JP2005265747A - Piping system identification method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piping system identification method for simply and accurately performing identification even when a piping system including an inner pipe incapable of inserting a microphone in a pipe exists. <P>SOLUTION: In the piping system identification method, a first part M1 and a second part M2 provided on a plurality of pieces of branched piping from among the piping system including main piping 1 and the plurality of the pieces of the branched piping connected through a connection part 2 on the main piping 1 are identified to belong to the same or different branched piping system. The piping system identification method includes a measuring step for measuring a signal arrival time until an inspection signal transmitted from a transmission part is received on a receiving part respectively, and a determination step for determining the same or the difference of the branched piping to which the first part and the second part belong on the basis of the signal arrival time by making one part from among three parts of the first part M1, the second part M2 and the connection part 2 the transmission part, and making the other parts the receiving part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a piping system identification method for identifying an individual piping system from a piping system including a plurality of pipes. More specifically, the present invention relates to piping system identification for easily, accurately and reliably identifying a plurality of branch pipes (supply pipes) connected to a main pipe (main pipe) used in a gas piping system or the like. Regarding the method. The present invention can be used, for example, to identify the system of the inner pipe.

  Multiple gas pipes arranged in large buildings (for example, office buildings, commercial facilities, factories, etc.) and apartment houses (for example, condominiums, apartments, etc.) form a piping system that is complicated under floors and walls. It may be stretched around. When constructing gas piping work in such a building, stop supplying gas to all gas pipes, or identify in advance which piping system the gas pipe to be constructed belongs to, and the corresponding piping It is necessary to stop the gas supply only for.

  However, stopping gas supply to all parts of the building has a significant impact on corporate activities and daily life. After confirming this, gas piping work is often performed.

  Conventionally, as a piping system identification method performed prior to the above gas piping work, for example, there has been a human visual confirmation of a pipe connection state.

  However, the gas piping is complicatedly stretched under the floor and inside the wall, and it has been necessary to take a great deal of time to accurately grasp the connection state of the piping visually.

  As another piping system identification method, there is a method in which a pressure gauge is connected to the downstream side of the piping, and the change in the internal pressure of the pipe is observed while gradually closing the upstream valve.

  However, the confirmation method by observing the change in the pressure in the pipe has a problem that the work efficiency is poor because it is forced to carry out the work while communicating with the radio when the distance between the valve and the pressure gauge is long. . Further, since delicate operation is required for adjusting the valve, accurate and quick confirmation work is difficult. Furthermore, if the valve is fully closed due to an erroneous operation by the operator, an opening work is required, which takes a lot of time and effort.

  Therefore, in order to solve such problems, a pipe connection confirmation method using sound waves, that is, in a gas pipe forming a pipe system, a sound wave is incident from one place and a sound wave propagating therefrom is placed in another place. There has been proposed a pipe connection confirmation method for detecting with two microphones, comparing the intensity or detection time of sound waves detected with each microphone, and identifying pipes based on the intensity difference or time difference (for example, Patent Document 1). reference).

JP 2002-365371 A

  The method of Patent Document 1 confirms the connection state of the pipe between the striking point and the microphone by directly measuring the sound in the tube with a microphone inserted into the tube by striking or the like and inserting the sound wave into the tube. Is the method.

  However, when determining whether two meters are downstream (same system) or one is downstream and the other is upstream (different system) for one service cock, the service cock has a microphone. There is no mouth to insert.

  Therefore, in order to apply the method of Patent Document 1, only a method of inserting a microphone into each of the pressure detection holes of the two meters and generating a striking sound with the service cock can be taken. In principle, discrimination is impossible because sound propagates to both the downstream side and the downstream side.

  Therefore, the present invention has been made in view of the above problems, and can easily and accurately identify a piping system including a piping such as an inner tube in which a microphone cannot be inserted into the tube. It is an object of the present invention to provide a piping system identification method capable of performing the above.

  A characteristic configuration of the piping system identification method according to the present invention is a first configuration provided on a plurality of branch pipes from a pipe system including a main pipe and a plurality of branch pipes connected to the main pipe via connection portions. A piping system identification method for identifying that one part and a second part belong to the same or different branch piping system, the three parts including the first part, the second part, and the connection part A measuring step of measuring a signal arrival time until an inspection signal transmitted from the transmitting part is received at the receiving part, in which one part is a transmitting part and the other part is a receiving part. And a determination step of determining the difference between the branch pipes to which the first part and the second part belong based on the signal arrival time measured in the measurement step.

