Question 1

Which gases can be detected?

Accepted Answer

All gases can be detected because the system detects the leak itself, not the gas. It works by capturing the acoustic emissions generated by turbulent flow at the leak point, which are independent of the gas type. As a result, it works with virtually any gas, provided there is a pressure difference between the inside and outside of the system. This includes both pressurized leaks and vacuum leaks, where air is drawn into the system.

Question 2

Ultrasound vs infrared detection: what’s the difference?

Accepted Answer

Ultrasound and infrared detection rely on fundamentally different physical principles and are suited to different types of problems. Ultrasound detection measures high-frequency acoustic emissions generated by phenomena such as gas leaks, cavitation, electrical discharges, mechanical wear. It detects the sound produced by the source, and does not require direct line of sight, as reflected sound can also be detected. Infrared detection, by contrast, visualizes electromagnetic radiation not visible to the naked eye. Thermal cameras estimate the temperature of a body. With OGI cameras, gas clouds based on their optical absorption properties in specific wavelength bands can be detected. It requires the target gas to be optically active in the infrared spectrum and depends on favorable environmental conditions such as background contrast, limited wind and direct line of sight. In practice, ultrasound is particularly effective for detecting pressurized leaks and early-stage failures, even in complex or noisy environments. Infrared is best suited for visualizing larger gas plumes of specific gases. These technologies are therefore complementary: ultrasound excels at early detection and localization of leaks, while infrared provides direct visualization of gas clouds when conditions allow.

Question 3

What are the limitations of ultrasound leak detection?

Accepted Answer

A pressure difference is required. Ultrasound detection relies on turbulent flow at the leak point. In practice, a pressure difference of around 50 mbar is typically needed for reliable detection, although leaks can sometimes be detected at only a few millibars if the leak rate is high enough. Very small leaks may not be detectable. If the leak rate is too low, the emitted signal can fall below the detection threshold. In practice, the typical detection limit in industrial environment is on the order of a few liters per hour, depending on the gas type, pressure, distance, and background noise. Strong nearby ultrasonic sources can mask weak leaks. Other emissions such as compressed air tools or electrical activity can make small leaks harder to isolate, especially when the leak signal is close to the detection limit. Detection range is limited by distance. As distance increases, the acoustic signal attenuates, reducing both detection sensitivity and localization accuracy. In practice, a typical working range is around 8 m, although larger leaks can sometimes be detected from 50 m away.

Question 4

How does an ultrasound camera detect leaks?

Accepted Answer

An ultrasound camera detects leaks by capturing the high-frequency acoustic emissions generated by turbulent gas flow at the leak point. Using a multi-microphone array, it analyzes phase differences between sensors to localize the sound source in space and reconstruct an acoustic image, which is overlaid onto a visual image for intuitive identification.

Question 5

Does the number of microphones matter in an ultrasound camera?

Accepted Answer

In an ultrasound camera, the number of microphones impacts the system’s ability to detect small leaks in noisy industrial environments. More microphones improve detection performance by increasing dynamic range. This helps separate weak sound sources from stronger ones that might otherwise mask them. In practice, while as few as four non-coplanar microphones are sufficient to localize a single sound source in space, larger arrays provide much higher robustness, sensitivity, and side-lobe suppression. This enables reliable detection of weak leaks, resolution of multiple sources, and stable performance even when stronger ultrasonic emissions are present nearby. However, overall performance depends not only on the number of microphones, but also on signal processing and imaging algorithms.

Question 6

What frequencies are used in ultrasound leak detection?

Accepted Answer

Pressurized leaks generate broadband acoustic emissions, ranging from audible frequencies (perceived as a hissing sound) up to ultrasonic frequencies, typically in the 40–50 kHz range. At lower frequencies, background machinery noise tends to dominate, reducing detection performance. In contrast, the 30–40 kHz range generally offers a more favorable signal-to-noise ratio, making it particularly effective for reliable leak detection in industrial environments.

Question 7

How accurate is ultrasound localization?

Accepted Answer

Ultrasound localization accuracy depends primarily on the imaging frequency (and corresponding wavelength) and the size of the sensor array. Higher frequencies and larger arrays enable finer angular resolution. In practice, typical localization accuracy is on the order of about 1°. At a distance of 5 m, this corresponds to a lateral accuracy of about 9 cm. At higher frequencies, the shorter wavelength improves angular resolution. For example, increasing frequency from 30 kHz to 50 kHz can reduce the localization angle to around 0.6°, corresponding to roughly 5 cm at 5 m. Actual performance depends on factors such as signal-to-noise ratio, array geometry, and processing, but these figures illustrate the typical order of magnitude achievable in industrial conditions.

How Distran detects and localizes gas leaks in real-time

Why do gas leaks produce ultrasounds?

How does ultrasound imaging work

Why Distran imaging performs in real industrial environments

Robust detection in noisy environments

Wide acoustic field of view

High-quality acoustic imaging

DeepRange: Extended sensitivity for detecting smaller leaks in noisy environments

From detection to quantification

Frequently Asked Questions