Testing technology for Underwater leak test, also automatic with ultrasound

The underwater leak test is a method for leak testing and leak detection on medium and large components, in which a test item subjected to compressed air is lowered into a water bath. Rising air bubbles can be visually detected by the operator or automatically located with ultrasonic sensors. The test system includes compressed air connections, semi-automatic or fully automatic handling for lowering and lifting workpieces, a water basin and, if necessary, water treatment. In the automatic gas bubble detection method, the ultrasonic sensor system and a control and evaluation unit are added. Leak rates of up to approx. 10-4 mbar l / s can be detected in visual control processes. Test items are casting parts such as gearbox housings and covers, coupling housings and crankcases. Disadvantages of this method are the subjective assessment of the leak rate and the possible visual impairment due to contamination in the water, which often requires a lot of effort in water treatment. The automated ultrasonic method with gas bubble detection enables the detection of practical leak rates of up to 10-5 mbar l / s with ultrasonic sensors. Ultrasonic waves are reflected and scattered back when they hit air bubbles in the water. Air bubbles can be localized by evaluating the sound propagation time and thus leaks localized reliably and reproducibly. The ultrasonic procedure is autonomous of soiling in a water bath. It is suitable for petrol and oil-tight components such as fuel tanks, fuel lines, fuel rail and oil pans and stainless steel fittings, radiators and gas cylinders. Typical user sectors are the automotive and automotive supply industry, foundries as well as valve and tank builders. Leak localization is required if defective workpieces are to be reworked due to their high value and not disposed of as scrap. Another field of application is the weak point analysis of components and manufacturing processes.