Methods of Searching for Compressed Air Leaks through an Underground Mining Piping System 1

[Fyokou]

Greetings,

First time poster....I hope this is the right location to post.

I have a Underground Compressed Air System (max psi 100) feeding various areas in a 1000m deep mine. Think of it as 10" Victaulic Piping "spidering" everywhere around the Underground Area.
I know it is impossible to a have a system that doesn't leak however what are ways in your opinions to troubleshoot the system to find leaks?

Examples I was thinking:
- Using flowmeters when there is no demand to determine how much leakage is occuring. Maybe add some instrumentation at major usage areas to determine the location of the major leaks.
- Using a directional microphone to listen for leaks (preferably during a shut-down).
- Train mining personnel to complete walk around checks for any leaks in the area before they work.

Any other ideas or experiences with Compressed Air Systems?

Thanks,
Fyokou

 

[MikeHalloran]

I wouldn't bother with flowmeters; there's not enough of a turndown to help with leak flows. You could put tiny flowmeters around closed isolation valves, but I wouldn't expect them to last a week in a mining operation.

You can get a rough idea of the actual leak flow by recording compressor cycles during a shutdown. If you've got isolation valves for particular floors, etc., you may be able to achieve some spatial resolution, e.g. by closing all but one and measuring compressor cycles etc.

I once spent a couple hundred bucks of company money on an ultrasonic leak detector microphone. The assertion was that it divided the frequency of the leak noise and presented an audible tone in supplied headphones. It worked great with the included cal/test device, basically a nasal atomizer with no liquid. I couldn't get sensible results out of it when looking for actual leaks, but my situation then was much different from what you face now.

I'd suggest the first step is to (observe all safety and lockout rules and) tour the mine during a shutdown, just listening for leaks with your ears. If you're losing commercially significant quantities of compressed air, it shouldn't take sophisticated instrumentation to detect and localize it.


As for using the mine's workforce to report leaks, it depends on the attitude of the workforce, the company's level of hostility with their union, and how you administer the program. Honestly, as perceived by the workforce, works best.

A simple poster might make a difference. Recognize that a leak represents a cost to the company, but don't depend on altruists. Offer a small reward, like a Big Mac or a beer. Bigger rewards might produce fights. ... and might induce new leaks to appear, so to speak. It's important to respond quickly to any report, to show that you are serious about the issue. It may help to assign the more vocal members of your maintenance crew to the leak repair team, so they will make an appropriate fuss about, and thereby minimize the number of, false reports.

If you decide to go ahead and involve the workforce, and make any progress by doing so, it wouldn't hurt you to buy Big Macs or beers for all of them to celebrate the achievement.











Mike Halloran
Pembroke Pines, FL, USA

 

[cvg]

use a sprayer filled with soap water. spray each fitting and look for the bubbles. this will work on leaks much smaller than what you can hear.

 

[IRstuff]

If the leaks are small, then soap bubble test might be the only meaningful way to hunt them down. If they're sufficiently large, you might be able to detect pressure losses; if there were no leaks, the entire system would equalize to a single pressure value if there were no flow.

TTFN
faq731-376

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[Fyokou]

Thanks for your input guys,

I think I'll get the miners to complete a tour of the mine during a shut-down to find leaks. Maybe find a summer/fall student to do it for me to save on cost ;-). I'll talk to corporate to get an incentive going...I'm sure they will do it since compressed air leaks is a huge cost to them (we already have a safety incentive). Too bad the mine site is a dry camp... looks like Big Mac's it is.

Recording the flowrates will be good too since I can trend major changes in airflow and inform the miners when something is wrong.

I heard of soap bubble testing as well...might be hard in some locations since the piping is on the back of the drift 7m high but nothing wrong with bringing a soap/water spray bottle with you.

Thanks again,
Fyokou

 

[Latexman]

While they are close enough to find the leaks, maybe they should have the resources, tools, gaskets, and spare parts with them to stop the leaks!

Good luck,
Latexman

Technically, the glass is always full - 1/2 air and 1/2 water.

 

[Fyokou]

Indeed! Most of the time though when we find the problem we tag it first then inform the maintenance crew and they repair it. Can't always steal maintenance's job.

 

[miningman]

Shut down ??? In 35 years underground, with the exception of fatality investigations, I dont think I've experienced a single shutdown in my life. Production is the name of the game 24/7/365. And a dry camp implies its a flyin operation so production goes right thru , xmas day included!!! Fix the obvious noisy leaks, forget the rest, unless you can isolate complete levels that are not in use, which I know is extremely unlikely

 

[cvg]

have to agree with miningman, the mine runs non-stop through LOM, 3 shifts a day no exceptionse. the only possible exception might be if there is a general union strike, in which case there would be nobody to check for leaks.

 

[dcasto]

SF6. If you can get it. Then walk the line looking for leaks. The sf6 need only be injected in ppm. Rates.