JPH0861945A - Acoustic pipeline length measuring system and temperature correcting device therefor - Google Patents

Abstract

PURPOSE: To measure pipeline length in a short time and accurately even when a temperature difference exists between gas temperature in a pipeline and a measuring apparatus body by installing a temperature correcting device to correct reference temperature, depending on temperature in the pipeline. CONSTITUTION: The temperature correcting device 31 switches a mode selector switch S' to temperature correction mode (at memory 30) side and outputs a corrected temperature signal from a temperature correction circuit 33 at the time of correcting temperature, depending on difference between a signal from a sensor 27 within a measuring instrument body and a signal from a sensor 32 for correcting temperature. A memory 30 stores acoustic value data regarding gas (air, natural gas or the like) within a length measurement pipeline 28, and a switch is switched over, depending on the temperature and type of measured gas, on the basis of a signal regarding gas temperature corrected with a signal from the circuit 33, and an acoustic velocity value as reference for measuring pipeline length is set in CPU 22, depending on an acoustic velocity change due to the temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic pipe length measuring system for measuring the length of a pipe such as a buried pipe by using sound waves, and the temperature and composition of gas inside the pipe to be measured. The present invention relates to a sound velocity calibrating device that calibrates changes in sound velocity due to factors such as.

[0002]

2. Description of the Related Art A pipe such as a gas pipe buried in the ground may be corroded or damaged by an external force when laid for a long period of time. In such cases,
In order to facilitate repair work, a method is used in which the inner surface of the pipe is lined with a liquid resin or the like without being excavated and the pipe is repaired.

In the construction of this construction method, if the amount of resin introduced from the outside of the pipe is large relative to the length of the repair pipe, the resin is wasted, and if the amount of resin is small, the lining is insufficient. become. Therefore, it is necessary to accurately measure the length of the buried pipe to be repaired when performing this repairing method.

As the above-mentioned measuring means, an acoustic pipe length measuring system as shown in FIG. 1 has been conventionally developed. This example shows the case of measuring the pipeline length of the service pipe 28 drawn from the main pipe 29 buried in the ground under the road to the customer. The end of the pipe line) extends to the ground and the gas meter 15 attached to the upper end of the pipe line is removed to attach the connection body 1 of the sound wave length measuring instrument 21 to the ground opening of the length measurement pipe line 28.

FIG. 2 is an explanatory view showing the details of the sound wave length measuring device 21 and the main body 1. Screw 1 at the aboveground opening of the measuring pipe 28
The main body 1 fixed by screwing 6a into the main body 1 has a connecting portion, an open portion, and a bend between the sounding means 25 for sending a pulsed sound wave into the pipe of the length measuring pipe 28 and the length measuring pipe 28. Sound collecting means 26 for collecting pulsed sound waves reflected by a section or the like is provided. The sound wave length measuring device 21 has a CPU 2 inside.
2, a memory 24, a display 23, a D / A converter 19, an amplifier 17, an amplifier 18, and an A / D converter 20.
The sounding means 25 is D / based on a command from the CPU 22.
The A converter 19 converts the signal into an analog signal, and the pulsed sound wave signal amplified by the amplifier 17 sends out a pulsed sound wave inside the length measuring conduit 28. On the other hand, the sound collecting means 26 collects the pulsed sound waves reflected by the connecting portion, the open portion, the bend portion, etc. of the length measuring pipe 28, inputs them to the amplifier 18, and after amplifying them, the A / D converter 20. Convert it into a digital signal, and then CPU2
Enter 2. The CPU 22 measures the time from the generation of the sound wave to the reception of the sound wave by the internal aging circuit, converts it into the conduit length, and displays it on the display 23. The memory 24 stores the sound velocity value data of gas (air, natural gas, etc.) in the length measuring pipe 28, and the temperature at the time of measurement is measured by a temperature sensor (thermistor) as a temperature measuring means and is used as a reference. The temperature is set as a temperature, and the switch S is switched depending on the type and temperature of the gas to be measured, and a reference sound velocity value is set in accordance with the change in the sound velocity due to the type and temperature of the gas.

According to this acoustic pipe length measuring system,
The sound waves generate a connection, an open portion,
Since the reflected waves return from the bend part, etc., are characteristic of each, the length measurement pipe 2 is calculated from the product of the speed of sound and the time until the reflected waves return.
The distances to the connection part, the open part, and the bend part of No. 8 can be grasped in the buried state.

[0007]

By the way, in order to obtain an accurate pipe length, it is necessary to know the sound velocity in the pipe accurately. As is well known, the sound velocity in the pipe is It greatly changes depending on the gas temperature and gas components inside. Therefore, in the case of obtaining the pipeline length by the conventional acoustic pipeline length measuring system, in the case of the buried gas pipe for city gas, it is 0 for each type of gas under the same pressure as in the pipeline. The sound velocity at a temperature of ℃ to 30 ℃ is measured in increments of 1 to a few ℃ in advance, the mathematical expression showing the correlation between the sonic speed and the temperature, and the gas component is obtained, and the gas temperature is measured at the time of actual measurement. The measured value had to be corrected and calculated based on the temperature.

Therefore, in the measurement, it is necessary to measure the temperature of the gas, operate the switch S, etc., and the measurement operation is complicated, and it is difficult to maintain accuracy due to the occurrence of measurement error. It was

In order to solve the above-mentioned problems, the present applicant has proposed an acoustic pipe length measuring system (Japanese Patent Application No. 5-39532) equipped with a sound velocity calibration pipe. This system will be described below with reference to FIG.

In the figure, an acoustic pipe length measuring system equipped with the sonic velocity calibration pipe has a sounding means 2 for transmitting a pulsed sound wave from one end of the length measuring pipe 28 into the length measuring pipe 28.
5 and the length measuring pipe 2 at one end of the length measuring pipe 28.
From the sound collecting means 26 for collecting the pulsed sound wave reflected at the other end of 8, the time from the transmission of the pulsed sound wave to the collection of the sound wave, and the sound velocity value in the length measurement conduit 28. Length measuring line 2
8 is an acoustic pipe length measuring system including a measuring device for measuring the pipe length of 8, and the length is detachably provided in advance between one end of the length measuring pipe 28 and the length measuring system. The measured sonic calibration pipe 10 is wound around the coil and has a constant length, and the purge valve 14 is temporarily opened so that the sonic calibration pipe 10 has a length measuring pipe 28. Gas is introduced and filled, and the length of the conduit is calculated as [(Time until the reflected wave returning from the measurement point returns) / (Time until the first reflected wave returns) x (Sound velocity calibration pipe length)]-( Sound length calibration pipe length).

According to the invention of the above-mentioned application, when measuring the pipe length, the sonic calibration pipe 10 having a constant length, the length of which is measured in advance, is provided between the measuring system and the length measuring pipe 28. The gas in the length-measuring pipe 28 is introduced and filled in the sonic velocity calibration pipe 10, which is connected to the inside of the pipe 28 so as to communicate therewith. In this state, if the measurement work is performed in the same way as in the past,
The first reflected wave to be measured is the reflected wave that is reflected back by the connection between the one end of the length-measuring pipe 28 and the sonic velocity calibration pipe 10, and therefore returns to the sonic velocity calibration pipe 1 that is accurately known in advance.
It can be seen that the speed of sound in the gas with respect to the length of 0 is (the length of the sound velocity calibration pipe 10 × 2) ÷ (the round-trip time until the first reflected wave returns).

Since this sonic velocity is the sonic velocity in the gas inside the length-measuring pipe 28, it is not necessary to correct it by changes in gas components, temperature, pressure and the like. Therefore, if the measurement is performed by the sound wave as it is, the length of the length measurement conduit 28 can be accurately measured. Furthermore, the length of the length-measuring pipe 28 is actually [(the time until the reflected wave returning from the measurement point returns) / (the time until the first reflected wave returns) × (, regardless of the speed of sound in the gas itself. The length of the sonic velocity calibration pipe 10)]-(the length of the sonic velocity calibration pipe 10) is clear. Therefore, at the time of measurement, the temperature, pressure, and gas of the gas in the measuring pipe 28, which is the object to be measured, are measured. There is no need to consider components and other unknown error factors.

However, as a result of intensive research conducted by the present inventors after the application of the above invention, the following problems have been clarified regarding the conventional acoustic pipe length measuring system and the above-mentioned invention that has already been proposed. .

The temperature of the gas in the length-measuring pipe 28 is measured by the temperature sensor 27 in the main body 1 connected to the length-measuring pipe 28, which is used as a reference temperature. When the difference from the temperature of the main body 1 immediately before is large, the main body 1 (when the sonic velocity calibration pipe 10 is provided,
Since the heat capacities of the main body 1 and the sonic calibration pipe 10) are considerably larger than the heat capacities of the same volume of gas, the main body 1 (when the sonic calibration pipe 10 is provided, the main body 1 and the sonic calibration pipe 10) after the purging is started. Since it takes time (several minutes to several tens of minutes) until the temperature of (1) becomes equal to the temperature of the gas, the same degree of time is required for accurate temperature measurement by the temperature sensor. Therefore, the process of measuring the temperature of the gas reduces the work efficiency of the entire pipe length measurement work. One method of solving this is to increase the amount of purging per unit time, and to adjust the amount of gas contacting the main body 1 (the main body 1 and the sonic speed calibration pipe 10 when the sonic speed calibration pipe 10 is included) per unit time. However, due to the structural restriction that the purging valve 14 is provided in the main body 1, the purging valve 1 can be provided without increasing the heat capacity of the main body 1.
It is difficult to increase the opening area of No. 4. Further, since the purging is performed for a long time as described above, a large amount of gas is released into the air, which is uneconomical and may have an influence on the environment.

The present invention is intended to solve the problems of the conventional acoustic pipe length measuring system as described above and the invention already proposed by the present inventors.
When measuring the length of a pipe using an acoustic pipe length measuring system, if there is a difference between the temperature of the gas in the measuring pipe, which is the object to be measured, and the temperature of the measuring instrument body. Another object of the present invention is to provide an acoustic pipe length measuring system capable of directly measuring a pipe length accurately by eliminating a measurement error, suppressing wasteful discharge of gas in the pipe in a short time.

[0016]

The first means of the present invention for attaining this object is a sounding means for transmitting a pulsed sound wave from one end of a conduit to the inside of the conduit, and one end of the conduit. In sound collecting means for collecting pulsed sound waves reflected at the other end of the pipe, temperature measuring means for measuring reference temperature, and sound velocity value calculated from the reference temperature, and the pulsed sound waves are transmitted. In an acoustic pipe length measuring system including a length measuring unit that measures the pipe length from the time from the sound collection to the sound velocity value and the sound velocity value, the reference temperature is set according to the temperature in the pipe. It is characterized by having a tone correction means for correcting.

The second means is a sounding means for sending a pulsed sound wave into the conduit from one end of the conduit, and a pulsed sound wave reflected at the other end of the conduit at one end of the conduit. A sound collecting means for collecting sound, a temperature measuring means for measuring a reference temperature, a sound velocity value calculated from the reference temperature, a time from the pulsed sound wave being transmitted to the sound collection, and the sound velocity value. In an acoustic pipe length measuring system including a length measuring unit for measuring the pipe length from the above, the acoustic pipe length measuring system has a soundness correcting unit for correcting the reference temperature according to the temperature in the pipe. Characterized by the temperature compensator of the acoustic line length measuring system.

[0018]

According to the present invention, the gas inside the length measuring pipe is purged, and at the same time, the temperature sensor for correction is inserted into the length measuring pipe to directly measure the temperature of the gas. The correction mode selection switch S1 in the temperature correction device 31 can select the correction mode or the normal mode according to the measured gas temperature. Therefore, when the correction mode is selected, the signal corrected for temperature from the temperature correction circuit is selected. Is output. Due to such an action, when measuring the length of the pipe using the acoustic pipe length measuring system, the temperature between the gas in the measuring pipe, which is the object to be measured, and the temperature of the measuring instrument is measured. Even if there is a difference, the measurement error can be eliminated, the wasteful discharge of gas in the pipeline can be suppressed, and the pipeline length can be directly measured accurately in a short time.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments and respective embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 shows a first embodiment of the present invention.
1 is a schematic diagram of an acoustic line length measuring system with a temperature compensator 31. A screw 16a is provided at the above-ground opening of the measuring pipe 28.
A sounding means 25 for sending a pulsed sound wave into the pipe of the length-measuring pipe 28 is provided in the connection body 16 fixed via the.
And a sound collecting means 26 for collecting pulsed sound waves reflected by the connecting portion, open portion, bend portion, etc. of the length measuring pipe 28, and a temperature sensor 27 as a temperature measuring means.
The sound wave length measuring device 21 has at least a CPU 22,
Memory 30, display 23, D / A converter 19, amplifier 1
7, an amplifier 18, and an A / D converter 20. The temperature correction device 31 has a correction temperature sensor 32 as a correction temperature measuring means, a temperature correction circuit 33, and a mode selection switch S ′.

