.
To bring things back to ham radio antennas, we had a Motorola
Breakie-Backie "portable" radio in the float on 2 meters. Tubes,
vibrators, wet cells, and muscle. It sorta worked, but the chicken
wire covering the float made a very effective shield. The antenna
ended up hanging under the float as we didn't want it visible on top.
Someone saw the "loose wire" and clipped it off just before the start
of the parade. I made a replacement out of some baling wire. It
worked, but about half way through the parade, the vibrator power
supply quit. Oh well.
Jim Lux
> On Fri, 17 Oct 2008 11:11:13 -0700, Richard Clark <kb7...@comcast.net>
> wrote:
>
>> ...and the parade of roses systems control. That
>> photo was a blast. Did you actually have to cross your feet as part
>> of the control heuristics?
>
> To bring things back to ham radio antennas, we had a Motorola
> Breakie-Backie "portable" radio in the float on 2 meters.
It's a challenge to put antennas on floats and meet the TORC
requirements for only vegetable matter to be exposed. We got a special
dispensation for our 23cm ATV from the JPL float.
Jeff Liebermann
wrote:
>Jeff Liebermann wrote:
>> To bring things back to ham radio antennas, we had a Motorola
>> Breakie-Backie "portable" radio in the float on 2 meters.
>It's a challenge to put antennas on floats and meet the TORC
>requirements for only vegetable matter to be exposed. We got a special
>dispensation for our 23cm ATV from the JPL float.
>
>http://www.luxfamily.com/events/rose2005/roseatv.htm
Things sure have changed in 40 years.
Nicely done float. How tall is it? We had stability problems with
some of the floats. The parade route was fine, but entering Victory
Park at the end was tricky. One year, some of the floats almost
tipped over.
Also, my fault tolerant memory has failed me once again. The snoozing
photo of me is from of the 1970 float:
<http://cpprosefloat.org/site/plugins/autogallery/autogallery.php?show=7.Past%20Floats%2F350.1970.jpg>
The float consisted of 3 islands, connected with big long throw
hydraulic rams. The float could be contracted to about 35 ft or
extended to 59.99999 ft. The fun part was turning the Orange Grove to
Colorado corner in front of the cameras, while simultaneously
extending the float. Some officials didn't know which way the float
was going to go and ran for cover.
The sheared hinge bolts were from the 1971 float:
<http://cpprosefloat.org/site/plugins/autogallery/autogallery.php?show=7.Past%20Floats%2F340.1971.jpg>
It also features an elephant toy, with targeting controls for a small
water pump and nozzle in the trunk. That was banned the following
year.
--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 je...@comix.santa-cruz.ca.us
# http://802.11junk.com je...@cruzio.com
# http://www.LearnByDestroying.com AE6KS
JosephKK
wrote:
>On Tue, 21 Oct 2008 13:22:33 -0700, Jim Lux <james...@jpl.nasa.gov>
70 & 71? Maybe you met Dave Steinfeld of TORRA . I worked with him
for some years back in the day (80's).
Jeff Liebermann
wrote:
>70 & 71? Maybe you met Dave Steinfeld of TORRA . I worked with him
>for some years back in the day (80's).
Nope. I don't recall the name. I only associated with radicals,
leftists, protesters, anarchists, dissidents, draft dodgers, and a few
engineers. If he was anything resembling a normal student, I probably
didn't meet him. Also, I don't think that TORRA existed in 1971 and
before:
<http://www.torra.us/id4.html>
There were very few active hams involved in construction of the floats
at Cal Poly Pomona. I think there were only 2 or 3 electrical
engineering students involved. At the time, the design and
construction was dominated by Agricultural Business Mgmt students. It
was easy to tell the difference. Engineers wore cowboy boots and ABM
students wore suits, string ties, and carried brief a case.
Jim Lux
> On Tue, 21 Oct 2008 15:38:46 -0700, Jeff Liebermann <je...@cruzio.com>
> wrote:
>
>> On Tue, 21 Oct 2008 13:22:33 -0700, Jim Lux <james...@jpl.nasa.gov>
>> wrote:
>>
>>> Jeff Liebermann wrote:
>>>> To bring things back to ham radio antennas, we had a Motorola
>>>> Breakie-Backie "portable" radio in the float on 2 meters.
>>> It's a challenge to put antennas on floats and meet the TORC
>>> requirements for only vegetable matter to be exposed. We got a special
>>> dispensation for our 23cm ATV from the JPL float.
>>>
>>> http://www.luxfamily.com/events/rose2005/roseatv.htm
>> Things sure have changed in 40 years.
