---
title: How to Find Compressed Air Leaks With Ultrasound and Get Them Fixed
slug: find-compressed-air-leaks
url: /topics/cartoons/find-compressed-air-leaks/index.md
publishedAt: "2026-11-07T13:45:45"
updatedAt: "2026-11-07T13:45:45"
excerpt: "One of the costliest losses on a plant floor is one nobody can hear. Air escaping through a worn quick-connect makes a hiss that vanishes under production noise, while the compressor in the next room runs harder to keep up. Knowing how to find compressed air leaks is the first half of the fix. The […]"
authors:
  - Reliable Media
  - Alison Field
---

# How to Find Compressed Air Leaks With Ultrasound and Get Them Fixed

By [Reliable Media](/authors/reliable-media/index.md), [Alison Field](/authors/alison-field/index.md)

One of the costliest losses on a plant floor is one nobody can hear. Air escaping through a worn quick-connect makes a hiss that vanishes under production noise, while the compressor in the next room runs harder to keep up.

Knowing how to find compressed air leaks is the first half of the fix. The second half, getting leaks repaired and keeping them repaired, is where a lot of leak programs stall.

This guide covers both halves: how ultrasonic detection works, how to measure the leak load, how to run a survey, and how to turn a pile of leak tags into finished repairs.

## What Compressed Air Leaks Really Cost

Compressed air ranks among the most expensive utilities in a plant. Commonly cited estimates put the overall efficiency of a compressed air system at roughly 10 to 15 percent, which means the bulk of the electricity a compressor draws ends up as heat.

The math on a single leak is sobering. At 100 psig, a hole an eighth of an inch across can pass roughly 25 cfm. Assuming about 18 kW of compressor power per 100 cfm, replacing that air takes around 4.5 kW around the clock, or close to $4,000 a year at $0.10 per kWh. Actual power savings depend on how the compressors respond to the lower demand.

> A leak keeps running nights, weekends, and holidays, as long as the header stays pressurized.

Multiply that across a plant. U.S. Department of Energy guidance has long put leak losses in a poorly maintained system at 20 to 30 percent of total compressor output, while a well-run system can hold leaks under 10 percent.

The energy is only part of the damage. Leaks drag down system pressure, which tempts someone to raise the setpoint, which makes each leak worse. They also add run hours to compressors and can push a plant toward buying capacity it shouldn't need.

Low pressure at the point of use hurts production, too. Pneumatic tools lose torque, cylinders cycle slower, and air-operated valves get sluggish. Those symptoms tend to show up as quality and throughput complaints long before anyone suspects the air system.

Leaks also hide inside the accounting. Plants that meter electricity by building often can't see the air system's share of energy spend, so the loss rides along unnoticed in overall utility costs.

## How to Find Compressed Air Leaks With Ultrasound

Learning how to find compressed air leaks starts with understanding what the detector hears. Air forced through a small opening creates turbulence, and turbulence produces ultrasound above the roughly 20 kHz limit of human hearing.

An ultrasonic leak detector picks up that high-frequency sound, typically around 40 kHz, and translates it down into the audible range through headphones. Because the instrument listens in a narrow ultrasonic band, it filters out much of the low-frequency plant noise that masks a leak to the ear.

Directional sensitivity does the rest. A technician sweeps the scanning module across fittings and hoses, follows the signal as it strengthens, then switches to a rubber focusing cone or close-focus probe to pinpoint the exact spot.

When finding compressed air leaks in a crowded area, start with the sensitivity turned up to locate the general zone, then turn it down as you close in. As the gain drops, the strongest signal narrows to the actual leak point.

Reflections can mislead. Ultrasound bounces off hard surfaces like sheet metal and concrete, so a signal that seems to come from a panel may be a leak on the fitting beside it. Approach from a second angle before hanging a tag.

Soapy water still has a place. For a suspected leak on a fitting within easy reach, a spray bottle confirms the spot in seconds, and the speed of the bubbles gives a rough sense of size.

Acoustic imaging cameras speed up surveys of overhead piping and crowded panels by showing leak locations on a screen. A standard handheld detector still finds plenty of leaks at a fraction of the price, and many programs start there.

If the plant is still working out [how to start a condition monitoring program](/topics/cartoons/start-condition-monitoring-program), an airborne ultrasound leak route makes a practical first step. The same instrument can later listen to bearings, steam traps, and electrical gear.

## Measure the Leak Load Before You Survey

Before tagging anything, establish how much air the system loses. That baseline sizes the opportunity and gives the program something to measure progress against.

For load/unload compressors, the simplest method is to run during a period with no production demand. Bring the system to pressure, then time several loaded and unloaded cycles. Leakage as a percentage of compressor capacity equals loaded time divided by total cycle time, multiplied by 100.

> With intentional air uses shut off or accounted for, the air a plant consumes while production sits idle is the leak load.

Systems with modulating or variable-speed compressors need a different approach. A pressure decay test works here: isolate the supply, time how long the system takes to fall from operating pressure to a lower set point, and calculate leakage from the total system volume.

