JPS623659A - Ultrasonic gas pipe water pipe discriminator - Google Patents

Abstract

PURPOSE:To execute safely a construction work by using the fact that the attenuation factor of an ultrasonic wave is different by the classification of a medium when the ultrasonic wave transmits the medium and discriminating a fluid in a pipe to be examined to discriminate the calssification of this pipe. CONSTITUTION:A probe 1 is connected to a fluid discriminator body 5 through a lead wire 4 after being fixed to the surface of a pipe 2 to be examined exposed on the ground with a coupling paste 3. The body 5 is so constituted that it can be carried, and a start switch 6 operated from the probe 1 and a tube diameter selecting switch 7 which is used to set the diameter of the pipe 2 to be examined before the switch 6 is turned on are provided on the panel face. A gas pipe indicator lamp 9 which is lit when a fluid 8 passing the pipe 2o to be examined is discriminated as gas and a water pipe indicator lamp 10 which is lit when the fluid 8 is discriminated as water are attached to the panel face. The fluid 8 is discriminated as gas or water in accordance with the reception level of the probe 1, and the pipe 2 to be examined is discriminated as a water pipe or a gas pipe to display the discrimination result on indicator lamps 9 and 10.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention identifies whether the fluid inside the pipe is water or gas, for example, when a part of the underground pipe is exposed during various construction works. This invention relates to an ultrasonic gas/water pipe discriminator for safely carrying out construction work by determining whether exposed pipes are gas pipes or water pipes.

(Prior art) Conventionally, among the pillar pipes buried underground, water pipes and gas pipes have similar diameters and materials, but are often buried adjacent to each other. When exposing pipes and replacing them or connecting them, experienced workers had to identify each pipe by intuition, or excavate to the joints and distinguish them by the shape of the joints. This could lead to misjudgment, leading to the possibility of opening a pipe that was not intended for the purpose of construction, which could lead to a serious accident.

(Problems to be Solved by the Invention) The present invention aims to solve the technical problem of identifying the type of fluid in a pipe by using ultrasonic waves, which have a simple structure and are inexpensive.

(Means for solving the problem) The technical means for solving the above problem is that an ultrasonic gas water pipe discriminator is attached to the surface of the pipe to be inspected that conducts fluid, and emits ultrasonic waves. , a probe that receives the ultrasonic waves reflected on the inner surface of the probe tube after the emitted ultrasonic waves have passed through the fluid as a main medium and outputs an electric signal corresponding to the reception level; and from the probe. In addition to supplying transmission power to the probe to transmit impulse-like ultrasonic waves, the electric signal output from the probe is inputted at a reception timing set according to the diameter of the pipe to be probed. ,
The present invention includes a fluid identification circuit that identifies and displays whether the fluid is water or gas based on the attenuation rate corresponding to the electrical signal.

(Function) Ultrasound is a sound wave and exhibits properties similar to those of sound waves, but as the frequency increases, its directivity improves and it begins to exhibit properties similar to light. Among several properties of ultrasonic waves, two that are particularly relevant to the present invention are sound speed and specific acoustic impedance. The speed C at which an ultrasound wave passes through a medium depends on the modulus of elasticity of the medium and its gradation ρ. In the case of gases and liquids, k is the bulk modulus, and in the case of solids, it is the Young's modulus, and the relationship therebetween is expressed as CccJEf...■. Also, the actual speed of sound is 330 in air at room temperature.
7IL/S, about 1500 r'rL/s in water, and about 6400 m/s in steel, which vary greatly depending on the medium.

Next is the characteristic acoustic impedance Z, which is also called acoustic resistance and is expressed as the product of the wave propagation velocity C and the density ρ of the medium.

Z-ρC゛...■ This specific acoustic impedance Z has a large effect on the reflectance and transmittance of ultrasonic waves when they are reflected or transmitted at the interface between different media.

As shown in FIG. 1, different media 1. When an ultrasonic wave with a sound pressure level li is applied from a media engineer perpendicularly to the boundary surface of I[, a part of Lt is transmitted to the medium ■, and the rest is reflected at the boundary surface as lr, but the reflectance r is It is expressed by the following formula.

