Question by New Participant on Water Leak Detection

**etbrown4** · January 24th, 2012, 06:16 PM

I know this is a forum focused on locating underground utilities.

Curious to know if any participants are involved in leak detection?

If so I have some questions on some leak detection equipment - in particular introduction of helium or 5% hydrogen into water lines - where one uses a gas sniffer, above grade, to locate the leak.

If anyone is familiar with this kind of locating and detection, I'd appreciate hearing.

**orangeboots** · January 25th, 2012, 09:10 PM

Ive used helium to locate leaks in air core phone cables but not water lines. Is it not possible to use a triangulator?

**UULC** · January 25th, 2012, 09:43 PM

I am no expert on the make up (characteristic) of helium or 5% hydrogen, but you cannot introduce air into a water system. You will cause an air blockage. That is the reason you have air relief valves on water and force main.

**daman1** · January 25th, 2012, 10:29 PM

Originally Posted by UULC

I am no expert on the make up (characteristic) of helium or 5% hydrogen, but you cannot introduce air into a water system. You will cause an air blockage. That is the reason you have air relief valves on water and force main.

I think you're right. Wouldn't you have to have to purge the system of water first?

**etbrown4** · January 26th, 2012, 06:50 PM

This new process involves isolation of the water line from the water system, and then plugging each end of the pipe with inflatable plugs on the id of the pipe. If one end terminates at a house main valve etc., you can just close that main, and remove the meter on the other end.

One plug will allow the introduction of a gas like helium or 5% hydrogen. You pressurize the line up to 20 psi and then use an electronic gas sniffer to attempt to precisely locate the leak. Before pressurizing the line and adding the gas, you have theoretically got a rough location on the leak using a highly amplified electronic probe, so you know about where to sniff.

I was asking if any of you locating guys had used a process like this and then we could compare notes on different gases etc.

Thanks for any input.

**UULC** · January 26th, 2012, 08:07 PM

What size and how deep are you talking about. This must be something very new.

**etbrown4** · January 26th, 2012, 08:20 PM

Using the applied gas approach you can test any size line from 3/4 to 12", as long as you have the right size plugs and enough gas!

**orangeboots** · January 26th, 2012, 09:15 PM

Once again why not triangulate you don't have to open the system. In my area if you open the system you have to sanitize and flush it. Why go to all that work when its not necessary. I have never seen triangulation not work to within a couple feet and it would be much faster.

**daman1** · January 26th, 2012, 10:21 PM

Won't you also run the risk of springing new leaks other areas when you depressurize it?

**etbrown4** · January 26th, 2012, 10:36 PM

Originally Posted by daman1

Won't you also run the risk of springing new leaks other areas when you depressurize it?

New leaks are unlikely with this process. We're talking about 20psi for testing purposes amd all these lines are going to br rated 100psi or better.

With copper it's opten a pinhole and with pvc or polyethelyene it's often a joint.

**daman1** · January 26th, 2012, 10:53 PM

Originally Posted by etbrown4

New leaks are unlikely with this process. We're talking about 20psi for testing purposes amd all these lines are going to br rated 100psi or better.

With copper it's opten a pinhole and with pvc or polyethelyene it's often a joint.

Not the pressure of the induced gas, Its when you repressurize the line after a repair. I thought if you purge a water line, when you open the valves and return the pressure to normal, it'll bring out other weaknesses in the line if there are any. That's what the water dept guys have told me. I know that's how it works for gasket fittings and home plumbing. I assume if you're company is trying this they must have already answered these questions. I haven't actually seen it done before so......

**orangeboots** · January 26th, 2012, 11:00 PM

I'm assuming his company is selling them. I have asked twice about triangulation and he hasn't answered

**UULC** · January 26th, 2012, 11:49 PM

Orangeboots & Damen1

I have worked within the water and wastewater fields for the last 25+ years. You cannot introduce anything into the water system without chlorinating and flushing the system Then you have to have a boil water notice for the affected area until it clears the health dept test that we called the bac-t test. This is just not feasable to find minor leaks. I have and have used all type of leak equipment that are very accurate. If it is a major leak you will see it and you can use leak detection equipment to pinpoint it.

**etbrown4** · January 26th, 2012, 11:53 PM

Hey, not selling anything.

We aren't familiar with triangulation except from geometry class. Understand the principle though.

How does it work in leak detection? With the magnified sound probe we can get hopefully within 2-3' of the NOISE of a leak.

The idea of gas is to make absolutely certain the location of a leak, as opposed to just the sound of a leak with water or air gurgling inside of a pipe. It should be especially helpful over asphalt or concrete where you don't want to make cuts unnecessarily.

The way the helium gets above grade is through 1/4 holes drilled every few feet in the suspect area. The hole with the highest concentration of gas, should mark the spot.

Friendly note to the prior poster. We're told to use reagent grade helium or reagent grade 5% hydrogen. These are certified pure and are incapable of introducing bacteria, per the lab certificate. (Certainly way more so than the average plumber who cuts, and glues in a section of pipe upon finding a break.)

**daman1** · January 27th, 2012, 12:54 AM

Maybe I'd just have to see it done to understand, I just don't get how it works if you don't isolate the suspect pipes and the purge the water first. Even if you go through all the trouble of inducing gas and getting it to leach up through a break in the line, I've seen natural gas take hundreds of feet to leach up to the surface. You're right back where you started. Maybe other gasses wont do that but why go through all the trouble? It'd have to be a pretty important slab of concrete to warrant all the effort and I don't see how it'd be any more efficient than traditional methods.