I think some sort of acoustic (ultrasonic) technique has the best chance of
working.

I'd set up a 'pinger' at the bearing end.

At the other end I'd set up _two_ receivers.

I'd use a display that shows the relative time that the 'ping' gets to the
receivers.

Now you touch the two receiver probes to the mess of pipes at the valve/tank
end. You can tell which probe is closer to the 'pinger'. Now it is just a
version of the children's game hot/cold to find the incoming pipe (it will
be the only one where a probe 2' from the valve bank gets the signal before
a probe 1' from the valve bank does.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

----- Original Message -----
From: Bob Bullock <bobb@PROSTYLE.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, January 15, 2001 2:04 AM
Subject: [EE]: A tough design challange - how to trace metal pipes


> Hello all,
>
> A friend of mine's father has a company that installs and maintains
systems
> for delivering lubricating oil to large roller equipment such as in a
paper
> mill.  There can be hundreds of 1-1/4 inch metal pipes running out to
> bearings to deliver lubricating oil under pressure.  These pipes are
> sourced from a large bank of valves that are used to set the flow
> rates.  Many of these sites are several years old and what ever method
> (usually tags) that was used to mark the pipes as to where each one runs
> too, has long since disappeared.  He as asked me to build him something
> that can be used to trace the pipes.  When they do some sort of
> upgrade/maintenance they need to trace all of the pipes to the end
> bearings.  Currently, it can take a team of two people weeks to do this.
>
> The ideal method would involve attaching some form of signal generator to
> the pipe of interest, at the bearing end, and to use some form of detector
> at the end where all of the pipes meet and detect which pipe is the run
> that goes to the bearing with the generator on it.
>
> Some key limitations.  The pipes can not be brought out of use so there is
> no way to introduce anything into the pipe, or to insert anything internal
> to the pipe, it must all be done from the outside.  At several points near
> the end where all of the pipes meet, there are pipe clamps that
> electrically connect/short all of the pipes together.
>
> The pipes all end up connected to a common metal block.
>
> My thoughts have been along the line of possibly using sound.  If an
> ultrasonic signal was somehow injected into the pipe, maybe it could be
> detected at the other end.  Some energy would get reflected back into the
> adjacent pipes but should be at an attenuated level than the source
> pipe.  Also, if you were sending pulses,  there would be a phase change
> from the incident wave and the reflected waves. The pipes with reflected
> waves would all tend to be the same with the pipe with the incident wave
> standing out.
>
> Maybe these concepts would work with microwave signals as well.
>
> Anyway, its a stumper to me, but I have always been amazed at the creative
> ways to apply electrons devised on this list.  Naturally, I would want to
> use a PIC somewhere in it.
>
> Bob Bullock
> President
> Western Support Group Ltd.
> bobb@prostyle.com
> Certified Microchip Consultants
> http://www.microchip.com/10/Consult/Country/Canada/index6.htm#915-277
>
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>

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