Abstract:

In the manufacture of devices that are to be filled with pressurized gases or liquids, efficient localization of leaks is a critical quality control process. Current assembly-line leak localization techniques such as bubble visualization, sniffing devices, or helium-mass spectrometers are either subjective or time consuming. Photoacoustics has already been used to detect small leaks but has not been extended to the localization of these leaks. This work presents a quick and objective leak localization method. Sulfur hexafluoride is used as the tracer gas. Photoacoustic sound is generated by rapidly scanning a carbon dioxide laser tuned to 10.6 (mu)m over a suspected leak area. The sound is measured by multiple microphones. Using the microphone output and signal processing techniques, the location of the leak is determined. Leak location uncertainty due to microphone placement, laser scanning, and leak size is discussed. A signal-to-noise-ratio-dependent leak detection limit is established. Experimental results are presented. [Work supported by Ford Motor Company.]