>>
>> Nicely done float. How tall is it? We had stability problems with
>> some of the floats. The parade route was fine, but entering Victory
>> Park at the end was tricky. One year, some of the floats almost
>> tipped over.
Don't recall how tall it was, but it laid back down to get under the
overpass at the end of the route. It was built by professional float
builders (Phoenix)
http://floatcam.caltech.edu/ has a link to video clips during
construction, etc.
>
> 70 & 71? Maybe you met Dave Steinfeld of TORRA . I worked with him
> for some years back in the day (80's).
Would that be WA6ZVE? He works in the RF Cal lab here at JPL.
>
Jeff Liebermann
wrote:
>Don't recall how tall it was, but it laid back down to get under the
>overpass at the end of the route. It was built by professional float
>builders (Phoenix)
>http://floatcam.caltech.edu/ has a link to video clips during
>construction, etc.
My Real Media player is having its usual bad day. I'll look at it
later.
I forgot about the overpass. That would be a problem. One year,
someone built a float over a large fork lift. The plan was to lower
it at the overpass and again at the park entrance (due to overhanging
wires). When the forks were lowered, the skin of the float was
shredded. Someone used baling wire to tie together the ends of the
chicken wire skin at the junction. Oops.
Cal Poly traded space in the Rose Palace with D.E. Bent and Sons. I
think he retired in about 1978. We supplied him with surplus labor
(mostly for decorating and handling flowers) in trade for floor space
and "borrowing" tools. It was a very professional operation.
One of the funniest things was watching Disney Animation attempt to
build their first animated float. Everyone expected big things from
them due to their experience at Disneyland. As expected, the float
had more moving parts than stationary. Just one problem; Disney ran
on pneumatics instead of hydraulics.
The centerpiece of their design was a rather large globe with a
satellite spinning around it. The globe was bisected at the equator
with a cantilever rod supporting the satellite. It, and other moving
parts, sorta worked. Then, they added the flowers and watered them.
That added lots of weight, which they hadn't expected. The support
rod bent and had to be reinforced. Instead of smoothly orbiting the
planet, the satellite lurched and jerked its way around the globe. The
pneumatics could not overcome the added friction. The pressure just
built up and up until the satellite suddenly lurched free. This was
repeated every minute or so. I vaguely recall that it finally died
about half way through the parade when some hose or fitting finally
broke from the concussions. By then, all the flowers had been
catapulted off anyway.
JIMMIE
> 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
Jerry
"JIMMIE" <JIMMIE...@yahoo.com> wrote in message
news:9ccf907f-043f-44c1...@k13g2000hse.googlegroups.com...
Jimmie
Hi Jimmie
That "air" idea wont work, Jeff told me so
Quote Jeff --
"Welcome to rec.radio.amateur.antenna.physics
Ok, let's do the math. Dry sand weighs 100 lb/cubic-foot. There's
about 1 ft of sand above the end of the 3/4" conduit. The weight
action is roughly conical, so the volume of sand involved is (my
guess) about:
100 lbs/ft^3 * 1/3 = 33 lbs of sand.
All that it acting on a 3/4" diameter pipe, with a cross sectional
area of about:
Pi * 0.75" = 2.4 in^2
Therefore, the pressure exerted by the sand is:
33 lbs / 2.4 in^2 = 14 PSI
So, if he can pressurize the pipe to more than 14 PSI, he can lift the
column of sand sufficiently to keep it from dribbling into the pipe.
Of course, it's not that simple. Laminar air flow, pressure gradients
across the conduit, and the effects of the duct tape will ruin my
simplistic guesswork. Worse, the back pressure created by the
immovable column of sand will force some sand particles into the
conduit around the edges with the "reflected" air pressure. In the
middle of the conduit, the air flow is all out of the conduit, but
near the edges, it could easily be the other direction. I'm also
assuming that the sand is a perfect air seal, which it's not. To
prevent all this from happening, the minimum air pressure should be
about twice the 14 PSI, which is easily achievable with an air
compressor, but not a vacuum cleaner.
I'm also trying to imagine how the process will work. I see an air
compressor pumping madly away as the neighbors kids furiously dig
around the resultant sand volcano, as sand rapidly refills the conical
hole. In my never humble opinion, there's no way to prevent sand from
dropping into the conduit if the duct tape seal is broken before
excavating the end of the conduit.
