water leak detection 3

[WaterGIS]

Hi
We are planning to have a leak detection system for water pipes ( distribution network) using helium , dose any one know more about it and how to reduce the cost of it.

Regards,

 

[NGiLuzzu]

WaterGIS,
my sensation is that helium leak detection is too much for water piping!

As far as I know, the main application field of this type of testing (which includes many methods and/or techniques) is Aeronautics and Tanks testing; then it was extended to valves, too, but problems are not absent: as a confirmation, just take a look at the large number of discussions within this forum about Fugitive Emissions testing (Thread124-48813 and Thread408-48808), devices (Thread408-112551), standards (Thread408-100721 and Thread408-90905) and specifications (Thread408-64093, Thread408-83628 and Thread408-93211), etc...

In general terms, helium leak testing is applicable when a possible even small leak would cause serious danger (is that your case?) and/or when very toxic, polluting or explosive fluids are involved... If you refer to the never-ending ISO standardization work about this matter, for instance, you must notice that ISO CD/15848-1, in the NOTE to § 3.1 states that: "... Valves used in water or in air services do not need fugitive emissions testing".

If you still want to use a tracer gas, must add that I also heard about hydrogen leak detection systems, used for underground gas piping: maybe that's less expensive... try searching the web for it!

In any case, I'd suggest to look for alternative methods for leak detection in water systems...

Hope this helps, 'NGL

 

[WaterGIS]

Hi we have water distribution network, the Value of water in our area is very important, though we have high NRW percent.
I search the web and i found this

http://www.radiantpanelassociation.org/i4a/pages/index.cfm?pageid=142

I think it is very useful, the capital cost maybe expensive but the running cost is very low and the results is 100%
For the hydrogen I did not think of it before. But i think that it may not work since that it will be dissolved in water, on the contrary the helium will not.

Regards,

 

[BobPE]

WaterGIS:

What do you mean when you say "water distribution network?"

If you are responsible for leaks in peoples homes, helium may be usefull for those tough to find leaks, but I doubt the return on the investment for these small leaks will be worth it to a water purveyor. A plumber needs to find these leaks as they will cause problems with the project they are working on, not because they want to save a few gallons of water.

If you are proposing testing your distribution system, I suggest checking the price of helium, this will give you a better picture of the investment needed for 4, 6, 8-inch and larger mains. A typical good distribution system runs with anywhere between 5 to 15 percent unaccounted for water. Finding all the leaks (100%) would be nice, but once found, you will go broke fixing them for the relativley small amount of water saved.

I would recommend getting a good water engineer to assist you in understanding the value of keeping your water from leaking vrs. reducing your unaccounted for water to such an extent that you have no return on investment. Water is scarce everywhere in the world, but quality water suppliers are even more scarce.

BobPE

 

[NGiLuzzu]

WaterGIS,
I suspect I do not understand what type of piping system you want to fill and test with helium: e.g. what diameters? What length?

The interesting web-page you found deals with "radiant panels" for heating and cooling... and then with geometry and dimensions quite different from a potable or industrial water distribution network (or, at least, so it seems to me).
Then, the web-page itself says that the helium method "can be used (...) when other detection systems fail".

Finally, why hydrogen will be dissolvend in water and helium will not? I don't feel so... but, in any case, what would be the matter with that, as you must run the test with the pipe empty of water and full of gas?

Bye, 'NGL

 

[monkeydog]

WaterGIS,
Helium mass spectrometer leak detection seems like a bit of overkill to me. The biggest problem with using helium mass spectrometer in a piping network, is phantom leaks. A slight leak (in terms of He Mass Spec) may result in helium atoms floating around in external piping network, resulting in a false leak indication. Another problem is if you have a massive leak, the general area is then flooded with helium, and purges, vaccums, etc. must be accomplished prior to isolating the leak and moving on.
There are other methods such as good old fashion bubble leak testing, or pressure decay. As other posts have stated, you probably want to determing how much water leakage you can live with, then specify the best leak test method.
If you can, get your hands on a copy of American Society for Metals (ASM) Metals Handbook vol on Nondestructive Inspection and Quality Control (Vol 17 in current edition). This handbook has a chapter on leak testing which is an excellent resource for determining leak test methods.

 

[WaterGIS]

Thank you all.
What we are working on is portable water, it distribute water for the whole state, with dimension range from 600mm to 63 mm with more than 700KM. we are planning to test the pipes while it is full of water ( while it is operated ) some of the pipes are more than 10yrs old... the helium will be injected to the water with same pressure.
I agree that it will be exaggerate the small leaks, but still micro leaks are very important. We have a NRW% more than 35%. And we think this will help us in reducing it to less than 15%. We are having water from a source that is far from our city 80km, and after awhile we will reach the max allowed capacity of water that we can have. So this will help in delay for our future search for water.
The helium is available in natural air with 5ppm. And it is inert gas that will not affect water.

