JP2014109551A - Device and method for fluid identification - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluid identification technique which allows for receiving ultrasonic pulses that traverse a fluid in a tubular member with a good S/N ratio.SOLUTION: A fluid identification device comprises: a transmitter probe 2 which is placed on an outer peripheral surface 11 of a tubular member 1 containing a fluid therein to transmit an ultrasonic pulse in a traverse direction of the tubular member; a receiver probe 3 which is placed on the outer peripheral surface 11 to receive an in-fluid propagating ultrasonic pulse which is an ultrasonic pulse that traverses the fluid; a signal evaluation unit which determines a type of the fluid based on propagation time of the in-fluid propagating ultrasonic pulse that has traveled across the fluid; and an ultrasonic absorption member 4 which is mounted on the outer surface of the tubular member 1 between the transmitter probe 2 and the receiver probe 3 to absorb a wall body-propagating ultrasonic pulse which is an ultrasonic pulse that propagates along the peripheral wall of the tubular member 1.

Description

  The present invention relates to a fluid identification device and a fluid identification method for determining the type of fluid inherent in a tubular member.

  In the ground, tubular members such as a gas pipe for supplying city gas, a water pipe for supplying tap water, and a sewer pipe for collecting sewage are embedded. When performing soil excavation work, the tubular members may be exposed. In such a case, whether or not the exposed tubular member is used effectively, and if it is used effectively, the type of fluid flowing through the tubular member (for example, water or city gas) This is because it is necessary to take appropriate safety measures depending on the type of fluid flowing through the inside.

  A fluid identification device is known from Patent Document 1 in which the type of fluid contained in a tubular member is determined by non-destructive inspection without performing perforation. In this fluid identification device, a transmitting probe and a receiving probe facing each other are arranged on the outer peripheral surface of a tubular member, and an ultrasonic pulse transmitted from the transmitting probe causes a fluid in the tubular member to flow. The propagation speed of the ultrasonic wave is calculated from the time required to cross to reach the receiving probe. Since the propagation speed of ultrasonic waves, so-called sound speed, depends on physical properties such as the density and bulk modulus of the medium through which the ultrasonic waves propagate, the substance can be specified from the sound speed. Using this fact, the fluid identification device determines whether the fluid contained in the tubular member is water or city gas from the calculated sound velocity.

  The problem with the use of such a device is that, when the ultrasonic pulse transmitted from the transmitting probe is incident on the outer peripheral surface of the tubular member, most of the pulse wave propagates through the tube wall of the tubular member. Since it is decomposed into surface waves and propagates only through the tube wall to reach the receiving probe, it is received by the receiving probe as a noise wave having a high sound pressure level. For the measurement of the speed of sound required for the determination of the type of fluid based on the speed of sound, it is important to accurately detect the ultrasonic pulse that has reached the receiving probe across the fluid in the tubular member. It becomes an obstacle. In order to reduce the adverse effect of this noise wave, the fluid identification device according to Patent Document 1 includes a canceling probe that transmits a canceling wave that propagates through the tube wall and cancels the ultrasonic wave toward the receiving probe. ing.

  Unlike the technical field of determining the type of fluid existing inside the tubular member, in order to nondestructively detect a gas layer such as air contained in a fluid such as a liquid in the tube, ultrasonic waves are used. An in-pipe gas layer detection device to be used is known from Patent Document 2. This device emits ultrasonic waves from the outside of the tube in the diameter direction of the tube, receives the reflected echo of this ultrasonic wave, and detects the presence or absence of a gas layer that exists with the fluid in the tube. A sound absorbing material layer is provided on the outer peripheral surface, and ultrasonic waves are emitted from the outside of the sound absorbing material layer. This apparatus employs a so-called reflection echo method in which a single ultrasonic probe is used for both transmission and reception. In such a reflection echo method, since a reflection echo from the inner peripheral surface of the tube is repeated, a technique for determining the type of fluid existing in the tubular member based on the propagation time or speed of sound as in the present invention. It is practically difficult to apply. Furthermore, when an ultrasonic probe is arranged outside the sound absorbing material layer wound around the entire outer periphery of the tube and an ultrasonic pulse is transmitted from the sound absorbing material layer, the ultrasonic wave incident on the inside of the tube is absorbed by the sound absorbing material layer. The sound pressure of the sound wave pulse is reduced. In order to prevent this, when the thickness of the sound absorbing material layer is reduced, the ultrasonic pulse (noise wave) incident from the tube wall cannot be sufficiently absorbed, and it is reflected by the outer surface of the sound absorbing material layer and again the tube. The inconvenience of returning to the wall occurs.