Once the sand is in the conduit, just blowing air through the pipe
isn't going to magically elevate the sand particles 1ft or more in the
air. The air does not have sufficient mass to convey enough momentum
to move the sand particles, much less eject them vertically. For
that, one needs a denser medium, such as water. Shoving a plunger
through might work, but it's equally likely to jam sand particles into
the PVC conduit walls.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558"
Jerry KD6JDJ
Michael Coslo
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.
- 73 de Mike N3LI -
Ed
> 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.
>
Yes, making noise was key in locating my underground PVC. In my case,
I was able to locate the end by listening closely NEAR where I thought it
should have been while someone else was running a snake fully inserted in
the pvc back and forth a few inches.... the noise it made at the last
sweep was evident with no other background noise to interfere with it.
Ed K7AAT
Michael Coslo
And if Jimmie will let us borrow his dog, we'll be all set!
Denny
and I had to identify a coax that passed under the driveway... Ye old
wire tracer and 30 seconds is all it took to find it...
denny - k8do
JIMMIE
> "JIMMIE" <JIMMIEDEE...@yahoo.com> wrote in message
> Skype: JeffLiebermann AE6KS 831-336-2558"
>
> Jerry KD6JDJ- Hide quoted text -
>
> - Show quoted text -
Obviously you're an engineer. LOL
Jimmie
D. Stussy
news:gdpsil$1j3o$1...@f04n12.cac.psu.edu...
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.
Jerry
"D. Stussy" <sp...@bde-arc.ampr.org> wrote in message
news:gdqtub$5j6$1...@snarked.org...
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.
Jerry
>
>
JIMMIE
> "D. Stussy" <s...@bde-arc.ampr.org> wrote in message
>
> news:gdqtub$5j6$1...@snarked.org...
>
>
>
>
>
> > "Michael Coslo" <m...@psu.edu> wrote in message
> >news:gdpsil$1j3o$1...@f04n12.cac.psu.edu...
> >> Jerry wrote:
> >> > "JIMMIE" <JIMMIEDEE...@yahoo.com> wrote in message
>
>
> - Show quoted text -
I must admit that sand could get into the pipe but I cant see that
would be all that bad. My pipe had water in it that is really why I
was able to find it. If i want to clean it out I would just blow some
strips of cloth through it or in the case of sand rinse it out with
water then dry it out with warm air. Shop vacs are great for this. I
should have left the damned thing alone. Now my wife wants me to
finish putting in the spigot. She gave me a Thanksgiving suspense
date.
Jimmie
JB
case,
> I was able to locate the end by listening closely NEAR where I thought it
> should have been while someone else was running a snake fully inserted in
> the pvc back and forth a few inches.... the noise it made at the last
> sweep was evident with no other background noise to interfere with it.
>
> Ed K7AAT
Congrats!
That's probably the best answer, as you are going to fish something or not
and it's always more expedient to use the most handy tool first before
hauling out the hardware store or the drawing board. This is how it usually
plays out, that there is plenty of noise when you are trying to bang the
fishtape past the 90's. This is how I learned to use 45 degree sweeps and
pull boxes at every opportunity. Anything to avoid the frustration of
breaking wire or fish tape and wasting my own time.
D. Stussy
news:eo7Mk.3218$Rx2...@nwrddc01.gnilink.net...
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.
Ed
>
> 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.
For the record, I duct taped the end well, when it was initially
buried, in order to keep out sand and even water. It was applied well
enough to prevent any reasonable air pressure from moving it, in my
opinion. Duct Tape is awful sturdy stuff, and sticks quite well, too.
As I already said earlier, a bunch of you guys posted some excellent
ideas I could have used.... and I probably would have if my first simple
try with making noise with my fish tape hadn't worked.
Thanks again to all.
Ed K7AAT
Mike Coslo
That duct tape isn't at all likely to seal the pipe; some air will
escape - One of the reason's we don't repair flat tires with duct tape.
8^)
As an example of sound traveling underground, here in the
battleground state of PA, there are a lot of places where there are
streams underground. A tiny trickle of water can be heard even by my bad
ears, several feet underground.
Ed
>
> As an example of sound traveling underground, here in the
> battleground state of PA, there are a lot of places where there are
> streams underground. A tiny trickle of water can be heard even by my
> bad ears, several feet underground.
One little thing in my situation, we're about 1/3 mile away from the
Pacific North West Ocean surf and believe me, it is genearlly quite
loud.... enough to preclude hearing delicate sounds in the soil at times.
It took a relatively quiet day just to hear the fish tape rattling.
Ed :^)
JosephKK
wrote:
That call sign sounds right. The home / station address matches the
lookup to my address book. That is a good enough match for me.