A flow meter on the main header gives the cleanest answer of all, and some systems already have one feeding the plant historian. If yours does, trend the weekend baseline flow. It works as a running leak gauge at no extra cost.

Record the result as both cfm and dollars per year. Technicians think in cfm, plant managers think in dollars, and the program needs support from both.

## Where Compressed Air Leaks Hide

Leaks cluster at connections and anywhere a component flexes, vibrates, or gets handled. Start at the points of use, where fittings connect and disconnect daily, and work back toward the compressor room. Common sources include:

* Quick-disconnect couplings and push-to-connect fittings
* Hoses, tubing, and the clamps that hold them
* Filters, regulators, and lubricators at machine drops
* Condensate drains and traps, especially ones left cracked open.
* Threaded pipe joints, unions, and flanges
* Pneumatic cylinder rod seals and solenoid valve exhausts

Condensate drains deserve a close look. A drain valve left cracked open to keep water out of the line acts as a deliberate leak, and electronic or zero-loss drains often pay for themselves quickly.

Check idle and abandoned equipment, too. A machine taken out of service often keeps its air drop pressurized, leaking for months until someone closes the isolation valve.

Open blow-off lines used for cooling or cleaning, cabinet coolers left running, and air lances without a shutoff all waste air whenever nobody is using them. Log them in the survey as inappropriate uses so they get their own fix, such as a timer, a solenoid valve, or an engineered nozzle.

## Run the Leak Survey Like a Route

Split the plant into zones and survey one zone per session. A focused two-hour pass through a single area catches more than a rushed walk through the whole building, since fatigue sets in and small leaks get skipped.

Timing matters. Ultrasonic detectors cope well with production noise, but a weekend or shutdown shift makes small leaks easier to isolate and lets technicians reach equipment that's normally guarded or running.

> A quiet shift with full access finds the leaks a busy shift walks past.

Tag each leak the moment it's found. A durable tag with a number, the date, and a size estimate hangs at the leak, and the same details go into a survey log with a clear location note.

Once the affected section is safely isolated and depressurized, fix what you can on the spot. Tightening a fitting, replacing an O-ring, or swapping a worn quick-connect takes minutes. A technician carrying a small kit of common fittings and thread sealant can close a good share of leaks during the survey itself.

Repeat the survey on a schedule. Quarterly suits many plants, and high-turnover areas with lots of hoses and quick-connects may need a monthly pass.

## Rank and Repair the Rest

Leaks that need additional parts or a scheduled isolation or shutdown become work orders, and that handoff is where programs lose momentum. A list of 140 tags with no owner and no due date tends to sit until the tags fade. Rank the open leaks by:

* Estimated leak rate, so the biggest losses go first
* Ease of repair, since quick wins build momentum
* Isolation needs, grouping shutdown-dependent jobs into the next planned window.
* Safety, moving leaks near personnel or controls up the list

Write each large leak as its own work order, or bundle a zone's smaller leaks into one job with a checklist. Either way, track repair status so the survey log shows open and closed tags, and so the next survey can confirm the fixes held.

Report progress the same way each month: leaks found, leaks fixed, estimated cfm recovered, and dollars saved. Teams that know how to find compressed air leaks but skip the reporting tend to lose program funding right when the savings start to show.

Price the backlog in dollars. Multiplying each leak's estimated cfm by the plant's cost per cfm-year turns a list of tags into a number that gets attention in a planning meeting.

Give the repair list an owner. A single planner or area supervisor who reviews open leak tags weekly keeps the backlog moving, and a target repair window (two weeks for large leaks, say) gives that owner something to manage against.

Verify each repair with the detector before closing the work order. A fitting that got re-taped can start leaking from the next thread, and a quick scan takes seconds.

## Keep Compressed Air Leaks From Coming Back

Leak repairs decay. Fittings loosen, hoses age, and new equipment arrives with its own connections. Without a sustaining effort, leak load tends to creep back toward its starting point.

Lower the system pressure where possible. Leak flow rises with pressure, so a header running at 110 psig to serve one demanding tool wastes air at each leak in the plant. A dedicated booster for that tool lets the rest of the system run lower.

> Each psi of unnecessary header pressure feeds the leaks across the whole plant.

Treat compressed air as part of [energy asset management](/topics/articles/strategic-asset-management-energy-efficiency). Trend the weekend baseline flow, report leak load monthly, and hold the program to a target, such as leaks under 10 percent of compressor output.

Where the plant runs reciprocating units, solid [reciprocating compressor maintenance](/topics/articles/reciprocating-compressor-maintenance) keeps the supply side efficient. Even a well-maintained compressor wastes money feeding leaks downstream, so the leak route and the compressor PMs belong in the same plan.

Bring operators into it. They walk the same lines each shift and hear the big leaks first. A simple way to report one- a tag on the machine or a quick CMMS entry- adds dozens of listeners between formal compressed air leak surveys.

The payoff for learning how to find compressed air leaks shows up fast. Plants can recover the cost of a detector and the survey labor within the first few months, and the savings continue as long as the route keeps running.