  In the piping system identification method of this configuration, the first part, the second part, and the connection part on the branch pipe are parts that are exposed to the outside, and such exposed parts are designated as the inspection signal transmission part and the reception part. Therefore, even in a piping system in which most of the inner pipe is embedded, the branch piping system can be easily and reliably identified. In addition, since it is possible to determine the difference between branch pipes using only the measurement results of the signal arrival time between each part, it is possible to easily identify the branch pipe system without using a special measuring device or the like. Can do.

  In the piping system identification method of the present invention, in the measurement step, the first part and the second part can be used as the transmission part.

  In the piping system identification method of this configuration, the first part and the second part exposed to the outside are used as transmission parts, so that the system of the branch pipe can be easily and easily identified without performing troublesome preparation work. Can do.

  In the piping system identification method of the present invention, as the determination step, the first signal arrival time between the first part and the connection part among the signal arrival times is determined by the first part and the second part. It is also possible to execute a first determination step in which it is determined that the branch pipe to which the first part and the second part belong is in the same system when the third signal arrival time between the two parts is larger.

  In the piping system identification method of this configuration, when the first signal arrival time is longer than the third signal arrival time, it can be determined that the branch piping to which the first part and the second part belong is the same system. Therefore, it is possible to easily and easily identify the branch piping system.

  In the piping system identification method of the present invention, as the determination step, when the second signal arrival time between the second part and the connection part is larger than the third signal arrival time in the signal arrival time. In addition, it is also possible to execute a second determination step for determining that the branch pipe to which the first part and the second part belong are of the same system.

  In the piping system identification method of this configuration, when the second signal arrival time is longer than the third signal arrival time, it can be determined that the branch piping to which the first part and the second part belong is the same system. Therefore, it is possible to easily and easily identify the branch piping system.

  In the piping system identification method of the present invention, as the determination step, the transmission part is changed in the measurement step, and signal arrival times between the three parts are respectively measured. When the sum of one signal arrival time and the second signal arrival time is larger than the third signal arrival time, a third pipe for determining that the branch pipe to which the first part and the second part belong is in the same system. It is also possible to execute a determination step.

  In the piping system identification method of this configuration, since the signal arrival time between the three parts is measured by changing the transmission part, it is possible to identify the branch piping system in more detail. When the sum of the signal arrival time and the second signal arrival time is greater than the third signal arrival time, it can be determined that the branch pipe to which the first part and the second part belong is the same system, The branch piping system can be easily identified.

  In the piping system identification method of the present invention, as the determination step, the first signal arrival time between the first part and the connection part among the signal arrival times is determined by the first part and the second part. A first determination step of determining that the branch pipe to which the first part and the second part belong is of the same system when the third signal arrival time is greater than the third signal arrival time, and among the signal arrival times, When the second signal arrival time between the two parts and the connection part is larger than the third signal arrival time, it is determined that the branch pipe to which the first part and the second part belong is in the same system. In the second determination step and the measurement step, the transmission part is changed to measure the signal arrival times between the three parts, and among the signal arrival times, the first signal arrival time and the second signal arrival time are measured. signal It is also possible to execute a third determination step for determining that the branch pipe to which the first part and the second part belong are in the same system when the sum of the arrival times is larger than the third signal arrival time. It is.

  In the piping system identification method of this configuration, the branch piping system can be determined by combining the first determination step, the second determination step, and the third determination step. Is possible.

  In the piping system identification method of the present invention, the first determination step and the second determination step are executed before the third determination step, and the third determination step includes the first signal arrival time and the second determination step. When the sum of the signal arrival times is larger than the third signal arrival time and smaller than twice the third signal arrival time, the branch pipe to which the first part and the second part belong is the same system. It is also possible to be a step of determining.

  In the piping system identification method of this configuration, since the first determination step and the second determination step are executed before the third determination step, the determination of the branch piping system can be performed efficiently. Further, when the sum of the first signal arrival time and the second signal arrival time is larger than the third signal arrival time and smaller than twice the third signal arrival time, the branch to which the first part and the second part belong Since it can be determined that the piping is the same system, the branch piping system can be easily and easily identified.

