Listening to High-Frequency Acoustics from Gas Leaks with an Optical Microphone
* Presenting author
Leaks emitting inflammable gases can severely compromise the safety of personnel and infrastructure in gas industry facilities. Today, airborne ultrasound is commonly used to detect, localize and quantify gas leaks. However, attenuation and possible obstructions in the sound path require operation of the sensors within the explosive hazard zone to be effective. While handheld acoustic leak detectors for hazard areas exist, there is a lack of ATEX/Ex-certified ultrasound sensors suitable for fixed installation.We present an all-optical microphone well-suited for detecting and quantifying gas leaks in explosive atmospheres. The small, fiber-coupled sensor head is based on a miniaturized laser interferometer and can detect air-borne sound at frequencies ranging from 10 Hz up to 1 MHz. Results from two test campaigns at the TADI (Transverse Anomaly Detection Infrastructure) test site established by TOTAL are presented. The project’s aim is to develop a comprehensive leak detection and quantification system by combining data from various sensing technologies. It was found that for realistic leak parameters, airborne acoustic emission up to 350 kHz is observed, and the assessment of those high frequencies can strongly boost the reliability of quantification algorithms. An outlook on analysis techniques making use of the optical microphone’s features is presented.