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Leak testing of truck brake systems another use for

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Leak Testing of Truck Brake Systems Another use for the ultrasound detector is inspecting truck air brake systems to locate the leak or source of internal air bypassing that would not be indicated on the system air gage but could be in violation of governmental regulations. The air brake system of a large truck can be checked for both internal and external leaks in 10 to 15 min. Because the system requires no further analysis than the judgment and experience of qualified inspectors, who can recognize the sound of a leak or a valve that is not shutting sufficiently, training for detector use takes only a short time. In one truck repair station, some 40 mechanics and lubrication personnel are adept in ultrasound testing of air brake systems. To inspect an air brake system, the unit’s pressure is built up and the brakes are applied to check storage and application pressure at the same time. With the ultrasound detector, the inspectors scan the brake system’s tubing valves and fittings from underneath (either by creeper or at the grease pit). A leak will produce a pronounced hissing. An instance of valve malfunction will produce a flowing sound where there should be silence. Inspection includes the entire course of tubing, hose, fittings, tanks and valves. When the instrument emits a hissing sound, the probe is zeroed on the precise location and the fault is marked for repair or replacement or, if possible, corrected at that time. Similar test techniques are used on refrigerated trucks, especially on the flexible tubing and fittings beneath the trailer. The device also is used to check for and locate fuel system leaks. Fuel Injector Performance Testing As fuel injectors become dirty or worn, the spray pattern will change and the fuel will not be atomized properly. With an unobstructed nozzle, the fuel will be atomized into a very fine particle size. This optimizes the combustion 209 Acoustic Leak Testing
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process and provides maximum fuel economy. If the contact probe is placed on the fuel injector body or on the fuel inlet line to the injector, ultrasonic readings can be taken and comparisons made. The good injector spray pattern will produce a more turbulent flow and will have higher amplitude. The poor spray pattern will have a lower amplitude because the turbulent flow is less. These tests can be performed while the engine is in operation, which can save many work hours. 210 Acoustic Emission Testing
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Locating Leaks in Evacuated Systems An ultrasound detection unit has proved a valuable supplement to the mass spectrometer for inspecting the integrity of vacuum enclosures and locating gross leaks in high power electron tube water cooling circuits. In this application, ultrasound detection provides a fast means for locating leaks on the order of 0.1 mm (0.004 in.) in diameter. These have leakage rates large enough to saturate the mass spectrometer leak detector. This example demonstrates the leakage range where each leak test technique is best used. Ultrasound detectors are used to locate big leaks.
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  • Fall '19
  • Acoustic Emission

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