Application photo of leak detection in a facility with acoustic imaging

How Does Acoustic Imaging Work?

Mainstream leak detection practices are, unfortunately quite primitive. An age-old method is to listen for hissing sounds, which are virtually impossible to hear in many environments and to spray soapy water on the area of the suspected leak, which is messy and can create a possible slipping hazard.

The current go-to tool for finding compressor leaks is an ultrasonic acoustic detector - a portable electronic device that recognizes high frequency sounds associated with air leaks. Typical ultrasonic detectors help find leaks but they're time consuming to use and repair crews can generally only use them during planned downtime, when maintaining other critical machines might be a better use of their time. These units also require the operator to be located close to the equipment to find leaks, which makes it difficult to use in hard-to-reach areas such as ceilings or behind other equipment.

In addition to the time it takes to find leaks using either soapy water or ultrasonic detectors, there can be safety issues with finding leaks overhead or under equipment using these techniques. Climbing ladders or crawling around equipment can pose dangers.

FLUKE Acoustic Imagers are sound cameras that include an array of 64 micro-electronic surface mount microphones to capture sound waves emanating from an object.


Do I Need An Acoustic Imager?

With advanced electronics and software algorithms, sound signals are converted into an image and overlaid onto a visual image (SoundMap) on the 7-inch, 1280 x 800-pixel LCD touchscreen. Like thermal camera technology for heat, acoustic imaging accurately pinpoints the direction of sound waves in a wide range of frequencies such as those from compressed air system leaks or partial discharge. Compressor system leaks typically range from 30 to 60kHz and partial discharges (electrical leaks) typically range from 20 to 110 kHz.

The FLUKE ii900 enables...

  • Ease-of-use
  • Visual localisation of leaks
  • Quick detection from the distance
  • Time-saving benefits
  • Reliable operation in noisy environment
  • Improved process control, less recycling
  • Increased efficiency
  • Leak quantification
  • Easy documentation
  • Cost reduction


Example Industries Who Could Benefit From Acoustic Imaging


Detect and localise leaks in Natural Gas Storage Installations

Location: Natural gas storage facilities across EMEA

Natural Gas Storage Installations (NSGIs) are remote sites where large volumes of gas are stored. These facilities provide a back up gas reservoir to face consumption peaks due to seasonal variations, among other reasons. Uptime of NSGIs is critical and they need to be available 365 days a year. The maintenance team requires the ability to quickly and effectively scan large areas from a safe distance with the certainty of reliability and accuracy.

Natural Gas Acoustic Imaging Application:

  • Natural gas leak detection and location within the facility
  • Safe site inspection from facility's perimeter

Time savings: Greater than 80%

FLUKE asked a maintenance leader from a Natural Gas Storage Installation:

"Why did you choose the FLUKE ii900?"

"The FLUKE ii900 is a fantastic aid to emergency response, so the location of any significant gas leak can be quickly identified from a safe distance, allowing appropriate elements of equipment to be remotely isolated and ventilated from the control room if required.

After just a few tests, we found how reliable the FLUKE ii900 is and the versatile ways it can be used.";



Detect and localise leaks in brake systems - Rail Industry

To ensure safety on the tracks, the maintenance technicians pay special attention to the braking system. The centralised pneumatic brake system is used to keep pressure on the system continuously and to ensure the brake shoes remain open. As soon as the pressure drops, the brakes engage and start causing undesired friction on the axles. A tricky, tiny leak in the compressed air system can lead to system malfunctions, which activate the brakes. These errors must be corrected as soon as possible.

Location: Railways maintenance site in Germany

User/department: Service and maintenance technicians, maintenance-technical management, process and work preparations, wagon and locomotive maintenance

Rail Acoustic Imaging Application:

  • Locating leaks in brake systems
  • Valves in the ventilation system
  • Vehicle components such as sanding system, pantograph and lubrication of the wheels

Time savings: Greater than 80%

FLUKE asked a maintenance leader from a German railway operator:

"Why did you choose the FLUKE ii900?"

"This innovative technology has excited me from the moment I first heard about it! The imager was primarily purchased for troubleshooting the trains' pneumatics. We have already seen enormous time savings with complex leakages.

