Views: 10 Author: pqwt Publish Time: 2022-05-17 Origin: pqwt
Water supply network under certain pressure, once the breakage occurs leakage, due to the role of the difference in atmospheric pressure inside and outside the pipe, water will escape from the breakage point, and has a certain speed, the escaped water will produce two mechanical movement process.
Due to the viscous nature of water and has the initial velocity, will rub the pipe wall, the formation of vibration, the vibration in the form of fluctuations in the breakage along the pipe to both sides of the propagation.
In terms of fluctuation theory, the fluctuations belong to the line wave, the source of sound for the leak point, sound energy - sound intensity is exponential law decay, the attenuation coefficient and the propagation medium modulus of elasticity, the size of the water pressure, the frequency of sound waves.
Leakage sound waves in the process of propagation (here mainly discusses the direction of propagation along the pipe, in the soil to radial propagation also follows this rule) due to media loss, the wave energy of different frequencies will appear attenuation, high-frequency attenuation faster, low-frequency attenuation slower: the closer to the leak point, the closer to the pipeline, the more the sound energy - sound intensity is exponential law decay.
The closer to the leak point, the higher the relative proportion of high-frequency part of the energy of the pipe leak detector, through a certain pipe leak detector with the ears, will feel the sound sharp; the farther away from the leak point, due to high-frequency attenuation faster, so the human ear will feel the sound more subdued.
Come to understand the current most important valve bolt listening and road listening to find the working principle of underground pipeline leaks.
Valve bolt listening principle
When the water column escapes from the breakage, because of the quality and initial velocity, will impact the soil medium around the pipe body, the formation of vibration, and in the form of fluctuations, in the form of spherical dispersion around the propagation.
Its fluctuations belong to the spherical wave, its attenuation consists of two parts: the spatial direction propagation of the spherical dispersion and radial direction propagation of the internal medium heat loss, radial propagation follows the attenuation law of the line wave.
It is easy to know that the closer the distance of water leakage noise propagation propagation, the greater the sound intensity at the location, the detection of water leakage sound waves along the pipeline at ground level, due to the distance relative to any beveled edge to take the minimum value, so there is a maximum sound intensity near the point of leakage ground projection point. Using this feature, you can use the pipe leak detector ground listening sound way for accurate pre-location of the leak point.
Working principle of road surface listening
The spectral characteristics of water leakage sound waves are obvious, and the frequency band distribution of water leakage sound waves is generally between 0Hz-5000Hz.
Due to the propagation process, the vibration caused by the medium's internal heat loss and other special structure (three-way, four-way, cavity, etc.) causes energy attenuation, high-frequency attenuation fast, low-frequency attenuation slow.
The closer to the leakage point, the higher frequency part of the energy is relatively concentrated, the sound is sharp; the farther away from the leakage point, because the high frequency part of the attenuation is faster, the low frequency part of the energy is relatively concentrated, the sound is low.
PQWT Pipe leak detector product recommendation