What is Acoustic Imaging? What is an Acoustic Imager?

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What is Acoustic Imaging? How does an Acoustic Imager work?

What is Acoustic Imaging? What is an Acoustic Imager?

Acoustic Imaging helps us “see” sound by displaying the sound source in the form of an image. It displays the sound location as a spatial distribution of cloud, portraying it as an ultrasonographic space sound field distribution. The colour and brightness of the image represents the strength of the sound.

An Acoustic Imager measures the amplitude of the sound waves emitted from a sound source, by using complex, modern and sensitive, phased microphone arrays. It measures the phase and time difference of multiple sound waves from the source location (how long they take to reach the imager microphones).

Acoustic imaging detection equipment is an important supplement or even a addition for traditional gas leakage detection methods, and is a necessary tool for intelligent and efficient operations.

Principle of Acoustic Imaging and Application Value of Gas Leakage Detection

When pressurised gas leaks, it travels from the high pressure side to the low pressure side. In the process of the gas flow, a vortex forms and it develops and breaks continuously, radiating ultrasonic energy outwards.
An Acoustic Imager images the sound source in the ultrasonic frequency band and the displays results as imagery to show whether there is a gas leak and its location.

Gas leakage from all holes, small cracks, etc., will produce acoustic energy (including ultrasonic frequency band).

The ultrasonic imaging principle enhances detection sensitivity. Based on the sensor array technology and a beam-forming algorithm, It greatly improves the detection sensitivity and anti-noise ability. It helps detect even the faintest of gas leaks.
The sound source data formed by the leak is combined with the video pictures to produce a real-time video stream, which makes you “see the leak” and quickly lock into the source of the leak.
The testing distance can be as close as 0.5 meters and from upto 50 meters; making it very convenient for detection. Alongvwith being a much flexible detection method, it also can adapt to various detection positions and hence, avoids blind spots.

How Acoustic Imaging Works

The Metravi Pro AI-09 Acoustic Imager is an essential tool for predictive and preventive maintenance processes. It helps industries reduce losses caused due to gas leakage, partial discharge and other accidents. It shows you the exact location of leaks and the software tells you how much they cost annually, assisting you in keeping energy expenditures and hence, production costs low.
Compared to traditional ultrasonic leak detectors and other conventional methods, the Metravi Acoustic Imager is considerably more accurate and improves energy efficiency.



The external supply of civil natural gas at a natural gas supply base has the pipeline and valve in the station relatively concentrated. A 15-minute inspection using the Metravi Pro Acoustic Imager revealed multiple leaks.
0.6~2Mpa Natural Gas
0.2~ 0.4Mpa Nitrogen

Natural Gas Leakage Detection
Nitrogen Gas Leakage Detection


Pure nitrogen of 0.2MPa is used as protective gas in the workshop for preparing pharmaceutical intermediates.The Metravi Pro Acoustic Imager was used to inspect the pipeline in the workshop, and it was found that there was leakage in one flange weld and one pipeline valve.
Both leakage quantities were relatively small, which had not been found by the workshop manager before the test.
Gas type:99.99% Pure Nitrogen (medical)
Gas pressure: 0.2MPa

Pure Nitrogen Leakage Detection


A thermal power plant uses coal as energy and supplies a large amount of compressed air and steam at high temperature and high pressure. Equipment and pipes are all over the plant.
The Metravi Acoustic Imager helped find a large number of leakage points during the inspection of equipment and pipes in the park.
Type: High temperature and high pressure steam/compressed air

Steam Leakage Detection
Compressed Air Leakage Detection


There are a wide variety of gases in chemical plants. In addition to conventional compressed air, there are a variety of raw material gases and product gases. Inspectors equipped with soapy water and flammable gas detectorS cannot cope with such a wide variety of gas types and often miss detection and it is easy to miss safety risks.
The Metravi Pro Acoustic Imager is used for rapid detection and checking of various sealing points. The Imager easily detected leakage points of various gas types, including compressed air, hydrogen, nitrogen, ammonia, natural gas, etc.
Gas types: Natural Gas, Ammonia, Hydrogen, Nitrogen Gas
Pressure: 0.2~10MPa

Detecting Compressed Gas, Mixture of Hydrogen & Nitrogen Gases, Natural Gas and Ammonia (respectively)

Acoustic Imaging Applications

  • PETROCHEMICAL INDUSTRY (All kinds of Petrochemical Enterprises and other Chemical Enterprises): Test leakages for all kinds of product and process gases.
  • NATURAL GAS INDUSTRY (Natural Gas Transmission Company, Natural Gas Field Station, Gate Station, Users): Test for leakage natural gas and nitrogen.
  • MANUFACTURING INDUSTRY (Automobile Manufacturing and Machinery Manufacturing): Test leakage for all kinds of power and process gases, sealing detection of air, hydrogen, nitrogen, flammable gases.
  • METALLURGICAL INDUSTRY (Steel, Non-ferrous Metals, Metal Powder Enterprises): Detect leakage of air, nitrogen, oxygen, carbon dioxide.
  • POWER GENERATION INDUSTRY (Thermal Power Plants, Hydroelectric Power Plants, Gas Turbine Power Plants, New Energy Power Plants): Detect steam, air, hydrogen, ammonia leakages.
  • FOOD & BEVERAGES INDUSTRY: Test air, nitrogen, ammonia, oxygen, carbon dioxide and other gas leakages.
  • RAILWAYS & TRANSPORT (Vehicle Manufacturing, Use Maintenance): Detect the air used for braking, vehicle sealing test.
  • CEMENT INDUSTRY (Cement Factory): Test leakages for CO2,SO2,CO,NOx, air.
  • OTHER INDUSTRIES (Pharmaceutical, Hospital, Packaging, Aerospace, Textile, Rubber, Wind Turbine Blade, Production Plants): Detect oxygen, nitrogen, air leakages.
  • ELECTRICAL (Localisation of abnormal circuit noise): Detect abnormal circuit noise and vibration noise caused by capacitor, inductor and transformer damage during circuit operations.
  • VEHICLE MAINTENANCE (Abnormal sound from car): The sounds generated by the irregular vibration of the car’s
    internal components can be visually displayed by the imager to find and locate the problem fast.
  • PARTIAL DISCHARGE DETECTION: Non-contact testing ensures the safety while testing live circuits. Metravi Pro Acoustic Imager provides three test results for local discharges: intensity estimation, audio-visual cloud image and local discharge map – and all three help to quickly detect and evaluate the local discharge status.

Stay tuned for next article on Metravi Pro AI-09 Acoustic Imager Partial Discharge Applications…

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