After just a few tests, we found how reliable the system is and the versatile ways it can be used.

We are very pleased to see the high level of acceptance amongst our service technicians–the FLUKE ii900 has immediately become a standard tool for us."


Detect and localise leaks in Cement Manufacturing

Cement manufacturing process involves several phases where the process temperature needs to reach up to 2000 °C. These high temperatures result in equipment deformation, making it very likely for leaks to appear in various locations. These leaks decrease process temperature, which in turn increase coal or gas consumption to compensate for the temperature drop.

Location: Maintenance of cement plants

User/department: Maintenance Managers and Energy Managers

Cement Manufacturing Acoustic Imaging Application:

  • Vacuum in calcination
  • Dust removal filters
  • Flange connections
  • Pneumatic actuators
  • Packaging process

FLUKE asked a maintenance leader from a cement factory:

"Why did you choose the FLUKE ii900?"

"We were already aware of the leaks in our process but because of the high temperature and distance, we were not able to locate them. The FLUKE ii900 helped us to easily pinpoint the leaks and visually see them.

Reporting is extremely important for us. Documenting the exact leak locations and the ability to calculate ROI easily helps us get approval for the required investments from our top management.

We already found over 100 leaks in our production facilities through our inspections with the FLUKE ii900. We can easily improve energy efficiency by just fixing those leaks."


▶ Detect and Localise Leaks in Tire Manufacturing

Nitrogen, steam and compressed air are widely used in the tire manufacturing process. In the curing phase, steam is used to implement 8 bar pressure to liquify rubber compounds - and nitrogen is used for applying 24 bar pressure to shape the tire. If predefined pressure cannot be applied, the tire cannot pass the quality checks and is separated as waste. Beside the production losses, recycling the waste tire is also another source of additional cost.

Location: Maintenance in tire manufacturing

User/department: Maintenance Managers and Energy Managers

Tire Manufacturing Acoustic Imaging Application:

  • Steam and nitrogen usage in curing process
  • Leaks in moulding machinery due to high temperatures

FLUKE asked a maintenance engineer from a tire manufacturing plant

"Why did you choose the FLUKE ii900?"

"We were looking for a tool to easily detect the leaks and visually see the location as this is a pain point for us. We are glad that Fluke came up with a solution, which is beyond our expectations.

Safety is our priority, we are working in harsh environments - steam and high pressure is being used in various sections.

Detecting the leaks easily and visually from the distance is a major advantage.

The FLUKE ii900 helped us perform preventive maintenance, we are able to reduce downtime by detecting the problems in advance."




Why use the FLUKE ii900 Sonic Industrial Imager?

  1. Reduce costs: Research has shown a plant with compressed air can waste up to 30% of its total compressed air production capacity through leaks. Find the leaks, reduce waste, save money.
  2. Build maintenance efficiency: Enable your maintenance team to easily standardise leak detection audits and fix leaks on the go, and simplify reporting leaks in your workflow system
  3. Eliminate more unplanned downtime: Unplanned downtime costs!
  4. Optimise asset performance: Build asset-specific historical data for preventive maintenance planning.
  5. Generate reports: Generate reports and analyse losses to meet ISO50001 energy management requirements.
  6. Improve safety around hazardous gases: Propane, methane, fuel, acetone, ethanol, and benzene are among the hazardous gases that can be found within commercial and residential areas. Leaks of some gases can result in an explosion. Quickly pinpoint invisible and difficult to-access leaks to improve safety.
  7. Safeguard production quality: A drop in system pressure can make air tools function less efficiently and adversely affect production quality. Leaks can cause system pressure drops and shorten the life of system equipment, including the compressor.
  8. CO2 emission estimator: With the new CO2 emission estimator (weight) feature, part of the FLUKE Online LeakQ reporting tool, you can quantify the impact of each individual and total number of leak(s).
  9. Quantify CO2 emissions impact: Quantify the environmental and financial value of compressed are leaks. Drastically reduce your energy use and carbon footprint which helps ensure cleaner air, water, and food for our generation and for generations yet to come.
  10. Helping you improve uptime, save energy costs, and reduce your carbon footprint: With FLUKE's Acoustic Imager Series, anyone can identify if and where a compressed air leak might exist, and what size the leak is.