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To meet the needs of on-site fault diagnosis for hydraulic equipment, many specialized hydraulic fault diagnostic instruments have been developed both domestically and internationally in recent years.
Pressure diagnostic instruments. The rapid development of pressure sensors has greatly promoted the development of pressure diagnostic instruments. Domestically, Zhejiang University has developed a fluid pressure waveform acquisition instrument, which can be carried by maintenance personnel to the site for testing, recording, and displaying the system’s pressure values and pressure waveforms for analysis and diagnosis of system faults. This instrument is compact, lightweight, and easy to carry; powered by batteries, it can work continuously for more than 5 hours; measurement accuracy reaches 20/00, with a frequency response of AC 350Hz.
Internationally, there are specialized instruments produced by Denison Hydraulic Company in the USA, which combine LPT pressure sensors with DP110 indicators for easy operation and accurate testing, widely used in hydraulic test benches, machine tool equipment, and other fluid transmission and control engineering fields. The pressure measurement range of this instrument is 1~40 MPa, with an error of less than 5‰, and the output signal is 0~10V or 10mA.
Flow diagnostic instruments. Ultrasonic flowmeters, developed based on ultrasonic principles, can conveniently be used for on-site fault diagnosis of hydraulic systems. Ultrasonic flowmeters are classified into insertion and non-insertion types based on whether their sensors contact the measured medium. Insertion types require a pre-drilled hole in the pipeline at the measurement point, while non-insertion types do not require pre-drilling; their sensors are uniquely clamped to the outer wall of the pipeline, making on-site testing more convenient. Domestically, there are options available such as the MTPCL series flowmeter developed by Tailong Measurement and Control Industry Group. Internationally, there are many such flowmeters, including the UF series flowmeters from KROHNE in Germany, the 190 series from Contrlotron in the USA, and the DDF series from Polysonies in the USA; the characteristic of non-insertion ultrasonic flowmeters is that they can easily achieve continuous flow access, enabling online detection, though these instruments tend to be more expensive.
Note: Please contact the author for authorization to reprint. Author: Professor Huang Zhijian, Guangzhou New Europe Machinery Co., Ltd., 020-82333916
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