Views: 4 Author: pqwt Publish Time: 2022-10-31 Origin: PQWT
In recent years, with the gradual development of China's urban water supply, the management level of urban water supply pipeline network has been greatly improved. However, it should be noted that no matter how advanced the management level is, water leakage in urban water supply pipe networks is inevitable. Leakage of urban water supply network will not only lead to significant increase in water production cost and unnecessary water supply, but also cause huge economic loss and even ground collapse and damage to urban housing foundation. Therefore, in order to reduce the cost of water supply and save water resources, it is necessary to analyze the leakage of urban water supply network and its causes, and to control the leakage by using effective pipe leakage detectors.
1.Acoustic sensor detection method
As the gas transmission pressure in the pipeline is very high, the fluid is ejected outward through cracks or corrosion holes to form a sound source, and then the sound source interacts with the pipeline and radiates energy outward to form sound waves, which is the phenomenon of pipeline leakage acoustic emission. Through the pipeline leak detector to these acoustic emission signals caused by the leak to collect and analyze the processing, it is possible to accurately determine the leak and its location.
2. Cable detection method
The leak detection cable method involves laying a special leak detection cable on the pipeline (which reacts with the gas leaking from the pipeline). When a leak occurs in the pipeline, the capacitance or resistance of the cable changes in nature and is converted into an electrical or optical signal output, and the occurrence of the leak and the location of the leak is detected by a special pipeline leak detector.
3. Pressure sensor detection method
When a leak occurs in a pipeline, the leak immediately produces a local reduction in fluid, which is caused by the loss of fluid material and transient pressure drop and velocity difference. This transient pressure drop, acting on the fluid medium, acts as the source of a pressure reduction wave that propagates through the pipeline and fluid medium upstream and downstream to the leak point at the speed of sound. When the pressure before the leak is used as a reference standard, the pressure-reducing wave generated by the leak is called a negative pressure wave. Negative pressure waves propagate and decay upstream and downstream, and this pressure fluctuation has an almost vertical leading edge. As shown in Figure 2, it is possible to determine whether a pipeline leak has occurred by monitoring pipeline pressure parameters and capturing sudden changes in instantaneous pressure through pressure sensors installed upstream and downstream of the pipeline. The time difference between the arrival of the negative pressure wave at the upstream and downstream measurement points of the pipeline is measured, and the location of the leak can be calculated based on the speed of the pressure wave propagation in the pipeline.
4. Ultrasonic detection method
When ultrasonic waves propagate in a medium such as a pipe, they are reflected back and forth at the interface, producing complex waveform transitions and mutual interference. This is guided by the medium boundary propagation of ultrasound waves become ultrasonic waveguide. In the pipeline ultrasonic waveguide detection, the sensor is an important part of the detection system. Choose different sensors to excite a single or different modes of waveguide for pipeline detection.
5. Leak detection method
Leak detection method uses the high magnetic permeability of ferromagnetic materials to detect leaks by measuring the change in magnetic permeability of ferromagnetic materials caused by pipe leaks. Pipeline leakage magnetization refers to the magnetization of the pipe wall and the detection of the magnitude of the leakage magnetic field at the pipe wall by a sensor to determine the location of the leakage in the pipe.