Microphone Arrays as a Leakage Detection Tool in Industrial Compressed Air Systems

Abstract

Compressed air energy is expensive, but common in industrial manufacturing plant. However, a significant part of the generated compressed air energy is lost due to leakage. Best practice requires ongoing leak detection and repair. Leak detection in the ultrasonic frequency range using handheld devices is possible only over short distances as associated high-frequency sound is rapidly attenuated by atmospheric absorption. Pressurized air escaping to ambience also generates frequencies below 20 kHz. In this paper beamforming—a well known method for generating noise maps—is tested as a tool for localization of compressed air leaks at larger distances in the audible frequency range. Advanced beamforming methods in both time domain (broadband) and frequency domain (narrowband) have been implemented in a variety of situations on a laboratory experimental rig with several open blows representing leakage in a noisy environment similar to a factory setting. Based on the results achieved it is concluded that the microphone array approach has the potential to be a robust leak identification tool. The experience gained here can also provide useful guidance to the practitioner.

Quantifying Compressed Air Leakage through Non-Intrusive Load Monitoring Techniques in the Context of Energy Audits

“…The hardware techniques use numerous equipment to enhance the sensorial perception of the staff. In the case of compressed air systems, the most used are ultrasound [8,9] devices and infrared cameras [7]. Although it is considered the industry standard and best practice, ultrasonic leak detection is limited to the application in short distances [10] and requires highly trained operators.…”

“…There are several techniques to detect and quantify the leakage in compressed air systems. Among them is the use of ultrasonic detectors [8,9] and infrared cameras [7,8]. Although these methods are the industry standard to locate the leaks, they are impractical [10] for the leakage quantification, particularly in the context of an energy audit.…”

Aeroacoustic Source Separation on a Full Scale Nose Landing Gear Featuring Combinations of Low Noise Technologies

“…Although the technique cannot be applied to correlated sources, it suits well the separation of the broadband signals [10]. When applied to the individual and combined low noise technologies the process can reveal additional sources beyond the dominant noise source in the frequency range of interest.…”

Characterization of Low Noise Technologies Applied to a Full Scale Fuselage Mounted Nose Landing Gear

“…The procedure is shown in Figure 8. Although the technique cannot be applied to correlated sources, it suits well the separation of the broadband signals [10]. When applied to the individual and combined low noise technologies the process can reveal additional sources beyond the dominant noise source in the frequency range of interest.…”