Incidentally, the specific acoustic impedance of a specific medium is as follows. However, pa is Pascal.

Steel 4.53 x 10” Pa -SEC/m
Water 0.143X 10" Air 0.0O004X 105 Utilizing the above-mentioned properties, when the probe 1 is attached to the excavated exposed pipe and transmits ultrasonic waves, the reflection shown in Figure 2 will occur. For example, when gas is present in the tube and when water is present, the transmitted wave Lt that passes through the tube
l and on the same plane as probe 1! 8 penetrating reflected waves] -t2
The sound pressure levels of will obviously differ. Port 1 and Lt2 are almost the same if the type of internal fluid is the same, and when you calculate the value, the attenuation rate of the sound pressure level when water exists inside is -23 dB, which means that there is gas inside. In this case, the attenuation rate of the sound pressure level is -93 dB. That is, when gas exists inside, the attenuation rate is large, and both the transmitted wave and the reflected wave have a property of being below the detection level.

Therefore, the fluid identification circuit can determine the degree of attenuation of the transmitted ultrasonic wave based on the intensity of the ultrasonic wave received by the probe 1, and can therefore determine whether the fluid as a medium is water or gas. .

(Example) Next, an example of the present invention will be described in detail with reference to the drawings. As shown in FIG. 3, an ultrasonic gaseous water pipe discriminator according to an embodiment of the present invention has a probe 1 formed of, for example, a ceramic piezoelectric element, which is exposed from a state buried underground. It is fixed to the surface of the inspected tube 2 using a coupling paste 3, and is connected to the fluid discriminator main body 5 via a lead wire 4. The fluid discriminator main body 5 is configured to be portable, and the panel surface is provided with, for example, several H
A start switch 6 for transmitting IIZ ultrasonic waves in the form of impulses, a pipe diameter selection switch 7 for setting the pipe diameter of the pipe to be investigated 2 before turning on the star 1 switch 6, and the pipe diameter to be probed 2 A gas pipe indicator light 9 that lights up when it is determined that the fluid 8 conducted by the pipe is gas, and a water pipe indicator light 10 that lights up when it is determined that the fluid 8 is water are attached.

The fluid discriminator main body 5 incorporates an electric circuit as shown in FIG. At J3 in FIG. 4, an oscillation circuit 11 is provided which oscillates a sine wave of several HIIZ, for example, and the sine wave oscillated by the oscillation circuit 11 is amplified to a predetermined amplitude by an amplifier circuit 12. A changeover switch 13 for switching the probe 1 between an ultrasound transmission state and an ultrasound reception state is controlled by a transmission/reception switching circuit 14, and when the start switch 6 is turned on, the impulse-like ultrasound is transmitted. The probe 1 is brought into contact with the lower contact on the sending Z side for a period of time, and is then switched to the receiving contact R when the probe 1 is switched to the receiving state.

Therefore, at the moment when the start switch 6 is turned on, the transmission/reception switching circuit 14 sets the changeover switch 13 to the transmission state and applies the output frequency of the amplifier circuit 12 to the probe 1. As a result, ultrasonic waves are emitted from the probe 1 in the form of impulses for a predetermined period of time, pass through the probe tube 2 and the fluid 8, are reflected at the bottom, and return to the probe 1 again. . The round trip time for the ultrasonic waves emitted from the probe 1 to reflect at the bottom of the probe tube 2 and return to the probe 1 is, for example, for a 4-inch diameter cast iron tube, i.e., a 100A type cast iron tube. case,
It is 0.14277L S and varies depending on the pipe diameter of the pipe 2 to be investigated. Therefore, the switching time during which the transmission/reception switching circuit 14 switches the changeover switch 13 from the contact T side to the contact R side is determined in accordance with the pipe diameter set by the pipe diameter selection switch 7, and the ultrasonic round trip time It is set to a slightly shorter time.

