Transmitting a signal from INSIDE a metal pipe

[jellison2]

Hi all,

This is my first post and i'm not sure if this is in the right sub-forum but I have a slightly unusual request.

I'm trying to figure out a way to trace the path of a fairly large (50mm/2") buried iron/steel pipe. I can get access to the pipe to push something along on a flexible rod. Does anyone know any way of transmitting some kind of signal from within the pipe that I can then trace above ground?

The depth is from ground down to approximately 2-3 metres (6-9 feet). I'm not sure what other pipes are buried nearby so tracing just from the surface isn't really accurate enough - ideally I need both a transmitter and receiver.

Any ideas?

Thank in advance.

 

[n4yek]

http://metaldetectingforum.com/images/smilies/Diggin_a_hole.gif
Just kidding...

The problem with your idea is that it wouldn't be precise, if you did receive a signal you would most likely not be able to be able to locate it very accurately.

Utilities use a device like this, there is a box hooked to an exposed part of the line that generate a magnetic field. The handheld unit is basically a sofisticated metal detector that will show them the location of the line underground.
http://www.geotekservices.com/wp-content/uploads/2011/08/EMI-pic.png
http://www.geotekservices.com/wp-content/uploads/2011/08/util.png

 

[kayn1n32008]

Hi all,

This is my first post and i'm not sure if this is in the right sub-forum but I have a slightly unusual request.

I'm trying to figure out a way to trace the path of a fairly large (50mm/2") buried iron/steel pipe. I can get access to the pipe to push something along on a flexible rod. Does anyone know any way of transmitting some kind of signal from within the pipe that I can then trace above ground?

The depth is from ground down to approximately 2-3 metres (6-9 feet). I'm not sure what other pipes are buried nearby so tracing just from the surface isn't really accurate enough - ideally I need both a transmitter and receiver.

Any ideas?

Thank in advance.

I locate buried pipe/survey for a living

If you do not know where the pipe is, call a locating company. They have the right tools for the job. Locating takes years to learn correctly, and is not just as easy as following a signal.

Most companies in Alberta require minimum 1year holding the transmitter before they let someone operate the receiver.

Locating is not exact, and is subject to interference from other pipes, and ferrous materials that maybe nearby. My best advice is to hire a locating company.




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[KF5YBZ]

You'll need a good two-box metal detector and someone that knows how to use it. Even then, 2" pipe at 2 meters is pushing the limits, but definitely possible. Maybe you can rent one or better yet find your local metal detecting club as most members will volunteer their services for free. Might even try lostmystuff.net. I was a volunteer there for a few years, they mostly find and return jewelry, but someone will likely come out of the woodwork with a two-box.

 

[kayn1n32008]

The problem with your idea is that it wouldn't be precise, if you did receive a signal you would most likely not be able to be able to locate it very accurately.

Utilities use a device like this, there is a box hooked to an exposed part of the line that generate a magnetic field. The handheld unit is basically a sofisticated metal detector that will show them the location of the line underground.

While this answer is partially correct, it is much more complex. The transmitter usually (on high end locaters) operate at frequencies from 512Hz(yes Hz) to almost 500KHz.

As stated in the post above the transmitter does not have to be connected to the target.

Good receivers have 4 receive antennas, 2 are used for peak signal strength, and 2 are used for null or zero signal strength, using all 4 antennas allows the receiver to display direction to the conductor. Some higher end locators also have the ability to display the orientation of the conductor relative to the receiver

The transmitter, when used inductively has a VERY directional antenna, there are techniques that allows one to find pipes, inductively, that are very close together.

The system, both transmitter and receiver, is not a metal detector at all. A pipe locator uses RF to induce(light up) an RF signal into the pipe, and using VERY directional antennas, find the signal. The antennas are so directional that I can be less than 1 metre from my transmitter and completely null the signal just by changing the orientation of my receiver.

The type and size of the pipe dictates the frequency you use

A small pipe 50-300mm, is easiest to find with frequencies between 27KHz and 83KHz

A large pipe 300-1300mm must be found using frequencies below 27KHz.

Size also dictates how far a pipe can be located. A 50mm pipe using 512Hz can fe followed, directly connected, for man many kilometres where as that same pipe may only be followed for hundreds of metres when using 200KHz under the same conditions.

