Tracer gas detection ยท La Mirada, CA
Tracer gas leak detection and repair in La Mirada
Tracer gas detection fills the pipe with a non-flammable forming gas and uses a hydrogen sensor to pinpoint where the gas escapes at the surface, locating leaks under slabs and pavement to within inches.
Properties in the La Mirada 90638 area generate a large share of calls for this service, typically from homes with original copper supply. Helium leak detection is the service that typically resolves this pattern.
When a leak is too slow for acoustic correlators to register, or when it is buried under thick concrete that traps vibration, tracer gas detection offers a different physical principle. A non-flammable forming gas, a mixture of 5 percent hydrogen and 95 percent nitrogen, is introduced into the isolated pipe under controlled pressure. The gas escapes at the leak point, permeates upward through the soil and concrete, and is detected at the surface by a highly sensitive hydrogen sensor. Because hydrogen molecules are extremely small and buoyant, they rise through the overlying material quickly and produce a concentration peak directly above the leak.
The forming gas
Why 5 percent hydrogen, 95 percent nitrogen
Pure hydrogen is flammable above 4 percent concentration in air, which makes it unsuitable for use in occupied spaces. The forming gas mixture holds the hydrogen at 5 percent in a nitrogen carrier, which keeps the mixture below the flammable threshold by a significant margin. This means it can be safely introduced into a water supply line in an occupied home without requiring evacuation. The nitrogen serves as a carrier and a pressure buffer. The hydrogen is the detectable tracer. At the surface, a hydrogen sensor tuned to parts-per-million sensitivity distinguishes the forming gas plume from the negligible hydrogen background in normal air.
The procedure
Isolate, fill, dwell, scan
The line is isolated by closing the upstream shutoff and any downstream valves, then drained of water. The forming gas cylinder is connected at a fill port or a hose bib fitting, and gas is introduced at the fill pressure specified for the pipe type and diameter, typically between 3 and 10 psi. The gas is allowed to dwell for a period that depends on the depth and the concrete or soil above the leak, usually 15 to 30 minutes for a shallow slab. The technician then scans the surface with the hydrogen sensor probe in a systematic grid, noting the concentration reading at each point, and marks where it peaks. That peak, corrected for any drift in the building's ventilation, is the leak location.
Slab or pavement leak that acoustic methods could not place?
Forming gas fills the line and the hydrogen sensor finds the peak at the surface.
Plastic pipe advantage
Where tracer gas works when acoustic does not
Acoustic correlators lose signal strength quickly on PVC and PEX supply lines because plastic does not conduct vibration as efficiently as copper or steel. Tracer gas does not depend on the pipe material at all: the gas escapes through the leak opening regardless of what the pipe is made of, rises through the soil, and registers on the hydrogen sensor above. For La Mirada homes with PEX or PVC supply lines, or for the copper repipe jobs where the new PEX lines were buried under a fresh concrete pour, tracer gas is the detection method that confirms the seal before the final inspection.
Setup
Cylinder, regulator, and connection
Introducing the forming gas requires a small-bore regulator attached to the cylinder valve to drop the stored cylinder pressure of around 2,000 psi down to the target fill pressure of 3 to 10 psi. A Schrader valve adapter or a hose bib connection mates the regulator outlet to the isolated pipe, and a pressure gauge at the fill port confirms that the pipe has reached the target pressure and holds it. A shutoff at the cylinder lets the technician stop the flow once the fill pressure is reached without disturbing the line. Overpressuring a domestic supply line is the main risk of the procedure; the regulated pressure is set conservatively and monitored throughout the dwell period to ensure the pipe is not stressed beyond its working rating.
In La Mirada
Slab leaks and post-repair verification
La Mirada's prevalence of slab-on-grade homes makes tracer gas one of the most used detection methods in the area. Under a concrete slab, the gas cannot escape laterally as easily as in open soil, which actually concentrates the plume directly above the leak and improves the precision of the surface reading. After a slab leak repair, tracer gas is used to verify the repair is sealed before the concrete is poured back over the line, eliminating the need to saw-cut again if the repair was not airtight. To schedule a tracer gas leak location, call (562) 488-9614.
Questions we hear
Answered for La Mirada homeowners
Is the forming gas safe to use inside a home?
Yes. The mixture is 5 percent hydrogen in 95 percent nitrogen, which keeps the hydrogen below the flammable threshold. It is non-toxic and can be used safely in occupied homes without evacuation.
How does the hydrogen sensor work?
It reads the concentration of hydrogen at the surface in parts per million and alerts when the reading rises above the background level. A concentration peak directly above a point on the pipe marks the leak location.
Why is tracer gas better than acoustic on plastic pipes?
Acoustic correlators need the vibration to travel along the pipe material. Plastic pipes dampen vibration quickly. Tracer gas escapes through the leak opening regardless of pipe material, so it works equally well on PVC, PEX, or copper.
Can tracer gas be used after a repair to verify it?
Yes, and it is one of the best uses of the method. The repaired line is pressurized with forming gas, and the sensor scans the repair zone. A clean reading confirms the seal before any concrete is poured back.
How accurate is tracer gas location?
Under a slab the concrete traps the gas plume above the leak, concentrating it and improving precision. In open soil, accuracy is a few inches to a foot depending on depth. It is generally more precise than acoustic on plastic pipe.
Related services
Other leak services in La Mirada
Helium Leak Detection
The technicians who handle helium leak detection are the same specialists you would want on acoustic leak locating.
Acoustic Leak Locating
On a slab-on-grade home where the pipe run keeps failing, non-invasive detection is a fair question at the same visit.
Non-Invasive Detection
Properties with multiple potential failure points may also benefit from non-invasive detection. The La Mirada 90638 coverage page covers the neighborhood specifics.
Leak under the slab or concrete that other methods have not pinpointed?
The line is open every hour, every day.