  In the piping system identification method of the present invention, the determination step executes the first determination step, the second determination step, and the third determination step, whereby the branch to which the first portion and the second portion belong. When it is not determined that the piping is the same system, it may be a step of determining that the branch piping is a different system.

  In the piping system identification method of this configuration, the branch piping to which the first part and the second part belong is determined to be a separate system from the results of the first determination step, the second determination step, and the third determination step. Therefore, the branch piping system can be easily and easily identified.

  In the piping system identification method of the present invention, the inspection signal may include a chirp wave.

  In the piping system identification method of this configuration, since a chirp wave is used as an inspection signal, it is possible to obtain a clear impulse signal by performing pulse compression processing on the inspection signal, thereby identifying the branch piping system Can be performed more easily.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the structure described in the following embodiment and drawing.

[Inner pipe]
FIG. 1 is a simplified piping schematic diagram for explaining a piping system specifically intended for an inner pipe. In this inner pipe, a branch pipe 3 is connected to a main pipe 1 via a service cock 2 which is a connection part. As shown in FIG. 1, the service cock 2 is usually provided at or near the branch portion between the main pipe 1 and the branch pipe 3. Further, the branch pipe 3 is provided with a meter M1 as a first part. Here, it is known that the meter M1 belongs to the branch pipe 3. In addition, the same inner pipe is provided with a meter M2 as a second part, which is not known to which piping system belongs. Incidentally, when the meter M2 is in the same system as the meter M1, the meter M2 is connected to the branch pipe 3 by the pipe Q. When the meter M2 is a separate system from the meter M1, the meter M2 is connected to the pipe. It is connected to the main pipe 1 by P.

  In the present embodiment, in order to make the explanation easy to understand, the main pipe 1 and the branch pipe 3 are orthogonal to each other in the drawing, and the service cock 2 is set at the origin and branch to facilitate understanding of the positional relationship of each part. The pipe 3 is regarded as the x axis and the main pipe 1 is regarded as the y axis. Then, as an example, the investigation of the inner pipe is performed in a region of 0 m ≦ x ≦ 50 m and 0 m ≦ y ≦ 50 m.

  In practice, the area of 0 m ≦ x ≦ 2 m and 0 m ≦ y ≦ 2 m is excluded from the investigation due to the measurement accuracy, but the description of this embodiment is the description of the measurement principle of the piping system identification method. Since the emphasis is placed on the above, the area not subject to the survey based on the above measurement accuracy is not considered here.

[Piping system identification system]
First, the piping system identification system for implementing the piping system identification method of this invention is demonstrated. The investigation object exemplified in this embodiment is an inner tube in the state of FIG. This embodiment will be described more specifically with reference to FIG.

  FIG. 2 is a schematic piping diagram showing an inner pipe in which the piping system identification system 100 of the present invention is installed. The meter M1 is provided with a speaker 11 as a signal transmitting means and a vibration measuring device 12 as a signal receiving means, and the meter M2 is provided with a speaker 13 as a signal transmitting means and a vibration measuring device 14 as a signal receiving means. The service cock 2 is provided with a vibration measuring device 15 as signal receiving means. Thereby, the piping system identification system 100 can measure the signal arrival time between the three parts of the meter M1, the meter M2, and the service cock 2. Specifically, the measurement results measured by the vibration measuring devices 12, 14, 15 at each part are transmitted to the computer 20, and the signal arrival time between the three parts is measured by the measuring means 21 in the computer 20. Based on this signal arrival time, the determination means 22 in the computer 20 can determine the difference between the branch pipes to which the meters M1 and M2 belong. Hereinafter, the determination method performed by the determination unit 22 will be specifically described step by step.

[Piping system identification method]
First, the measurement step of measuring the arrival time of the inspection signal between each part is performed by the measuring means 21. In this measurement step, one of the three parts of the meter M1, the meter M2, and the service cock 2 is basically used as a test signal transmission part and the other part as a reception part. It is also possible to change and measure the signal arrival time between the three parts.

Regarding this measurement result, the arrival time until the inspection signal is transmitted from the meter M1 and received by the service cock 2 is T _m1s , the arrival time until the inspection signal is transmitted from the meter M2 and received by the service cock 2 is T _m2s , and the meter M1 The arrival time from transmission from (or meter M2) to reception by meter M2 (or meter M1) is defined as T _mm .

