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Discussion Starter · #1 ·
Line was tested before sheetrock was installed. But, now it won't hold a test and we don't want to find the problem by turning on the water and possibly soaking a wall.
Anyone familiar with sniffing out leaks in walls by charging a line with nitrogen or some other gas?
 

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Helium. With a helium detector. The problem is that you have to be able to get to the space around the pipe with a helium detector. There are several types, most have an telescoping rod that works as the business end of the sniffer. I’ve been able to drill a hole in metal top plates to sniff out leaks.

Equipco in Concord, CA will have both the gas and the sniffer for rent.


I’ve also seen it done by charging up the pipe with carbon dioxide and hitting the wall with what seemed like a sophisticated stethoscope.

Good luck!
 

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Is this on Pex, Copper or CPVC (hope not) ?
If you have it narrowed down to something less than 15" of vertical run I would Isolate the section in question and use 90% Isopropyl Alcohol. It's "Wet" but dries (evaporates) almost instantly.

Had to do this on Med Gas piping that got hit with a cabinet screw. You can't "water test" Med Gas piping but the AHJ allowed 90% IPA without making us replace it.
 

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Is this on Pex, Copper or CPVC (hope not) ?
If you have it narrowed down to something less than 15" of vertical run I would Isolate the section in question and use 90% Isopropyl Alcohol. It's "Wet" but dries (evaporates) almost instantly.

Had to do this on Med Gas piping that got hit with a cabinet screw. You can't "water test" Med Gas piping but the AHJ allowed 90% IPA without making us replace it.
Woah, a 90% IPA. I bet you slept good after drinking one of those
 

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Have you considered using nail plates before the wall was sheet rocked? :ROFLMAO:

Jokes aside how long of a run is it?
And when you say it won't hold test. Do you mean you can get it to the pressure and then it slowly loses pressure. Or you can't even reach desired PSI to start the test.
 

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Discussion Starter · #11 ·
We use nail plates religiously, but doing so wouldn't have stopped this one.
Pumped the line up with propylene gas (that's all I had on the QT) and narrowed the leak down to one stud bay. Opened it up and look what we found, a nail through the exterior plywood. That's why seasoned carpenters lay out the stud widths and chalk them on the plywood. Then, if they hit a pipe it's because the pipe went through a stud, or a top or bottom plate. Unfortunately, a gun nailer will penetrate a stub plate even if it's 16 ga. And, the problem with 16 ga plates is that they form a bulge in the wall covering.
 

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We use nail plates religiously, but doing so wouldn't have stopped this one.
Pumped the line up with propylene gas (that's all I had on the QT) and narrowed the leak down to one stud bay. Opened it up and look what we found, a nail through the exterior plywood. That's why seasoned carpenters lay out the stud widths and chalk them on the plywood. Then, if they hit a pipe it's because the pipe went through a stud, or a top or bottom plate. Unfortunately, a gun nailer will penetrate a stub plate even if it's 16 ga. And, the problem with 16 ga plates is that they form a bulge in the wall covering.
Its really difficult to shield against every possable way that another person coming behind you can damage your work. Most codes have pipes at least 1-1/4' from the edge of framing that they pass through or else shield that pipe. Commercial codes usually call for 1-1/2 " clearance. You could try to practice that clearance from sheathing that is likly to get nailed into, such as when siding is going to be attached to the sheathing. Mechanical codes require shielding for refrigerant lines that are in close proximety to underside of roof sheathing to protect from roof nails and "shiners" - sheathing nails that miss the rafters. Unwanted penetrations are going to happen. Homeowners hanging things on walls, etc. Not a big fan of using flammable gases to do leak detection. Helium can be a very expensive gas but is commonly used for leak detection in manufacturing of refrigeration products. Also, pressurizing water piping above its rating could potentially damage the pipe or its connections. Many leak detection companies fill with water and back it up with a regulated pressure of compressed air or nitrogen. Many bring air in scuba tanks. Its a quiet way to intruduce it while trying to listen for the leak. I put this info out there as something that might be helpfull to others. Not intended to talk down to anyone. We should be able to share info that some may already know, and some may not.You did the install, so you probably already had in idea where pipes you installed could be in a place that was vulnerable to a nail, etc. Good job on locating this. Wide shields are called for in most codes at top and bottom plates that pipes pass through from above or below because another may come after you and install wide moldings such as crown or tall bottom moldings.
 

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Discussion Starter · #16 · (Edited)
Marty
I agree with you, helium or nitrogen would be the way to go. So did my apprentice. Unfortunately, I didn't have access to either in a timely fashion on the day in question and I was working within a tight window of time. Combustibles require two things to ignite, critical mass and an igniter. Control for either or both and you greatly decrease the danger. We made sure there were no sources of a potential spark and once we located the general area of the leak, we shut down the gas and let it dissipate and carefully opened the bay with a blower going full tilt.
 

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Line was tested before sheetrock was installed. But, now it won't hold a test and we don't want to find the problem by turning on the water and possibly soaking a wall.
Anyone familiar with sniffing out leaks in walls by charging a line with nitrogen or some other gas?

You could charge up the line with a small nitrogen bottle and using your naked ear, probably hear the hissing noise.

Or, hire an electronic leak detection company. Which is essentially the same thing. He just uses a ground microphone, with an amplifier that amplifies the sound and sends it to his headphones.

After I got into elec. leak detection, I have gotten really good at sniffing out leaks.
 
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