 

[BobPE]

anegri stated a clear problem to testing the mains full of water, you will need to dewater the mains for any hope of getting any data that may help you. Another concern with use on larger diameter mains is that you will be sensing helium everywhere, which will kinda defeat trying to pinpoint any leaks you may encounter.

Are you getting consulting help with this idea? If so, from whom? (an engineer, salesperson, university?) It seems like a fore gone conclusion that you are going this way. So you may be able to help us in the near future to understand other reasons why it is not the best way.

BobPE

 

[NGiLuzzu]

WaterGIS,
yes, "helium is available in natural air with 5ppm" (or about 2 * 10^-6 mbar*l/s... I think that's the same also in underground air) but, when measuring for leaks, this represents a "background noise"; for this reason, to have an accurate detection, you must use high concentrations of He₂ in your tracer gas mix (ideally commercial pure Helium: more than 99%).

Anyway, your description intrigues me: have you laboratory tested the gas-in-water method already?
And what about costs estimations? What is the difference (or the ratio) between the cost (for meter of pipe) of this type of testing and the cost of pipe replacement, for instance? (Does it depend on the ND, on the pipe depth, etc.?)

The whole thing sounds like... a "new frontier": let us know about its developments ;-)

Thanks, 'NGL

 

[hydrae]

WaterGIS
The most effective way of looking for leaks in water distribution systems is to listen, most leak detectors use sound to locate the leaks. Use system pressure to make the sound.
First listen to every contact point available meter, valve, or hydrant
Then use a ground probe to pinpoint the leak or use a correlator to pinpoint the leak.
When thoose methods fail to find the leak then use the helium method, it does require the pipe to be dewatered. it also requires the area above the pipe is not sealed by pavement.
An alternative to helium and water, is compressed air, again listen for sound, the sound is different with compressed air thus may be more easily heard.
Caution: with both air and helium as they are gases, the compress gas hazard is there and in piping that is not designed to contain gases.

The only time I have seen the helium method used was on a new water main and the pressure test would not hold. The leak was a split and rolled gasket and the gasket absorbed the sound so it could not be heard, the leak was less than a 1/4 gpm, the acceptable leak rate for this new pipe was 1 gph or less.

The bigger the leak the more noise it makes. It is amazing what you can hear by just putting your ear on the pipe.

Hydrae

 

[WaterGIS]

Hi
We are planning to use this technology and company will help us in this, the water pipes dose not need to be dewatered, the helium will be pumped with water in the same pressure.
We have sounding equip. but the problem is in the technicians, it was very difficult to them to distinguish the voices (water, electricity, leakage, other voices) ... we have good equip for sounding.
In the case where pipelines are covered by asphalt you will have to drill a small hole every 10m and detect the helium.

I think that we may face a problem in micro leaks, and the cost of digging and repairing especially when the pipes are deeply located and covered by asphalt should be considered

 

[BobPE]

I take it you are not testing for a leak in a house plumbing system then. Another good question I would have is, you are relying on a company to do this for you? Is this being done so at the advice of your engineer? If you wre asking for my opinion, I would tell you YOU are wasting your time and money. I will bet the COMPANY you are using will disagree with me. But then again, unfortunately, I am an engineer, so I undrestand what they intend to do, and why it would be a waste to you. I would recommend that you get a good water engineer to assist you in your leak detection program, I guarantee you will be happy with the results....

BobPE

 

[semo]

WaterGis

35% is a large amount of unaccounted for water. I would bet that micro leaks are not the problem. I also imagine this helium testing will be extremely expensive as mentioned before; thereby, not being cost effective. You know the cost factors for this system though.

I would first start with obvious sources of unaccounted for water. You might have already done this; but, some other sources could be:

-faulty meter readings. Main supply meters and individual sales meters. Randomly test some of the meters.
-illegal connections or forgotten connections.
-inadequate documentation of flushing or fire use.
-miscellaneous unmetered treatment use (chem feed, sanitary supply, backwashing, etc.)

Once these are accounted for, then leaks would appear to be the problem. I agree that sound is the most common method of detection and the local Rural Water Association can probably help you.

Adding a gas into the liquid lines would concern me. The forces and water flows are not normal and getting the gas out of the line could pose a problem depending on the system.