  In addition, since the arrival time of the inspection signal from the meter M1 to the meter M2 and the arrival time of the inspection signal from the meter M2 to the meter M1 are the same in principle, it is handled in this embodiment as well. .

(First determination step)
This step is a determination step when an inspection signal is transmitted from the meter M1 and received by the meter M2 and the service cock 2. If the meter M1 and the meter M2 are different systems, that is, if the meter M2 is connected to the branch pipe P in FIG. 1, it is clear that the relationship of T _m1s <T _mm is established. Therefore, if the relationship of T _m1s > T _mm is established in this step according to the contradiction theorem, the determination means 22 determines that the meter M1 and the meter M2 are in the case where the meter M2 exists in the hatched area in FIG. It can be determined that the system is always the same. Thus, if this step is used, the branch piping system can be identified easily and easily. If T _m1s <T _mm , the process proceeds to the next step.

(Second determination step)
This step is a determination step when an inspection signal is transmitted from the meter M2 and received by the meter M1 and the service cock 2. If the meter M1 and the meter M2 are separate systems, that is, in FIG. 1, the meter M2 is connected to the branch pipe P, it is clear that the relationship of T _m2s <T _mm is established. Therefore, if the relationship of T _m2s > T _mm is established in this step according to the contradiction theorem, the determination unit 22 determines that the meter M1 and the meter M2 are in the case where the meter M2 exists in the hatched area in FIG. It can be determined that the system is always the same. Thus, if this step is used, the branch piping system can be identified easily and easily. If T _m2s <T _mm , the process proceeds to the next step.

(Third determination step)
The conditions in which the meter M1 and the meter M2 are not determined to be in the same system in the first determination step and the second determination step are when T _m1s <T _mm and T _m2s <T _mm . However, even in such a case, it cannot be determined that the meter M1 and the meter M2 are necessarily separate systems. Therefore, the difference between the piping systems of the meters M1 and M2 will be examined in more detail using the model shown in FIG.

  FIG. 5 is a model diagram schematically showing the difference between the piping systems in the inner pipe. (A) of FIG. 5 is a model which shows the positional relationship of each site | part when meter M1 and meter M2 are the same systems, (b) is a case where meter M1 and meter M2 are another systems. It is a model which shows the positional relationship of each site | part. The symbol a in the figure indicates the y-coordinate value of the meter M2, b indicates the x-coordinate value of the meter M2, and c indicates the length of the pipe corresponding to the x-coordinate value of the meter M1.

Since the length of the pipe can be expressed as the product of the signal arrival time and the signal propagation speed v, when the meter M1 and the meter M2 are in the same system, the signal arrival time between the parts is shown in FIG. )Than,
T _m1s · v = c (1)
T _m2s · v = a + b (2)
T _mm · v = a + (c−b) (3)
It is clear that

Further, from the condition that the meter M1 and the meter M2 are not determined to be the same system, T _m1s <T _mm and T _m2s <T _mm ,
a> b and c> 2b (4)
It is also clear that

Here, when (1) + (2)-(3) is calculated,
(T _m1s + T _m2s −T _mm ) · v = c + (a + b) − (a + (c−b))
= 2b
= B + 2b−b (5)
When the condition of (4) is applied to (5),
T _m1s + T _m2s −T _mm <(a + c−b) / v = T _mm (6)
Can guide you.

Therefore, from (6)
T _m1s + T _m2s <2T _mm (7)
Is obtained. This (7) is one of the conditions that the meter M1 and the meter M2 are in the same system.

On the other hand, when the meter M1 and the meter M2 are different systems, the signal arrival time between each part is as shown in FIG.
T _m1s · v = c (8)
T _m2s · v = a + b (9)
T _mm · v = a + b + c (10)
It is clear that

Moreover, the signal arrival time between each part is shown in FIG. 5 (b) and the relationship of (8), (9), (10),
T _m1s + T _m2s = T _mm (11)
Is obtained. This (11) is a condition that the meter M1 and the meter M2 are separate systems.

Then, since the condition that the meter M1 and the meter M2 are in the same system does not hold the equal sign of (11),
T _mm <T _m1s + T _m2s (12)
become that way.

When (12) and (7) are combined,
_{T mm <T m1s + T m2s} <2T mm (13)
It can also be expressed as

  Note that the range of (13), which is a condition that the meter M1 and the meter M2 are in the same system, is an area indicated by hatching in FIG.

  In this way, in this step, since the signal arrival time between the three parts is measured by changing the transmission part, it is possible to identify the branch piping system in more detail, and more simply and easily. The branch piping system can be identified.

  As described above, the piping system identification method has been specifically described in the first determination step, the second determination step, and the third determination step. Here, the difference between the first determination step and the second determination step is the difference in whether the part that transmits the inspection signal is the meter M1 or the meter M2, and the determination method itself is performed by the same method. Yes. Then, in the piping system identification method of the present invention, the same result can be obtained regardless of which step is executed first in the order of the first determination step and the second determination step.

  Further, when the branch piping system is determined by combining the first determination step, the second determination step, and the third determination step as in this embodiment, detailed identification is possible. In particular, if the first determination step and the second determination step are executed before the third determination step, it is possible to efficiently determine the branch piping system.

  Furthermore, in the piping system identification method of the present invention, when the first determination step, the second determination step, and the third determination step are executed, it is not determined that the branch piping to which the meter M1 and the meter M2 belong is the same system. Since it can also be determined that the branch pipe is a separate system, the branch pipe system can be easily and easily identified.

  Furthermore, in the piping system identification method of the present invention, the meter M1, the meter M2, and the service cock 2 on the branch pipe are parts exposed to the outside, and such exposed parts are detected as inspection signals. Since it is used as a transmission part and a reception part, it is possible to easily and reliably identify a branch pipe system even in a pipe system in which most of the inner pipe is embedded. In addition, since it is possible to determine the difference between branch pipes using only the measurement results of the signal arrival time between each part, it is possible to easily identify the branch pipe system without using a special measuring device or the like. Can do. Here, in particular, when the meter M1 and the meter M2 are transmitted, it is possible to easily and easily identify the branch piping system without performing troublesome preparation work.

By the way, it can be said that the piping system identification method by the first determination step, the second determination step, and the third determination step is a method suitable for implementation in an actual measurement site in consideration of measurement accuracy and the like. . However, theoretically, the signal arrival time between the meter M1 and the service cock 2 (first signal arrival time: T _m1s ), the signal arrival time between the meter M2 and the service cock 2 (second signal arrival time) : T _m2s ) and the relationship between the signal arrival time (third signal arrival time: T _mm ) between the meter M1 and the meter M2, it is possible to determine the piping system. Specifically, when the sum of the first signal arrival time and the second signal arrival time is larger than the third signal arrival time, it can be determined that the meter M1 and the meter M2 are in the same system.

Therefore, when the measurement accuracy of the arrival time is sufficiently high, it is only necessary to confirm whether or not T _m1s + T _m2s > T _mm is satisfied (this is a simple determination step). If the measurement accuracy is low, the pipe system identification method using the first determination step, the second determination step, and the third determination step may be performed.

  Thus, in the present invention, depending on the purpose, it is selected whether to perform the piping system etc. identifying method by the first determination step, the second determination step, and the third determination step or to perform the simple determination step. Is also possible.

  In addition, said 1st determination step, 2nd determination step, 3rd determination step, and said simple determination step in the piping system identification method of this invention can also be performed when a person performs calculation. However, it is of course possible to execute it by automatic calculation using computer software or hardware.

[Chirp wave]
In the piping system identification method and the piping system identification system of the present invention, it is preferable to use a chirp wave as the inspection signal. The chirp wave is a waveform whose frequency changes with time, for example, a time-stretched pulse wave (TSP wave). FIG. 7 shows a TSP wave whose frequency increases with time as an example of a chirp wave. Advantages of using the chirp wave as the inspection signal include that the inspection signal is more easily impulseed and the branch piping system is more easily identified.

  The identification of the branch piping system by the chirp wave will be described again with reference to FIG. When the chirp wave is received by the vibration receivers 12, 14, and 15 as signal receiving means, the received data is transmitted to the computer 20 and pulse compression processing is performed. This pulse compression processing is performed by impulseizing each received chirp wave.

  As an example, FIG. 8 shows a waveform obtained by pulsing the TSP wave shown in FIG. General sound waves such as hammering sound have a narrow band, so it is difficult to make an impulse even if pulse compression processing is performed, but a chirp wave has a wide band and can be impulsed. Since the impulse can be generated even if the S / N ratio of is low, it is suitable as the inspection sound wave used in the present invention.

  With respect to the impulsed data, each point (zero crossing) O where the impulse intensity intersects with zero is obtained, and the reception time of each chirp wave can be obtained from the zero crossing O. The reception time of each chirp wave may be obtained from a point (peak value) P at which the impulse intensity is maximum or a threshold passage point S at which the impulse intensity exceeds a certain threshold. Based on the reception time of these chirp waves, it is possible to calculate the signal arrival time at each part.

Simplified piping schematic diagram for explaining the piping system intended for the inner pipe Schematic piping diagram showing the inner pipe in which the piping system identification system of the present invention is installed The figure for determining the existence area | region of the meter M2 in which the piping system is not known in the 1st determination step of the piping system identification method of this invention. The figure for determining the existence area of meter M2 whose piping system is not known in the 2nd judgment step of the piping system identification method of the present invention. It is a model figure which shows schematically the difference of the piping system in an inner pipe, (a) shows the positional relationship of each site | part in case meter M1 and meter M2 are the same systems, (b) shows meter M1 Model showing the positional relationship of each part when meter and meter M2 are in separate systems The figure which shows the area | region of the conditions where the meter M1 and the meter M2 are the same systems in the 3rd determination step of the piping system identification method of this invention. The figure which shows the TSP wave which the frequency which is an example of a chirp wave increases in time The figure which shows the waveform which made the TSP wave shown in FIG. 7 an impulse

Explanation of symbols

1 Main piping 2 Service cock 3 Branch piping M1 Meter with known piping system M2 Meter with unknown piping system

Claims (9)

From a pipe system including a main pipe and a plurality of branch pipes connected to the main pipe via connection parts, the first part and the second part provided on the plurality of branch pipes are the same or different branches. A piping system identification method for identifying belonging to a piping system,
Of the three parts consisting of the first part, the second part, and the connection part, one part is used as a transmission part and the other part is used as a reception part. A measurement step for measuring the signal arrival time until it is received at the receiving site;
A piping system identification method comprising: a determination step of determining a difference between branch pipes to which the first part and the second part belong based on the signal arrival time measured in the measurement step.   The piping system identification method according to claim 1, wherein in the measurement step, the first part or the second part is used as the transmission part.   As the determination step, among the signal arrival times, the first signal arrival time between the first part and the connection part is more than the third signal arrival time between the first part and the second part. 3. The piping system identification method according to claim 2, wherein a first determination step of determining that the branch piping to which the first part and the second part belong is the same system is performed.   As the determination step, when the second signal arrival time between the second part and the connection part is larger than the third signal arrival time among the signal arrival times, the first part and the first part The piping system identification method according to claim 2 or 3, wherein a second determination step of determining that the branch piping to which the two parts belong is the same system.   As the determination step, the transmission part is changed in the measurement step, and signal arrival times between the three parts are respectively measured. Among the signal arrival times, the first signal arrival time and the second signal are measured. The third determination step of determining that the branch pipe to which the first part and the second part belong is the same system when the sum of the arrival times is larger than the third signal arrival time. 5. The piping system identification method according to any one of 4 above. As the determination step,
Among the signal arrival times, when the first signal arrival time between the first part and the connection part is larger than the third signal arrival time between the first part and the second part, A first determination step of determining that the branch pipe to which the first part and the second part belong is the same system;
The branch to which the first part and the second part belong when the second signal arrival time between the second part and the connection part is larger than the third signal arrival time among the signal arrival times A second determination step for determining that the pipe is of the same system;
In the measurement step, the transmission part is changed to measure the signal arrival time between the three parts, and the sum of the first signal arrival time and the second signal arrival time among the signal arrival times is 3. The piping system according to claim 2, wherein a third determination step of determining that the branch piping to which the first part and the second part belong is the same system when the third signal arrival time is longer than the third signal arrival time. Identification method. Performing the first determination step and the second determination step before the third determination step;
When the third determination step is such that the sum of the first signal arrival time and the second signal arrival time is larger than the third signal arrival time and smaller than twice the third signal arrival time, The piping system identification method according to claim 6, which is a step of determining that the branch piping to which the first part and the second part belong is the same system.   When the determination step executes the first determination step, the second determination step, and the third determination step, it is not determined that the branch pipe to which the first portion and the second portion belong is in the same system. The piping system identification method according to claim 6 or 7, which is a step of determining that the branch pipe is a separate system.   The piping system identification method according to claim 1, wherein the inspection signal includes a chirp wave.

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