While this explanation is VERY basic, locating buried facilities is VERY complex, and there are MANY more factors than listed above.

To be able to competently locate buried facilities takes years of training. Most importantly a competent locator knows what the limit of his skills and what is and is not locatable.






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[kayn1n32008]

You'll need a good two-box metal detector and someone that knows how to use it. Even then, 2" pipe at 2 meters is pushing the limits, but definitely possible. Maybe you can rent one or better yet find your local metal detecting club as most members will volunteer their services for free. Might even try lostmystuff.net. I was a volunteer there for a few years, they mostly find and return jewelry, but someone will likely come out of the woodwork with a two-box.

Actually a 2" pipe at 2m is EASY to find. I do it every day I am at work. The OP needs a Pipe locator and competent operator, not a metal detector.

This image is of a site I located this year, there are more than 60 pipes coming into this site, most being at or below 2m and VERY close together.


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[KF5YBZ]

Have to disagree as I have personally seen it done several times. One of my detecting buddies is retired water department and he could have that pipe staked out in minutes, as I am sure others competent in the use of a two-box could. Good luck to the OP whether you take the free road or the toll road.

For instance... http://www.kellycodetectors.com/fisher/tw-6.htm

 

[kayn1n32008]

Have to disagree as I have personally seen it done several times. One of my detecting buddies is retired water department and he could have that pipe staked out in minutes, as I am sure others competent in the use of a two-box could. Good luck to the OP whether you take the free road or the toll road.

For instance... http://www.kellycodetectors.com/fisher/tw-6.htm

What you linked to IS a pipe/cable locator. Albeit a cumbersome looking device, you use a Slightly different name for it but it operates on the SAME principle as I explained above. It dos not detect metal, but detects the RF signal you induce into a conductor...

This:

is a metal detector. This machine detect the Magnetic field present in ferrous materials.

This:

is a pipe/cable locator. It uses RF to light up any kind of conductive metal. This is the equipment is what puts food on my table... I have located everything from fibre optic cable to 1000mm pipe with it.

This is my bread and butter. I used the above pictured locator to locate the pipes staked in the above picture I previously posted.

Seriously I do this EVERY DAY professionally, for a living...

To the OP: Unless you know someone that does this professionally, HIRE someone that is competent to locate the line in question and any others in the area. If you are doing ground disturbance, and you hit something you WILL have to pay to repair it. The couple of hundred dollars to do a proper locate can save you thousands in emergency repairs ( hitting a fibre-optics line will cost you tens of thousands of dollars for the repair and the sky is the limit in lost data the owner will bill you for ) Worse consequences if you hit a high pressure gas line, and it ignites... You are now talking about lives and they are priceless.

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[KF5YBZ]

It dos not detect metal, but detects the RF induced into a conductor...

Which is what every metal detector does. Lower conductors (gold/iron) respond better to higher frequencies. Higher conductors (silver/copper) respond better to lower frequencies. The end result is locating metal.

 

[kayn1n32008]

Which is what every metal detector does. Lower conductors (gold/iron) respond better to higher frequencies. Higher conductors (silver/copper) respond better to lower frequencies. The end result is locating metal.

Yet I can find ghost signals in salt contaminated ground, yet there is not a metal object there to find....

Again I do this for a living.


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[KF5YBZ]

Yet I can find ghost signals in salt contaminated ground, yet there is not a metal object there to find....

Again I do this for a living.


Sent from an unknown place...

Maybe not an object but at the very least a concentration of disintegrated iron enhanced by salt. Us amateurs call that the halo effect. That is also the reason most amateurs choose to use Pulse Induction detector on saltwater beaches. No one wants to dig ghost signals that break up into nothing once dug and then the signal disappears. That is why higher end amateur detectors not only use conductivity to locate targets but also display the ferrous content to keep from digging rust and old iron.

 

[jellison2]

Hi all,

Thanks for the varied replies so far. I probably should have clarified my requirements a little better at the start - i'm looking to build something that I can push along inside the pipe behind a camera (ie. something smaller than 50mm diameter).
I then need to find the exact location of the camera (and if possible - I know this is further pushing it - the depth of the pipe at that point).

I don't mind spending a decent wedge of money on this but for various reasons it's not really practicable to bring someone else into do it...