| As our country’s economic developing, the state of the growing importance of environmental protection, natural gas vehicles with good social and economic benefits of natural gas is becoming an important direction for use. "Natural Gas Utilization Policy" August 31,2007 issued by the National Development and Reform Commission, the clearly defined natural gas vehicles belonging to the "priority category" gas projects. National Clean Vehicle Action has CNG as the preferred alternative fuel vehicle.For this social situation, this paper proposed to design CNG cylinders NDT inspection system, the paper outlines the development status of nondestructive testing technology at home and abroad, and through a variety of detection technologies compare, and ultimately proposed an ultrasonic-based NDT inspection system. The system uses a longitudinal wave direct probe and transverse angle probe as the primary ultrasonic generating and receiving means, and for the acquisition of an ultrasonic signal, filtering and amplification proposed synchronization circuit, a transmitting circuit, a time base circuit, a reception amplifying circuit, display and alarm and power supply and other design-related hardware circuit. CNG cylinder correction and direct contact with non-destructive flaw detection by coupling agents, through collaboration with various hardware circuits together to complete the acquisition of the ultrasonic signal by reference to the relevant type A pulse reflection technique, the probe by the test block. The collected ultrasonic echo information into the DSP processing and analysis correlation and waveform processed into the LCD display, and the display shows the beginning of wave based on defects and bottom spread a wave echoes and secondary echo position, to determine the size of defects, and the approximate location of the defect characterization. This design has been basically completed and put into reality test, but there are still many shortcomings to be gradually improve later.
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