Plumbing Zone - Professional Plumbers Forum banner
21 - 40 of 42 Posts

·
Registered
Joined
·
289 Posts
Bottom line. My method worked. It took about 4 hours to find the leak, open the stud bay, fix it and patch & tape the wall.
I'll take those results any day.
Whatever works, but I have a background in cleaning aviation fuel tanks. I am familiar with Leo/Uel etc. personally I wouldn’t do it the way you did. I would prefer an inert gas like nitrogen or even just and air compressor if I couldn’t run the water.

This is a place for professional plumbers to shoot the breeze and trade tips etc. you do you and whatever keeps the food on your table.
 

·
Registered
Joined
·
289 Posts
Air could very well work but I keep a bottle of nitrogen and for a leak like the OP had I would’ve pumped it up to 500-600 psi.

If that didn’t work then no need to try an air compressor.
Maybe a dumb question, but have you ever damaged any fixtures or fill valves pumping it up that high? I get nervous going over 100psi
 

·
Registered
Joined
·
2,885 Posts
Discussion Starter · #29 ·
You both are right, air first, inert gas second. But, I was in a pinch and didn't have access to nitrogen that morning. My plumber had already tried air at 100lb+ the day before to no result (without me present). He's young with limited experience. I may have been able to make the pipe speak, but like I said, I was under the gun.
 

·
Registered
Joined
·
55 Posts
Air could very well work but I keep a bottle of nitrogen and for a leak like the OP had I would’ve pumped it up to 500-600 psi.

If that didn’t work then no need to try an air compressor.
You need to consider the pressure limitations of everything in the system that will get exposed to the test or detection pressure you are applying. 500 - 600 PSI may be acceptable in a refrigeration system, but not for most plumbing systems!
 

·
Registered
Plumbing
Joined
·
1,240 Posts
Ok, no problem. I still pump it up to 500 psi when I’m trying to make a leak whistle. I’m speaking of copper tube, not plastics.

I just isolate the fixtures by turning valves off if
Possible. If not possible I let it rip anyway.

My bottle pressure is in the thousands…..not sure exactly. I think it’s 2500 psi. I posted a pic of my gauge and bottle.

I just googled nitrogen bottle pressure and it’s between 2200-2400 psi.
 

·
Super Moderator
Joined
·
12,632 Posts
Ok, no problem. I still pump it up to 500 psi when I’m trying to make a leak whistle. I’m speaking of copper tube, not plastics.

I just isolate the fixtures by turning valves off if
Possible. If not possible I let it rip anyway.

My bottle pressure is in the thousands…..not sure exactly. I think it’s 2500 psi. I posted a pic of my gauge and bottle.

I just googled nitrogen bottle pressure and it’s between 2200-2400 psi.

I do lots of electronic leak detection and I will sometimes put nitrogen in the copper lines. But with the pressure that you're talking about, the leak must really whistle quite loud. I had never thought of that pressure. You must go through a lot of nitrogen that way. I just have a small nitrogen bottle on my van; its about the size of an acetylene B tank.
 

·
Registered
Plumbing
Joined
·
1,240 Posts
I do lots of electronic leak detection and I will sometimes put nitrogen in the copper lines. But with the pressure that you're talking about, the leak must really whistle quite loud. I had never thought of that pressure. You must go through a lot of nitrogen that way. I just have a small nitrogen bottle on my van; its about the size of an acetylene B tank.
I use to call a company named American Leak Detection. The guy was from Louisiana. He would locate slab leaks for me when the plan was to repair the pipe vs repipe through the attic with Pex.

That’s who turned me on to the high pressure. He would put on his listening device and if he couldn’t hear the leak good at 100-150 psi He would keep cranking it up to 500 psi.

I would turn the regulator for him, he would hold his thumb up or down and I would throttle up the pressure as he listened.
He was usually with 3’ of the leak. We did this probably once a month for about 5 yrs. Then he retired.

So I have an old analogue listening device that I’ve used on a few occasions to find leaks under slabs. When he retired I decided to just bypass most all leaks. I became very good at locating manifolds and finding the leaking pipe to bypass.
 

·
Super Moderator
Joined
·
12,632 Posts
I use to call a company named American Leak Detection. The guy was from Louisiana. He would locate slab leaks for me when the plan was to repair the pipe vs repipe through the attic with Pex.

That’s who turned me on to the high pressure. He would put on his listening device and if he couldn’t hear the leak good at 100-150 psi He would keep cranking it up to 500 psi.

I would turn the regulator for him, he would hold his thumb up or down and I would throttle up the pressure as he listened.
He was usually with 3’ of the leak. We did this probably once a month for about 5 yrs. Then he retired.

So I have an old analogue listening device that I’ve used on a few occasions to find leaks under slabs. When he retired I decided to just bypass most all leaks. I became very good at locating manifolds and finding the leaking pipe to bypass.


I don't want to judge the Amer. Leak Detection man who retired, but I am wondering if he needed that high pressure to compensate for low-quality listening equipment. I have leak detection equipment that lists for $3500 and I can usually get right on top of the slab leak. Once in a while I am a foot off.

I also use an infra red {IR} camera to look for leaks on hot lines under the slab. I have even re-routed hot water into a cold manifold to temporarily turn the cold manifold 'hot' for my investigation.
 

·
Registered
Plumbing
Joined
·
1,240 Posts
I don't want to judge the Amer. Leak Detection man who retired, but I am wondering if he needed that high pressure to compensate for low-quality listening equipment. I have leak detection equipment that lists for $3500 and I can usually get right on top of the slab leak. Once in a while I am a foot off.

I also use an infra red {IR} camera to look for leaks on hot lines under the slab. I have even re-routed hot water into a cold manifold to temporarily turn the cold manifold 'hot' for my investigation.
This was 25 yrs ago. He used nitrogen to make the pinhole leak louder. Some leaks are very small. I have no idea of the brand listening equipment. Also there can be noise in the environment that you can’t control.

Yes, putting hot water through the cold side is a option we’ve used before, good tactic.

We can’t make joints under the slab unless it’s brazed. Not even repairs. If it’s cpvc or pex it’s an automatic bypass because there’s no joints allowed under slabs unless it’s brazed rule kicks in.

Funny that his name was Tommy also ! 🤣
 
21 - 40 of 42 Posts
Top