How do I work out which pipe is flowing?

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Offline thedoc

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How do I work out which pipe is flowing?
« on: 06/07/2016 11:50:01 »
Christopher Lowe asked the Naked Scientists:
   3x 1" PVC pipes buried 6" below grade in loose soil, all 3 are lawn irrigation pipes, one has fewer heads towards the end of the run and I want to add two heads further upstream to this one of the 3 pipes, (the one with the fewest heads) how can I detect which of the 3 is active or flowing water in the middle of the run, not being able to follow the pipes from source to end?
These pipes lay in the same trench with 1" of separation.
I'd rather not cut all 3 to find the one I want.
What do you think?
« Last Edit: 06/07/2016 11:50:01 by _system »

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Offline cornemuse

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Re: How do I work out which pipe is flowing?
« Reply #1 on: 13/07/2016 16:38:06 »
Are these 3 pipes shallow? Irrigation usually shallow.

Water (here anyway) is quite a bit cooler from water main/deep pipes.

If you can turn all 3 on at once, the one cooling off the quickest is prolly the one flowing the most water, , , ,

-c-

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Offline Colin2B

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Re: How do I work out which pipe is flowing?
« Reply #2 on: 13/07/2016 17:46:07 »
if you can get someone to turn them off suddenly you might be able to feel the jolt if you are holding the pipe.
If you have a metal rod or broom handle hold one end against pipe other against ear you can often hear water flowing.
and the misguided shall lead the gullible,
the feebleminded have inherited the earth.

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Offline Tim the Plumber

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Re: How do I work out which pipe is flowing?
« Reply #3 on: 13/07/2016 19:32:21 »
You can get freezer machines which will freeze the water in the pipe when there is no water flowing but I have never tried this through a plastic pipe. Probably would take a lot longer.

Then you could work out which pipe fed which outlets.

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Offline evan_au

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Re: How do I work out which pipe is flowing?
« Reply #4 on: 14/07/2016 04:11:26 »
Could you inject some harmless colored food dye into the existing pipes through the existing heads (against the existing water pressure)?

Then see which other head(s) have the food dye come out?

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Offline Colin2B

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Re: How do I work out which pipe is flowing?
« Reply #5 on: 14/07/2016 08:26:46 »
Could you inject some harmless colored food dye into the existing pipes through the existing heads (against the existing water pressure)?

Then see which other head(s) have the food dye come out?
Evan has given me an idea.
Turn off water to the heads, get hosepipe and unscrew a head, poke hose down pipe and seal with hand, see which heads water comes out of.
and the misguided shall lead the gullible,
the feebleminded have inherited the earth.

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Offline Alan McDougall

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Re: How do I work out which pipe is flowing?
« Reply #6 on: 14/07/2016 09:03:59 »
Christopher Lowe asked the Naked Scientists:
   3x 1" PVC pipes buried 6" below grade in loose soil, all 3 are lawn irrigation pipes, one has fewer heads towards the end of the run and I want to add two heads further upstream to this one of the 3 pipes, (the one with the fewest heads) how can I detect which of the 3 is active or flowing water in the middle of the run, not being able to follow the pipes from source to end?
These pipes lay in the same trench with 1" of separation.
I'd rather not cut all 3 to find the one I want.
What do you think?

As an engineer, I could establish whether there was water flowing in a pipe just by looking at the amperage gauge. When there was liquid flowing in the pipe the gauge would always show the pointer in the positive because of a reaction in the pipe to a meduim.

The electric motor reflects when it is straining against something real inside the pipe. If the pipe were empty, the pump impeller would just revolve unimpeded, which would require almost no energy from the pump motor and the amperage gauge would hardly move off the indicator start point

 Forgive me if this is not the answer you were looking for!

Alan
The Truth remains the Truth regardless of our beliefs or opinions the Truth is always the Truth even if we know it or do not know it (The Truth remains the Truth)

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Offline Colin2B

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Re: How do I work out which pipe is flowing?
« Reply #7 on: 14/07/2016 09:13:38 »
Could you inject some harmless colored food dye into the existing pipes through the existing heads (against the existing water pressure)?

Then see which other head(s) have the food dye come out?
Evan has given me an idea.
Turn off water to the heads, get hosepipe and unscrew a head, poke hose down pipe and seal with hand, see which heads water comes out of.

Just realised, you could also try taking off one of the heads, turn on water then cover open end of pipe with hand, the other heads on that pipe should show variation of height. Will work better if only one pipe on at a time if they come from a common source.
and the misguided shall lead the gullible,
the feebleminded have inherited the earth.