Ultrasonic Leak Detection: Finding Compressed Air and Gas Leaks is a condition monitoring technique that uses handheld ultrasonic detectors to find leaks and other faults by listening for the high-frequency sound they produce, above the range of human hearing.
When a compressed gas escapes through an orifice, a cracked fitting, or a worn valve seat, the flow becomes turbulent at the point of restriction, generating broadband acoustic energy that extends well above what a person can hear. That energy is strong and highly directional at close range, so it is easier to pinpoint than the faint hiss a person might catch near a large leak. Small leaks, leaks in noisy areas, and leaks behind guards or up in pipe racks are usually inaudible to the ear but still radiate a clean ultrasonic signature. A handheld detector uses a directional sensor to pick up that energy, then shifts it into the audible range so a technician can hear it through headphones while watching a signal-strength display. Ultrasound attenuates quickly through air and solid barriers, so the signal drops off fast with distance, letting an operator home in on the exact leak point.
Compressed air is one of the most expensive utilities in a plant per unit of energy delivered, and unmanaged leakage is consistently one of the largest sources of waste in a compressed air system. In plants with no leak management programme, it is common for a substantial share of total generated air, often cited in the range of 20 to 30 percent of compressor output, to be lost through leaks rather than reaching productive use. A structured survey, tag, and repair programme is the standard fix: leaks are located, tagged, estimated for flow, logged, and repaired largest-first, with the survey repeated quarterly to twice a year as new leaks develop. A disciplined programme typically holds leakage to a low single-digit or low double-digit share of output.
| Leak orifice diameter | Approximate air loss at 6 to 7 bar | Typical priority |
|---|---|---|
| 1 mm | Low, roughly a few L/s | Adds up across many leaks |
| 3 mm | Moderate, roughly tens of L/s | Worth prompt repair |
| 6 mm | High, over 100 L/s | High priority repair |
| 10 mm | Very high | Equivalent to extra compressor capacity |
Exact flow depends on line pressure and orifice shape, so treat this as an order-of-magnitude guide, not a substitute for a specific detector reading.
Logging leak tags and trending leak volume over successive surveys is exactly the kind of recurring maintenance loop a CMMS platform like Fabrico is built to support. Book a Fabrico demo to see how leak tags fit into a broader condition monitoring workflow.
Steam trap testing with an ultrasonic detector, often paired with a contact temperature probe, lets an inspector classify a trap as normal, failed open, or failed closed without opening it. A failed-open trap blows live steam continuously and produces a strong, steady signal, while a failed-closed trap produces little sound and runs cooler than expected upstream. A regular trap survey, at least annually, is standard practice and pairs with a wider steam and condensate return inspection programme. Vacuum leak detection works on the same principle in reverse, locating leaks in packaging lines and vacuum furnaces without a tracer gas, though a helium sniffer remains more sensitive for very fine leaks.
Detectors range from simple screening units to advanced models with signal processing, leak-rate calculators, and data logging. The availability of contact probes for solid-borne ultrasound (bearings, steam lines) versus airborne sensors (leaks, electrical faults) is a key selection point, and results depend heavily on operator technique, so training matters as much as specification. Surveys complement rather than replace other methods; a detector that flags an unusual bearing sound should trigger a proper vibration analysis, and following a recognized framework such as ISO 18436 condition monitoring certification guidance keeps inspection integrated with the reliability programme.
Yes. The technique listens above normal industrial noise, and the detector is highly directional at close range, so it works well on a loud production floor.
Most facilities run a full survey two to four times a year, since new leaks develop continuously from vibration and wear at fittings.
Detectors can estimate leak flow and cost from signal strength, distance, and line pressure, accurate enough for prioritizing repairs. A precise measurement needs the leak isolated and measured directly.
Yes, including steam trap testing, electrical corona and arcing, and early acoustic signs of bearing wear, often before those faults show up in vibration or infrared monitoring.
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