Aboutcleggsan Expertise All technical areas of Electronics Engineering.
Experience BSEE, MBA, Design, R&D, University Research.
Senior Life Member of IEEE. Life Fellow of AES.
Organizations IEEE, Consumer Electronics Society, Audio Engineering Society.
Broad teaching experience; work experience mostly in consumer electronics and conversion from analog to digital technologies. Pioneer in digital audio at all levels.
Question I have a unique problem that I am at a loss to resolve. I have a couple of
ideas but am unsure if the one I am toying with now will be successful.
Maybe you can direct me on how to proceed.
We have built a 50 x 100 foot building and have incorporated about 6000
feet of 1/2 inch ID plastic tubing in the concrete floor to heat the building by
circulating hot water through it. The tubing is buried to a depth of 2 to 4
inches in the concrete. The tubing is spaced at 12 inches and tie wrapped to
a reinforcing steel grid. We now need to drill holes in the floor to secure the
base plates for some car lifting hoists. The holes will be every bit of 4 to 6
inches deep. We had taken photographs and did some primitive sketchings
of the tubing locations and paths and that will be of some help. However,
before we start to drill we want to make every effort at identifying the
locations of the tubing paths to the best of our ability.
Since the tubing is PVC and the concrete floor is full of reinforcing steel a
metal detector will be of no use. One idea we had was to circulate hot water
through a tubing loop (there are dozens of tubing loops of lengths from 200
to 300 feet) and then using an infrared viewer to see if we could identify the
tubing path. We think that with the tubing buried so deep that the heat
pattern at the surface will not be definitive enough. Spraying water on the
surface area and waiting for evaporation to reveal the pattern would probably
also not be definitive enough.
One idea that we believe has some merit in pursuing would be to insert a wire
into the tubing and attaching a signal generator to it. Then, using a
frequency detector we could probably get very close to the true tube routing
by scanning the floor surface and adjusting the reciever's gain. Utility
companies have such equipment and a friend of ours who works for such a
company says he can borrow the equipment for the experiment.
The real problem is this. Since the tubing is 200+ feet in length with
numerous 180 degree turns the chances of snaking a wire through the length
of the run is probably impossible. So here is the question.
Do you think that by filling up the tubing loop with a highly conductive fluid,
inserting a bare copper conductor (wire) into the tubing so that it makes good
contact with the solution and then attaching the signal generator to the wire
that we would be able to detect the frequency signal for the full length of the
tube by utilizing the detector?
I apologize for the lengthy description and hope that you have enough
information to get the full picture of our situation. If you have any questions
please contact me. If you have any suggestions other than what we have
thought of by all means toss them to us. We really don't want to start drilling
and then see plastic tailings coming out of the hole.
Thank you for your time, Steve.
Answer So, you want to know the routing of the vinyl tubes so that you can cut into the floor and avoid damaging the tubing. Did I get it right?
The conductive material idea and/or rf measurement is not so good in my opinion. You would have some difficulty resolving the location/position accurately. And, you may not even be able to get a reliable measurement.
Why not just drill. If you cut a line, remove a little cement material, reconnect to the PVC and route it around the hole and reconnect it on the other side in the same manner. PVC is easy to splice. That may be easier than the complicated measurements you mentioned.
But, of the ones you mentioned, I would favor the heat measuring method. They can be really sensitive. If you run hot water through the pipes on a cold day for a few hours I think you will find enough temperature differential between the pipe lines that you can feel it as you pass your hand over the floor - or measure it with a temperature gauge. That is my opinion.