2012-185083 Hei 11-183235

  As described above, in order to determine the type of fluid existing inside the tubular member, the application of the ultrasonic reflection method disclosed in Patent Document 2 is substantially impossible. Furthermore, the cancellation of the ultrasonic wave (plate wave or surface wave) propagating through the tube wall due to the cancellation wave from the canceling probe employed in the fluid identification device according to Patent Document 1 has a technical difficulty. High and the burden of equipment cost is large. For this reason, there is a need for a fluid identification technique that can reduce the noise wave without using a canceling probe and receive an ultrasonic pulse that traverses the fluid contained in the tubular member with a good S / N ratio. .

  A fluid identification device according to the present invention is disposed on an outer peripheral surface of a tubular member in which fluid is contained, and transmits a transmission probe that transmits an ultrasonic pulse in a transverse direction of the tubular member, and is transmitted from the transmission probe. A receiving probe disposed on an outer peripheral surface of the tubular member so as to receive a fluid propagating ultrasonic pulse that is an ultrasonic pulse propagating across the fluid; and the fluid propagating ultrasonic pulse A signal evaluation unit for determining the type of the fluid based on the propagation time propagated, and the probe for transmission to absorb a wall-propagating ultrasonic pulse that is an ultrasonic pulse propagating along the peripheral wall of the tubular member. And an ultrasonic absorbing member mounted on the surface of the tubular member between the receiver and the receiving probe.

  According to this configuration, the wall-propagating ultrasonic pulse, which is a plate wave or surface wave decomposed when the ultrasonic pulse transmitted from the transmission probe enters the outer peripheral surface of the tubular member, In the course of propagating through the wall, it is partially absorbed by the ultrasonic absorbing member mounted on the surface of the tubular member. As a result, the desired ultrasonic pulse can be received with a satisfactory S / N ratio without canceling the wall-propagating ultrasonic pulse (noise wave) due to the cancellation wave from the canceling probe, and accurate sound velocity measurement can be performed. The determination of the fluid type based on is realized.

  The fluid identification device according to the present invention can be used to specify the type of underground pipe that cannot distinguish between a gas pipe and a water pipe, that is, to determine whether the fluid flowing through the pipe is gas or water. Is suitable. Such a tubular member is mainly a circular tube, and its outer peripheral surface is curved with a relatively large curvature. For this reason, the ultrasonic absorbing member is required to have a property such that a noise wave (wall propagation ultrasonic pulse) propagating through the tube wall can be closely adhered to the outer peripheral surface so as to propagate to the ultrasonic absorbing member. The In order to satisfy this requirement, the ultrasonic absorbing member is preferably composed of a viscous ultrasonic absorbing member.