 

[svanels]

Helium, overkill for water, my boss would asked what I smoked the night before.
Use a portable ultrasound detector (uesystems or others). We use it detect leaks in our steam, compressed air, water lines etc..

700 km of piping? 80 km of the source? Check for illegal connections. Are there new construction sites along the pipe line track with heavy equipment? They can burst a pipe easily.
Years ago when we were driving to and from work we were recording every escavating activity of farmers and others along side the road. If the telephone was dead, the utility company would know were to look.


In the former USSR they regularly found illegal connections on the oil pipelines entering a complete refinery.

The explosions on the shell pipelines in Nigeria about two years ago were caused by some smart a.. looking for cheap gasoline.

Steven van Els
SAvanEls@cq-link.sr

 

[WaterGIS]

Yes Helium for water, why you are shocked???
I have seen the test done in two areas and the results were excellent, but the main problem (in my opinion) that you will find micro leak and if u don't have enough budget you will have problem.
But in case that your network is new and u have enough budget then u will go to the right procedure (Helium), because the running cost is low and u will monitor your network in a perfect way.
In areas where water scars micro leaks are very important.
Hopefully we will apply this technique in our company soon. And I will provide u all with my own experience.
I just want to share others experience whom used this technique before.

Regards,

 

[BobPE]

I think what peole are trying to say WaterGIS is that we, here on this site, are an excellent cross section of the water business. If we are not on board with the approach, then there isn't much chance that any others will be on board.

We are not arguing that the approach will not work, but the return on investment just isn't there when compared to other technology that is cost effective. But who are we to say that that last 5 percent of leakage isn't important to some.

Do let us know how you make out....

BobPE

 

[WaterGIS]

thanks alot for you sport, me two new to this technology, i have found something about Hydrogen gas detection method,

(( Identifies leak position by detecting the location of hydrogen gas which has been introduced into the water supply. The hydrogen gas (carried in 93% nitrogen) rises to the surface above the leak position. Due to the small size of hydrogen molecules the gas can permeate concrete, asphalt etc. Provides accurate leak location as the gas rises above the break in the pipe.))
Limitations:
Best suited to locating leaks on smaller pipes (ideal for difficult supply pipe leak locations). Pipework is de-watered by the introduction of the gas. Gas needs to be introduced by using either a boundary meter box and forcing the gas toward the property or closing the boundary connection and introducing the gas through the customers internal stop tap. Can take some time to set up and for gas to rise to surface for detection.

for us the cost of water we loss is 10000$/day so if we implement any technique that will reduce this value, we will have a good return on that investment.

If any one has a good experience in any technology that will help to reduce the NRW effectively, please advice.

 

[unclesyd]

You have several avenues of approach. This is one type service a utility could use.

http://www.util-locate.com/leaks.htm

There are quite a few ultrasonic systems for detection of leaks in swimming pools and pipes available in most localities .

You might give these people a call and see what available in the Ultrasonic line also they have service companies located around the country.

http://www.uesystems.com

You might also want to do a search on Google “underground leak detection” Lots of good information including He leak detectors. You will find several exotic approaches to any leak problem.
We had three portable He leak detectors and 2 ultrasonic probes that we used for leak detection. Water and twice for the telephone company on an old N2 filled coax.

 

[WaterGIS]

Thanks unclesyd for your advice, did you use the helium before, what is your experience in that? Do you know any website about leak detection using helium for the portable water?? Can you please send me some of these, I will highly appreciate.

 

[unclesyd]

Do a Google search using the following: "helium pipe leak detection"
Here are just two of many sites that showed up.

http://www.medivactech.com/heliumleaktestingref.htm

http://www.heliumleaktesting.com/general/study.htm

The potable water line we found a leak in was a 4" Cu, yes they did use Cu, that came off a 12" header and went under one the edge of one building into the basement of another building. Our normal water pressure was 60 psig so we valved off the section and let the pressure drop to 10 psig and stated injection of 100% He and immediately started sweeping the ground using two portable He Leak Detectors made by Marks, built for use in finding leaks in Coaxial cables. They have a rubber cup that attaches to the hand held probe. We were able to get an indication of He about midway of the building where the line was supposedly 4' under the edge. A mining operation revealed the line to be about 6' under the edge and 7' to 8' deep. Inspection revealed the line to be in such poor condition that it was abandoned and overhead line installed. The pipe trench fill was, sandy clay.

The Marks portable detectors are no longer made though suitable replacements can be rented or leased. The portables done the job though we had two mass specs, a Leybold Hereaus and an Edwards available.