Acoustic vs tracer gas leak detection: what is the difference?

Full transcript

George and Dave in conversation. Every word of the episode, exactly as recorded.

George

Welcome back to the show. I'm here with Dave from ADI Leak Detection, the country's leading name in leak detection, who's here to answer your questions and provide expert leak detection advice. Dave, today's question is one I hear a lot from homeowners: what's the actual difference between acoustic leak detection and tracer gas? Because to most people, they're both just ways of finding a hidden water leak.

Dave

Right, and that's a fair starting point, because both methods do find hidden water leaks. But they work in completely different ways, and they're suited to different situations.

George

So let's start with acoustic. How does that actually work?

Dave

Acoustic leak detection works by listening for the sound that escaping water makes when it leaves a pressurised pipe. Water under pressure produces a very specific noise as it forces through a crack or a pinhole, and that noise travels along the pipe and into the surrounding ground or structure. Our engineers use ground microphones and electronic listening equipment placed on the floor or directly on the pipe to pick that signal up. The equipment amplifies it, and we can trace where the sound is loudest, which tells us where the leak is.

George

So it's literally listening to the pipe?

Dave

Essentially, yes. Acoustic equipment detects the vibration caused by water escaping under pressure. It works brilliantly on supply pipes, because those pipes are always pressurised. If you've got a leak on a cold mains feed or a central heating flow pipe, acoustic detection will usually find it quickly and accurately.

George

And when wouldn't you use it? Because I'm guessing there are situations where it doesn't perform as well.

Dave

There are, yeah. Acoustic detection depends on the leak being on a pressurised pipe and producing enough noise to read. Under a thick concrete slab, for instance, that signal can get absorbed and become very weak. And if you've got background noise from traffic or other pipework nearby, it can be hard to isolate the leak signal. That's where tracer gas becomes really useful.

George

Tell me how tracer gas works then, because I think that sounds quite exotic to most homeowners.

Dave

It's not as complicated as it sounds. Tracer gas leak detection works by first depressurising the pipe and then filling it with a mixture of nitrogen and hydrogen. That gas mixture is completely harmless and non-flammable. Because the molecules in the gas are extremely small, the gas escapes through even the tiniest crack in the pipe, migrates upward through the floor or ground, and reaches the surface. Our engineer then uses a sensitive gas detector probe, scanning along the floor above the pipe run, and the probe picks up where the gas is coming through.

George

So the gas is basically marking the spot.

Dave

Exactly. Tracer gas pinpoints the leak location on the surface, which is where we need to excavate or lift a floor covering. It's particularly effective under solid concrete floors, under tiles, and in situations where the pipe has very low pressure or isn't pressurised at all, because acoustic equipment needs that pressure to generate the sound signal. Tracer gas doesn't rely on pressure in the same way.

George

So if I had a leak under a tiled bathroom floor with a thick concrete screed, you'd go for tracer gas over acoustic?

Dave

We'd look at the full picture first, but yes, that kind of situation often calls for tracer gas. Concrete and tile absorb the acoustic signal, so it becomes very difficult to get a clear reading. Tracer gas travels up through the screed and through grout lines and gives us a precise location. The whole point of choosing the right method is to find the leak without pulling up more floor than we have to.

George

Do ADI engineers ever use both methods on the same job?

Dave

It does happen. On a complex property, you might have one pipe run where acoustic detection gives a strong signal and another section where the construction makes it difficult to read. In those cases, we'll use acoustic to narrow down the area and then tracer gas to confirm the precise point. Using both methods together gives us much higher confidence before we recommend any excavation work.

George

That's really useful to know, Dave. So the short version for homeowners is: acoustic detects the sound of water escaping from pressurised pipes, and tracer gas traces where gas surfaces through the floor to mark the leak point, and which one gets used depends on the pipe, the floor construction, and what signals can actually be read on that particular job.

Dave

That's it. Neither method involves any guesswork and neither requires opening up floors until we know exactly where we're going. That's the whole value of having specialist detection equipment rather than just starting to dig.

George

Dave, thanks very much. If you've got a suspected hidden water leak at home, ADI Leak Detection are the specialists to call, with the experience and equipment to find it accurately and with as little disruption as possible. We'll be back with more questions soon.

How this episode was made. This episode was produced using AI-generated voices and script, based on real leak detection questions and the working knowledge of ADI Leak Detection engineers. More about how the podcast is made.