  In order for noise waves propagating through the tube wall to enter the ultrasonic absorbing member as smoothly as possible, it is better that the difference between the acoustic impedance of the tube wall and the acoustic impedance of the ultrasonic absorbing member is small. However, even if the acoustic waves are approximated to each other and noise waves are smoothly incident on the ultrasonic absorbing member, the noise waves are reflected again on the outer peripheral surface of the ultrasonic absorbing member and return to the tube wall to return to the tube wall. Incident light must be avoided. Therefore, it is preferable to reduce the sound pressure energy of the noise wave incident on the ultrasonic absorbing member within the ultrasonic absorbing member as much as possible by scattering or stepwise reflection. For this purpose, in one preferred embodiment of the present invention, the ultrasonic absorbing member is composed of a plurality of layers, and the acoustic impedance of each layer is closer to the acoustic impedance of the tubular member as the layer is closer to the outer peripheral surface of the tubular member. It is configured to reduce the difference between the two.

  When an underground pipe or the like is a fluid identification target, the ultrasonic absorbing member is contaminated with mud or the like and thus is used disposable. In such a case, it is preferable to prepare the ultrasonic absorbing member as a sheet molding material in order to simplify the operation of wrapping the ultrasonic absorbing member around the pipe outer peripheral surface every time.

  Furthermore, in order to increase the rate at which noise waves propagating through the tube wall are incident on the ultrasonic absorbing member, it is necessary to stably adhere the ultrasonic absorbing member to the outer peripheral surface of the tube wall. For this reason, in a preferred embodiment of the present invention, a fastener for pressing the ultrasonic absorbing member against the outer peripheral surface of the tubular member is provided. At this time, the fastener is preferably configured to press the ultrasonic absorbing member against the outer peripheral surface with an adjustable constant pressing pressure.

  In one specific embodiment of the signal evaluation unit for determining the type of fluid, the signal evaluation unit calculates the time for propagating the fluid from the propagation time of the fluid propagation ultrasonic pulse, and this calculation is performed. A sound speed calculation unit that calculates the sound speed of the fluid based on time; a determination unit that determines the type of the fluid from the calculated sound speed; and a notification unit that notifies a determination result of the determination unit. The ultrasonic pulse transmitted from the transmission probe and received by the reception probe not only propagates across the fluid, but also includes two on the side in contact with the transmission probe and the side in contact with the reception probe. Propagates in the radial direction through one tube thickness. Therefore, in order to accurately calculate the sound velocity of the fluid, the fluid propagation time for propagating the fluid that does not include the time for propagating the tube thickness portion is obtained, and the sound velocity of the fluid is calculated from the time and the inner diameter of the tubular member. The Since a reflected wave is generated between the inner peripheral surface of the tube and the fluid, the fluid propagation time can be obtained using this reflected wave. Since such propagation time measurement is a general measurement technique used for thickness measurement by ultrasonic waves, it can be used. The determination unit determines the type of fluid based on the calculated sound speed. At this time, it is convenient that the determination unit registers the sound speed of the fluid to be identified in advance.

  In addition, when the material and dimensions of the tubular member to be classified are known, and there are a plurality of types of liquids that are known in advance, ultrasonic pulses are transmitted from the transmission probe and received. It is preferable to classify the propagation time until it is received by the probe for use so that the fluid type to be identified is assigned. In this case, since the type of fluid can be determined depending on where the determined propagation time falls within this classified propagation time zone, the configuration of the evaluation unit can be simplified.

  The present invention is directed not only to the above-described fluid identification device, but also to a fluid identification method for identifying a fluid existing in a tubular member. The fluid identification method according to the present invention includes a step of arranging a transmission probe on an outer peripheral surface of a tubular member in which a fluid is present so as to transmit an ultrasonic pulse in a transverse direction of the tubular member, and the transmission probe. Disposing a receiving probe on the outer peripheral surface of the tubular member so as to receive a fluid-propagating ultrasonic pulse that is transmitted from the child and propagates across the fluid; An ultrasonic absorbing member is mounted on the surface of the tubular member between the transmitting probe and the receiving probe so as to absorb a wall-propagating ultrasonic pulse that is an ultrasonic pulse propagating along the peripheral wall. And determining a type of the fluid based on a propagation time during which the fluid-propagating ultrasonic pulse propagates through the fluid. The operational effects brought about by this fluid identification method are as described in the above-described fluid identification device. Various features described as preferred embodiments can also be applied to this fluid identification method.

It is a schematic diagram explaining the basic principle of the fluid identification apparatus by this invention, and is radial direction sectional drawing of the tubular member in fluid identification operation | work. It is a typical waveform diagram of an ultrasonic pulse transmitted in the radial direction of a tubular member. It is a perspective view which shows one of the embodiment of the fluid identification apparatus by this invention. It is a schematic diagram which shows the component of the fluid identification apparatus in the state which excluded the fastener. It is a wave form diagram of an ultrasonic pulse with an absorption member. It is a wave form diagram of an ultrasonic pulse without an absorption member.

The basic principle of sound velocity measurement employed in the fluid identification device according to the present invention will be described with reference to the schematic diagram of FIG.
A tubular member 1 shown in FIG. 1 is a conduit having a circular cross section, and a fluid such as city gas, air, LPG, water flows through the inside thereof. In some cases, fluid may stay inside the tubular member 1. The fluid identification device according to the present invention determines the type of fluid flowing through the tubular member 1 from the outer peripheral surface 11 of the tubular member 1 by nondestructive measurement using ultrasonic waves. Since the speed at which the ultrasonic wave propagates through the medium, that is, the speed of sound, differs depending on the physical property value, this is used in this measurement. Here, the probe 2 for transmitting an ultrasonic pulse is arranged on the outer peripheral surface 11 of the tubular member 1 so that the radiation center line of the ultrasonic pulse matches the diameter of the tubular member 1. Further, in order to receive an ultrasonic pulse transmitted from the transmitting probe 2 and propagating across the fluid existing in the tubular member 1, the outer peripheral surface 11 is located symmetrically with respect to the tube axis of the tubular member 1. The receiving probe 3 is disposed at the center. The sound speed measurement employed in the fluid identification device according to the present invention is the sound speed measurement by the transmission method, not the reflection method. Therefore, the time from when the ultrasonic pulse is transmitted from the transmission probe 2 to when the ultrasonic pulse is received by the reception probe 3 is measured as the ultrasonic propagation time. The speed of sound is obtained by dividing the length between the transmitting probe 2 and the receiving probe 3 by this ultrasonic wave propagation time. In this case, since the propagation time of the ultrasonic wave passing through the flow tubular member 1 in the radial direction is included, when only the propagation time of the ultrasonic wave passing through the fluid is obtained, the propagation time of the ultrasonic wave passing through the tubular member 1 is determined. It is necessary to deduct. If the tube thickness of the tubular member 1 and the material of the tubular member 1 are examined in advance, the ultrasonic propagation time can be estimated. The speed of sound of the fluid is considerably slower than cast iron, steel, or synthetic resin used for the tubular member 1, and the tube thickness of the tubular member 1 is shorter than the inner diameter. The ultrasonic wave propagation time including the ultrasonic wave propagation time of the tubular member 1 can be used as it is.

  In the fluid identification device configured as described above, a signal received by the receiving probe 3 includes an ultrasonic pulse propagating across the fluid existing in the tubular member 1 (here, a fluid propagation ultrasonic pulse). In addition, an ultrasonic pulse other than those shown in FIG. 1 (indicated by the symbol Wf) (herein also referred to as wall-propagating ultrasonic pulses or noise waves, and in FIG. 1 by the symbol Wn) is included. is there. Although the noise wave is also schematically shown in FIG. 1, the ultrasonic pulse transmitted from the transmission probe 2 is decomposed into a plate wave and a surface wave, and the decomposed ultrasonic wave is Then, it diffuses along the tube wall (side wall of the tube), reaches the receiving probe 3 and is received. Since the sound velocity of the noise wave propagating through the tubular member 1 manufactured from steel, cast iron, or synthetic resin is considerably faster than that of the fluid, it propagates across the fluid even if the propagation distance is about 1.5 times longer. The probe 3 for reception is reached earlier than the ultrasonic pulse. Further, the noise wave further goes around the tubular member 1 and reaches the receiving probe 3 again. FIG. 2 schematically shows a waveform diagram of an ultrasonic signal received by the receiving probe 3. In FIG. 2, the first noise wave is marked with a symbol Wn1, and the noise wave received once around is marked with a symbol Wn2. The waveform of the ultrasonic pulse that propagates across the fluid is marked with the symbol Wf.

  Since the noise wave is absorbed while the noise wave (wall-propagating ultrasonic pulse) propagates along the tube wall of the tubular member 1, the ultrasonic absorbing member 4 is connected to the transmitting probe 2 and the receiving probe. It is attached to the outer surface 11 of the tubular member 1 between the touch elements 3. In order for noise waves to efficiently enter the ultrasonic absorbing member 4 from the tubular member 1, the material of the ultrasonic absorbing member 4 is selected as close as possible to the acoustic impedance of the tubular member 1. Further, in order to improve the adhesion of the tubular member 1 to the outer surface 11, it is preferable that the tube member 1 has a viscosity with a degree of flexibility that matches the curvature of the outer surface 11. Furthermore, there is an advantage in using a material having a sound absorbing characteristic in order to absorb a noise wave incident on the ultrasonic absorbing member 4 or forming a sound absorbing structure (a porous structure or a granular material mixed structure). As an example, it is also preferable that the ultrasonic absorbing member 4 is composed of a plurality of layers formed so that the difference in acoustic impedance of the tubular member 1 is smaller as the acoustic impedance of each layer is closer to the outer peripheral surface of the tubular member 1. is there. In order to further improve the adhesion of the ultrasonic absorbing member 4 to the outer surface 11 of the tubular member 1, a fastener that presses the ultrasonic absorbing member 4 against the outer peripheral surface of the tubular member 1 is used. Suitable ultrasonic absorbing members 4 include oil clay, putty, rubber sheet, plastic (PP) sheet, non-woven fabric, etc., or a composite material combining them.

  As schematically shown in FIG. 1, a noise wave (indicated by symbol Wa in FIG. 1) incident on the ultrasonic absorbing member 4 from the tubular member 1 is absorbed by the ultrasonic absorbing member 4 by scattering or the like. The sound pressure energy is lost. Thereby, the noise wave as the ultrasonic signal received by the receiving probe 3 is considerably attenuated. Note that FIG. 2 is for illustrative purposes, and the waveform is deformed for easy understanding.

A fluid identification method will be described with reference to FIG. In the waveform diagram of the ultrasonic pulse shown in FIG. 2 with the time axis on the horizontal axis, the time point when the ultrasonic pulse is transmitted by the transmission probe 2 is indicated by Ts (usually 0 seconds). The pseudo pulse W0 is displayed for easy understanding. Further, the waveform of the first noise wave is indicated by Wn1, the waveform of the second noise wave is indicated by Wn2, and the arrival time points at the respective reception probes 3 are indicated by Twn1 and Twn2. The waveform of the fluid propagation ultrasonic pulse is indicated by Wf, and the arrival time is indicated by Twf.
The propagation time of the fluid propagation ultrasonic pulse: t0 can be obtained by t0 = Twf-Ts. If the outer diameter of the tubular member 1 is D, the fluid propagation ultrasonic pulse including the tubular member 1 is represented by D / t0. Sound speed is obtained. In order to obtain the sound velocity of the fluid propagation ultrasonic pulse not including the tubular member 1, the propagation time of the tubular member 1: the propagation time after subtracting Δt: t = t 0 −2Δt is obtained, and the inner diameter of the tubular member 1 is set to d. For example, the sound velocity of only the fluid can be calculated by d / t. The propagation time of the tubular member 1: Δt may be an estimated value or may be calculated from the thickness and material of the tubular member 1. If the sound velocity of the fluid to be identified is significantly different from the sound velocity of the tubular member, the influence thereof is small. Therefore, the fluid type may be determined based on the above-mentioned sound velocity: D / t0. What is important in this fluid identification device is that the ultrasonic wave absorbing member 4 attenuates the noise wave as much as possible to obtain the rising waveform of the fluid propagation ultrasonic pulse as clear as possible.

  In addition, since the ultrasonic pulse is more strongly reflected at the boundary surface as the difference in acoustic impedance of the medium forming the boundary surface is larger, here, a large reflection occurs at the boundary surface between the fluid and the inner peripheral surface of the tubular member 1. . Therefore, in the waveform diagram of FIG. 2, the receiving probe 3 receives not only the waveform of the first fluid propagation ultrasonic pulse (indicated by Wf) but also the fluid in the tubular member 1. Also shown is the waveform of a fluid-propagating ultrasonic pulse that is reciprocated once and a half (shown as Wf2). The arrival time of such a fluid propagating ultrasonic pulse is indicated by Twf2. If the waveform indicated by Wf2 can be detected with a better signal-to-noise ratio than the waveform indicated by Wf, this waveform is used to calculate the propagation time (Twf2-Ts = t0 + 2 × t0 = 3t0). Based on this, the fluid type can be determined.

  Next, one specific embodiment of the fluid identification device according to the present invention will be described with reference to the drawings. FIG. 3 is a perspective view illustrating the overall configuration of the fluid identification device, and FIG. 4 is a schematic diagram illustrating the components of the fluid identification device in a state in which the fastener is omitted.

  The fluid identification device shown in FIGS. 3 and 4 implements the basic principle described with reference to FIGS. 1 and 2, and the outer surface of the conduit 1 such as a water pipe or gas pipe as a tubular member. 11 includes a transmitting probe 2 and a receiving probe 3, which are disposed opposite to each other, an ultrasonic processing unit 5, an ultrasonic absorbing member 4, and a fastener 6. A shoe member 31 for matching the curved surface of the conduit 1 is mounted on the ultrasonic excitation surfaces of the transmission probe 2 and the reception probe 3. The ultrasonic absorbing member 4 is made of oil clay, is formed into a sheet shape having a thickness of several millimeters and a width of about 30 cm, and is wound around the outer surface 11 of the conduit 1 without a gap. However, the ultrasonic wave absorbing member 4 transmitting probe 2 can be placed directly on the outer surface 11 of the conduit 1 at the place where the transmitting probe 2 and the receiving probe 3 of the ultrasonic absorbing member 4 are installed. Is provided with an opening 41.

  The fastener 6 is configured to press the wound ultrasonic absorbing member 4 entirely against the conduit 1, and pulls the strip 61 and the free ends of the strip 61 to the strip 61. It consists of tightening bolts that give tension. By tightening the tightening bolt, the tension of the belt-like body 61 is increased, and the ultrasonic absorbing member 4 is tightened by a force inward in the radial direction. The tightening torque is about 10 N · m. Also in the belt-like body 61, an opening 31 a is provided so as not to interfere with the transmission probe 2 and the reception probe 3 installed in the conduit 1. When the fastener 6 is attached, the axial and circumferential positions of the strip 61 with respect to the conduit 1 are adjusted so that the opening 41 of the ultrasonic absorbing member 4 and the opening 63 of the strip 61 match. . In order to improve the adhesion between the outer surface 11 of the conduit 1 and the ultrasonic absorbing member 4, it is also preferable to interpose a coupling agent such as glycerin or lubricating oil therebetween.

  As shown in FIG. 4, the ultrasonic processing unit 5 is based on the propagation time that the fluid propagation ultrasonic pulse transmitted from the transmission probe 2 and received by the reception probe 3 propagates through the fluid. In order to determine the type of fluid present in the conduit 1, a transmission circuit 51, a reception circuit 52, a signal evaluation unit 53, a data storage unit 54, and a display unit 55 are provided. The transmission circuit 51 generates a high-voltage pulse to excite the piezoelectric element of the transmission probe 2 to generate an ultrasonic pulse. The receiving circuit 52 performs preprocessing for performing amplification, frequency selection, and the like on the signal received by the receiving probe 3. The display unit 55 is a display such as a liquid crystal that displays the waveform of the ultrasonic pulse and other information.

  The signal evaluation unit 53 includes a propagation time calculation unit 53a that calculates the time for propagation of the fluid from the propagation time of the fluid propagation ultrasonic pulse, a sound speed calculation unit 53b that calculates the sound speed of the fluid based on the calculated propagation time, A determination unit 53c that determines the type of the fluid from the sound speed calculated by the calculation unit 53b, and a notification unit 53d that generates a notification signal for notifying the determination result of the determination unit are included. Here, the propagation time handled by the propagation time calculation unit 53a is not strictly limited to the time for the ultrasonic pulse to propagate through the fluid, and the total propagation time including the time for propagation through the conduit 1 is not limited. It may be included. When the conduit propagation time can be estimated, an accurate fluid propagation time can be obtained by subtracting the conduit propagation time from the calculated propagation time. In this embodiment, since the conduit propagation time does not significantly affect the fluid type determination, the propagation time handled by the propagation time calculation unit 53a is determined from the time when the ultrasonic pulse is transmitted by the transmission probe 2 for reception. This is the time until the point of reception by the probe 3. However, as described above, when a true transmitted ultrasonic pulse without reflection (indicated by Wf in the waveform diagram of FIG. 2) is not detected with a good S / N ratio, 1 in the conduit 1 An ultrasonic pulse (represented by Wf2 in the waveform diagram of FIG. 2) that has been reciprocated once and a half times is used. The mechanism of operation in the propagation time calculation unit 53a and the sound speed calculation unit 53b is widely used in ultrasonic sound velocity measuring devices and ultrasonic wall thickness measuring devices. Reference 1 is referred to.

  The determination unit 53c accesses the data storage unit 54, searches for a fluid type having the sound speed most similar to the sound speed calculated by the sound speed calculation unit 53b, and determines that the fluid type that matches the search is a fluid existing in the conduit 1. To do. Various modifications can be made to the algorithm executed by the determination unit 53c. For example, if the propagation time corresponding to each fluid to be identified is stored in the data storage unit 54 according to the material, inner diameter, and thickness of the conduit 1, the sound speed calculation unit 53b is omitted, and the propagation time calculation unit 53a It is also possible to determine the fluid type directly from the calculated propagation time. When the determination unit 53c determines the fluid type inherent in the conduit 1, the notification unit 53d generates a display signal for displaying the determined fluid type on the display unit 55. Further, the notification unit 53d may be configured to notify the determined fluid type by voice, buzzer, or lamp.

In the fluid identification device of the above-described embodiment, a measurement experiment was performed on a cast iron conduit 1 having a pipe outer diameter of 118 mm and a pipe thickness of 8.5 mm in which atmospheric air was present. As for the frequencies of the transmission probe 2 and the reception probe 3, appropriate ones differ depending on the material of the conduit 1 and the tube thickness. Therefore, the transmission probe 2 and the reception probe of several kinds of frequencies are used. It is preferable to prepare a child 3 and select one that provides the best S / N ratio.
The ultrasonic waveforms obtained in this experiment are shown in FIGS. FIG. 5 is an ultrasonic waveform obtained when the ultrasonic absorbing member 4 is tightened with a tightening torque of 10 Nm using the tightening tool 6. FIG. 6 is an ultrasonic waveform obtained when the ultrasonic absorbing member 4 is used for reference. As can be read from the ultrasonic waveform of FIG. 5, the waveform of the fluid propagation ultrasonic pulse (indicated by Wf 2) received by the receiving probe 3 after reciprocating once and half inside the conduit 1 (air). The arrival time (indicated by Twf2) is 920 μs. Since the speed of sound of cast iron is 3000 to 5000 m / s, the time for the ultrasonic pulse to propagate through the conduit 1 is 5 μs or less, and may be ignored, or the amount may be subtracted from Twf2. Since the inner diameter of the conduit 1 is 101 mm and the propagation time has propagated it three times, the sound speed is calculated to be about 330 m / s. That is, from this sound speed result, it can be determined that the fluid contained in the conduit 1 is air. Incidentally, it can be read from FIG. 4 that it is difficult to detect the waveform of the fluid-propagating ultrasonic pulse due to interference by noise waves without the ultrasonic absorbing member 4.

  The present invention can be applied to a fluid identification device that identifies the type of fluid inherent in a tubular member from the outside of the tubular member by a non-destructive method.

1: Conduit (tubular member)
2: Transmission probe 3: Reception probe 4: Ultrasonic absorbing member 5: Ultrasonic processing unit 51: Transmission circuit 52: Reception circuit 53: Signal evaluation unit 53a: Propagation time calculation unit 53b: Sound velocity calculation unit 53c: Determination unit 53d: Notification unit 54: Data storage unit 6: Fastening tool

Claims (7)

A transmitting probe that is disposed on an outer peripheral surface of a tubular member in which a fluid is present and transmits an ultrasonic pulse in a transverse direction of the tubular member;
A receiving probe disposed on an outer peripheral surface of the tubular member so as to receive a fluid propagating ultrasonic pulse transmitted from the transmitting probe and propagating across the fluid;
A signal evaluation unit that determines the type of the fluid based on a propagation time during which the fluid propagation ultrasonic pulse propagates through the fluid;
Attached to the surface of the tubular member between the transmitting probe and the receiving probe to absorb wall-propagating ultrasonic pulses, which are ultrasonic pulses propagating along the peripheral wall of the tubular member. An ultrasonic absorbing member,
A fluid identification device comprising:   The fluid identification device according to claim 1, wherein the ultrasonic absorbing member is a viscous ultrasonic absorbing member.   3. The fluid identification device according to claim 1, wherein the ultrasonic absorbing member includes a plurality of layers, and the acoustic impedance of each layer has a smaller difference from the acoustic impedance of the tubular member as the layer is closer to the outer peripheral surface of the tubular member.   The fluid identification device according to any one of claims 1 to 3, wherein the ultrasonic absorbing member is a sheet molding material.   The fluid identification device according to any one of claims 1 to 4, further comprising a fastener that presses the ultrasonic absorbing member against an outer peripheral surface of the tubular member.   The signal evaluation unit calculates a time for propagating the fluid from a propagation time of the fluid propagation ultrasonic pulse, and calculates a sound speed of the fluid based on the calculated time, and a calculated sound speed The fluid identification device according to claim 1, further comprising: a determination unit that determines a type of the fluid from a determination unit; and a notification unit that notifies a determination result of the determination unit. Disposing a transmitting probe on an outer peripheral surface of a tubular member in which fluid is present so as to transmit an ultrasonic pulse in a transverse direction of the tubular member;
Disposing a receiving probe on the outer peripheral surface of the tubular member so as to receive a fluid propagating ultrasonic pulse, which is an ultrasonic pulse transmitted from the transmitting probe and propagating across the fluid. When,
An ultrasonic wave is applied to the surface of the tubular member between the transmitting probe and the receiving probe so as to absorb a wall-propagating ultrasonic pulse that is an ultrasonic pulse propagating along the peripheral wall of the tubular member. Attaching the absorbent member;
Determining the type of the fluid based on a propagation time during which the fluid-propagating ultrasonic pulse has propagated through the fluid;
A fluid identification method comprising:

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