At the same time, the transmitting/receiving switching circuit 14 switches the changeover switch 13 to the receiving side contact R, and at the same time, the receiving circuit 15 detects the reception level of the probe 1 and determines whether the conducting fluid 8 of the probed tube 2 is gas or water. A receiving side switching signal is output to the receiving circuit 15 which determines whether the When the reception side switching signal is input, the reception circuit 15 automatically increases the measurement sensitivity, waits for the input of the reception signal from the probe 1, and responds to the case where the medium is water within a certain period of time, for example, 1 millisecond. When a received signal of a level higher than the set level is input, it is determined that the conductive fluid 8) in the pipe 2 to be investigated is water, and the water pipe indicator light 10 is turned on.

In addition, if the reception signal is not input within a certain period of time, it is determined that the attenuation of the ultrasonic wave is large, and the conduction fluid 8 of the probe tube 2 is
is determined to be gas, and the gas pipe indicator light 9 is turned on.

The transmitted waveform and received waveform of the ultrasonic wave are as shown in FIG. 5 when the fluid 8 is water, and as shown in FIG. 6 when the fluid 8 is gas. As shown in FIGS. 5 and 6, the reason why the transmitted waveform has multiple peaks is due to reflection from the tube material of the tube to be probed 2, and the reason why the received waveform has multiple peaks is due to the fact that the received waveform has multiple peaks. This is because the reflected waves go back and forth multiple times.

As described above, the fluid 8 corresponds to the reception level of the probe 1.
It is determined whether the pipe 2 is water or gas, and whether the pipe 2 to be investigated is a water pipe or a gas pipe is classified and displayed on indicator lights 9 and 10.

In the above embodiment, the probe 1 has the role of both transmitting and receiving ultrasonic waves, but as shown in FIG. The same effect can be obtained even if the transmitter 21 and receiver 22 are installed adjacently so that a reflection angle of about 30 degrees is obtained, as shown in FIG. 8. The effect of this can be obtained.

In this case, the changeover switch 13 of the fluid discriminator body 5 becomes unnecessary. Further, as shown in FIG. 9, it can be determined by measuring the attenuation rate of the reflected wave at the upper boundary surface between the fluid 8 and the probe tube 2.

(Effects of the Invention) As described above, according to the present invention, when ultrasonic waves pass through a medium, the attenuation rate differs depending on the type of medium.
This makes it possible to identify the fluid inside the pipe being investigated and determine the type of pipe being investigated, so when underground pipes are exposed during various types of construction work, it can be clearly determined whether they are gas pipes or water pipes. This has the effect of making construction work safer by distinguishing between the two.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams explaining the principle of the present invention, Figure 3 is an overall system diagram of an embodiment of the present invention, Figure 4 is its electric circuit block diagram, and Figures 5 and 6 are transmission waveforms. , received waveform diagrams, FIGS. 7, 8, and 9 are explanatory diagrams of other embodiments. 1... Probe 2... Tube to be investigated 5... Fluid discriminator body 7... Pipe diameter selection switch 8... Fluid 9... Gas pipe indicator light 10... Water pipe display light

Claims (2)

[Claims] (1) It is attached to the surface of the probe tube that conducts the fluid and emits ultrasonic waves, and after the emitted ultrasonic waves pass through the fluid as the main medium, it receives the ultrasonic waves that are reflected on the inner surface of the probe tube. In addition, a probe that outputs an electrical signal corresponding to the reception level and transmitting power for transmitting impulse-like ultrasonic waves from the probe are supplied to the probe. a fluid identification circuit that inputs the electrical signal output from the probe at a correspondingly set reception timing, and identifies and displays whether the fluid is water or gas based on an attenuation rate corresponding to the electrical signal; An ultrasonic gas pipe water pipe discriminator characterized by comprising: (2) The probe is separated into a transmitter that emits ultrasonic waves and a receiver that receives the transmitted or reflected ultrasonic waves after the emitted ultrasonic waves are transmitted or reflected through the fluid and the tube forming material to be investigated. An ultrasonic gas pipe water pipe discriminator according to claim 1, characterized in that: