Leak finding on domestic water supply's?

[Ian H]

Does anyone do this for a living?

I've been doing it for about a year now but feel I could do it better so wondered how others do it.

The obvious ones are easy, where the water is actually surfacing but the mystery ones are not so easy to detect.

I usually use a listening stick to try and hear the leak. If I can't hear it I can remove the internal stop tap and (depending on the pipe) use an inflatable detector which pressurises different lengths of pipe untill the lean is found.

If I can't use that's it's usually a case of tracing the line of the pipe with the genny or trace wire and choosing a place to dig so I can either squeeze off or cut and cap the pipe, then chase the leak from there.

It just all seems a bit hit and miss. Today I had a go with a Correlator and Seba electric listening stick, they seemed decent and I'm going to trial the stick for a couple of weeks. I'm not sure the Correlator suits me being on my own.

Does anyone do anything different or could offer any advice?

Cheers, Ian

 

[KenGMac]

1990, good evening.

I would have thought a bit of a niche market, you would need Insurance company's input?? for a larger market share?

Who knows?

OK about 25 years ago, I was involved in a Leak detection scenario, inside a MOD base, they were loosing about 11 tonnes of water a week?? [fairly large site]

We used a system where we placed a microphone and transmitter on top of the valves buried in the paths and roadways, the transmitters fed information to a "Computer of sorts, back in those days" which computed the leak or leaking areas of pipe, even back in the day this system was devastatingly accurate, every time, even picked up leaks that were tiny. it gave you a distance from the valve to the leak point, within MMs

Point here is there must be a more modern system that should be just as accurate, but? at what cost??

Having a look at the WWW there are a few sites offering these services BUT? no costs as to purchasing the equipment???

Point being Electro sound location IMO was an absolute winner, even back in the day.

Just a late night thought? how about you find and discuss with a Sound Engineer and a Computer specialist who could, just build you such a device but at a shall we say lower cost?? These days probably sending the result to your Mobile??

Ken.

 

[Ian H]

Morning Ken,

11tons!!!! The equipment you mention sounds very much like the Correlator I used yesterday. You input the size, material and length of the pipe and then put upto 8 sensors on any accessible sections.

When it starts to listen to the pipe it shows something similar to the earth quake measures (can't think what they are called this early), and the area most disrupted should be your leak. It Told me that on a 350mtr pipe that the leak is 200m from sensor 1 and 150m from sensor 2. That was £6000 but then finding the pipe was another story. Also the leak was a litre ever 30 minutes which didn't help.

All the work I'm doing is insurance work so I am busy, I just feel like I should be doing more first time fixes. Quite often I don't find the leak so have to recommend further works.

This is the Correlator:

And the digital listening stick:

There's a good chance of a phone based set up with the technology, which I thought was new, being at least 25years old!!!

Cheers Ken

 

[Ian H]

Well, first job with the fancy listener today.

First I tried with my normal retro listening stick and could hear f all. I could hear the leak pretty clear with the Seba one so had s dig and found the leak

Well almost, I'm a foot to the side so will have to lift another slab but I'm impressed with it so far.

 

[vinn]

A very interesting post and pics. You will know far more about this detection work than me but you asked for

a few options:

Electronic Amplification - which I think you have.
Leak Noise Correlation - similar to the above I guess.
Gas Detector - inject gas into the pipe and the gas finds its way to the surface, indoors or out.
Electro Magnetic pipeline detector.
Thermal Imaging Detection - for slab hot water detection leaks.
Ground Noise Probe - to drive into soft earth etc.

Many of these eqpt. Mfr's do training courses for their stuff.

My two pee is to first determine if the leak is indoors or outside, some pretty basic stuff is to:
Open & close the internal stop-tap and listen.
Sometimes the slab has a warm patch.
Check every possible outlet and exposed pipe.
Note the material eg lead, of the incoming mains.
Look for soggy ground - in neighbouring gardens as well.
Check for common supply.
Test both int and extn stop-taps before doing anything.

Its common for small builders and plumbing firms to hire a detection guy, and then do the dig themselves - the detector guys are often hired on a no leak no pay basis.

FWIW: I should imagine that in a year or so you will have built up a knowledge base to go on your own.

 

[KenGMac]

1990, good evening.

Actually impressive, almost spot on about 250 mm or 300 mm. adrift, not really too shabby?

I take it that you plonk the microphone down and get some sort of Amplitude read out on the device?

I would imaging that if you placed the mic in several positions you could in effect triangulate the source? but a lot is dependent on obstructions in the ground.

Only IMO improvement could be to take a leaf out of [hang on here] Target Rifle and Pistol shooting??

OK I must admit to be involved in Shooting Rifle and at times Pistols, Rifles are both small bore [0.22] and Full bore [0.308 -- Military version being 7.62 mm.] pistol is air weapons as well as Air Rifle, indoor and outside

So what has going BANG anything to do with your device?

At serious competition levels, including obviously the Olympics, the competition is harsh and the difference between competitors is right down to the wire so much so that the only way to differentiate between where the shot hits the target is to use Electronics, it being impossible to differentiate where the shot hits the target usinf paper or card targets and metal guages.

 

[Ian H]

Gas Detector - inject gas into the pipe and the gas finds its way to the surface, indoors or out.

Thermal Imaging Detection - for slab hot water detection leaks.

My work sun contract the gas detection out at the minute, that would usually be on a system with a few branches where there isn't an obvious leak. I'd like to be on site to see that done.

I've not heard of the thermal imaging before, would you run hot water through the system? There is a boiler at work that used to be used for curing liners in drains, that might not be a million miles from putting hot water into a supply pipe. I'll read further into that, cheers

 

[Ian H]

1990, good evening.

Actually impressive, almost spot on about 250 mm or 300 mm. adrift, not really too shabby?

I take it that you plonk the microphone down and get some sort of Amplitude read out on the device?

I would imaging that if you placed the mic in several positions you could in effect triangulate the source? but a lot is dependent on obstructions in the ground.

Hello Ken,

Yes, I wear some wireless headphones and can either attach a rod to the wire or a claw. I put that at various places so can hopefully hear the leak and also get a read out of the noise level between 0 and 99.

Are you saying with the guns that the noise of the pellet hitting the target is measured?

 

[KenGMac]

1990, good evening.

The short answer to the question is, yes, but?

There are two types of Electronic targeting systems, one is sound the other is Optical [Laser]

The sound version has three or four microphones set into the frame of the target, as the Air Rifle Pellet passes the frame and hits the target the sound of the pellet passing is detected by the Microphones, the sound source is triangulated electronically to be calculated, hey presto a really precise stirke location can be determined.

In Air weapons for example, 10 m. indoor rifle the "Bull" [believe it or not?] is 0.5 mm. Diameter, because the top shooters are really good, the 0.5 mm. " Bull" has to be broken down into Nine parts, this results in a score of anything between a 10.1 to a 10.9, obviously if the pellet does not touch the bull the next lower score is given. prior to electronic targeting, it was up to the scorers individual expertise, can you try to imaging the arguments resulting in the difference [that could be vital] in the difference between a 10.5 to a 10.7??

The laser system works on the same principal as above.

As for so called Full Bore [0.308 inch. Sporting, target --7.62 mm. military] the same basic principles as above prevail but [obviously] the dimensions of such targets are much, much larger, and hence the microphones are modified accordingly, to be honest I do not know how large the target frames are, i never bothered to inquire, I an terrified at the prospect of putting a round into the frame, if I do I will need to pay £££, I have only fired on such a range on one occasion. which has firing points from 500 Yards to 1,000 Yards.

Now where does this all lead??

If we now [obviously] transpose the general principles of Target shooting to your work, imagine having two or three microphones near a leak?

I omitted to add to my Diatribe above, when I take a shot, firing a 0.308 at 600 Yards, I get an almost instant read out on a screen at my firing point, on this screen there is a list to the right hand side that tells me what score I have achieved [using the same overall principles as for Air Weapons, that being the nine point system to define the "Bull" in this scenario the "bull" is some 7.5 inches --- after all this is 600 yards, not 10 m.] the score is followed by an arrow, pointing to the "Bull"

Imagine two or three microphones and the read out ---With Arrows-- that would take a load of guesswork out of your location issue??

If you have a look on Wikipedia, there are several sources, including a DIY version of how to make your own Microphone system, just a thought?

One final thing the reason that the full bore does not hit a steel plate is that the projectile exploding on a plate would destroy the target frame, just think? the 0.308 leaves the muzzle at Supersonic velocity??, even after travelling say 600 Yards it is not hanging about, the Impact is the mass of the projectile multiplied by the Velocity Squared !

Ken.

 

[Ian H]

I'm playing with another bit of kit today and so far it's my favourite. It's a pipe microphone that listens for the leaks from inside the pipe.

I'm on a farm with 350mtrs of pipe and no visible sign of the leak. First I put my trace wire down a 32mm pipe in one of the stables because the farmer knew that it tee'd off the main supply.

I found the tee and confirmed the leak was between that and the meter by squeezing off:

Then we cut the pipe and connected the PipeMic, on such a long run it is trial and error.

We can do 50mtrs at a time and we can trace/probe the Mic head on its own or the entire cable if we are unsure of the line. This is how accurate it is over the 50mtrs:

I'm very confident we will find the leak once we get within 50mtrs of it, on the majority of my jobs that would need a dig for access and a dig for a repair. If a modern meter is fitted I could take that off and listen from there.

Only thing it the pipe needs to be 25mm to fit the PipeMic in.

 

[Ian H]

Nailed it, really impressed with the kit:

This is the fancy bit:

When the Mic got to the leak it sounded like a jet engine. It was leaking 1 litre per minute so not a massive leak.

 

[jeff the gasman]

Good kit and an interesting post. Thanks

 

[Ian H]

This is the old school pressure tester which I'm using today. The pipe is 1/2" black alkathene so the PipeMic is too big.

We dug onto the pipe near the house and squeezed off which showed the leak was outside.

Then we connect the machine to the supply pipe and push a balloon (called a Bladder) down and inflate it, after twiddling a knob we then put pressure into the supply pipe. If the supply looses pressure you know you have passed the leak. We try and locate it to with 6" then dig and replace 1/2 a meter of pipe to make the repair.

Couple of pics:

Machine connected to the supply

The machine and Bladder hose:

The dials for the Bladder and pipe pressures, with the various valves to direct the air.

The Bladder itself

Now to dig where it says the he leak is, finger crossed.

 

[Ian H]

Found it but FFS, who puts pipes in that deep??

 

[HERTS P&D]

You do like to dig.

Andy