As the sound producing means 25 of the present invention, a speaker connected to an oscillator, a vibrating body having a piezoelectric element, or the like can be used, and as the sound collecting means 26, a known microphone or the like can be used. Further, the amplifier 17, the amplifier 18, the D / A converter 19, the A / D converter 20, the CP
Known electronic elements or electronic circuits can be used as the U22 and the memory 30, respectively.

The display 23 of the present invention includes a CRT (cathode ray tube) monitor, an LED (light emitting diode) display panel,
LC (liquid crystal) display, plasma display, E
An L (electroluminescent lamp) display or the like can be used.

In the temperature correction device 31, the mode selection switch S'opens and closes according to the difference between the signal from the temperature sensor 27 in the main body 1 and the signal from the correction temperature sensor 32, and the temperature correction circuit 33 causes the temperature to be changed. Can be a system that outputs a corrected signal, but apart from this,
A temperature correction circuit 33 having a volume or potentiometer or the like according to the measurement result of the correction temperature sensor 32.
May be a system directly operated by the measurer. In either case, the mode selection switch S'can select either the normal mode or the temperature correction mode. In the normal mode, the system is the same as the conventional system, and in the temperature correction mode, the signal from the correction temperature sensor 32 is used. The signal corrected accordingly is output from the temperature correction circuit 33 and input to the sound wave length measuring device 21.

As the temperature sensor of the present invention, one that operates at around room temperature can be used. For example, a thermistor (Thermistor = Thermally Se)
(native Resistor), thermocouple, resistance temperature detector (resistance temperature detection element), radiation type temperature detection sensor,
A bimetal, a thermal switch, a crystal temperature sensor, a liquid expansion type temperature sensor, an optical fiber distribution type temperature sensor, etc. can be used.

Specifically, as the thermistor, any one of a bead type, a disk type, a washer type, a pipe type, a chip type, and a flake type can be used, and an NTC having a negative temperature coefficient and a positive type can be used. PT with temperature coefficient of
Any of C and CTR having a negative temperature coefficient and a large change in resistance value can be used.

Either a sheath type or a consumable type can be used as the thermocouple, and the material is T type (copper-constantan), J type (iron-constantan), E type (chromel-constantan), K type ( Chromel-
Alumel), R type (platinum rhodium-platinum), S type (platinum rhodium-platinum), N type (platinel alloy), silver-gold type, and silver-palladium type can be used.

As the material of the resistance temperature detector, any of platinum, nickel, indium and tungsten-rhenium can be used.

The radiation type temperature detecting sensor may be either a monochromatic type or a bicolor type, and the monochromatic type material may be PbS, PbSe, p-type InSb or the like, and a bicolor type. The material of Si is PbSe,
PbS, InSb, etc. can be used.

The above bimetal can be used in the temperature compensator 31 as a bimetal type thermostat, and can be used as a thermostat of any of a laminated slow action contact type, a laminated snap action contact type, a snap disk type and a bimetal conducting type. Can be used.

The sound wave transmitted by the sounding means 25 of the present invention is
Any of audible sound waves and non-audible sound waves (ultrasonic waves) can be used. However, when a high frequency is used, the rate of sound wave attenuation increases, so that measurement becomes difficult when the length measuring pipe is long, and when the diameter of the length measuring pipe 28 is small or when the bend portion is used. When there is a joint pipe such as cheese or elbow, the reflection at that portion becomes large, and it is difficult to distinguish it from the reflected wave related to the pipe length to be measured. On the other hand, when a low frequency is used, the influence of noise becomes large and the measurement error becomes large. Therefore, it is preferably 50 Hz or more and 400 Hz or less, more preferably 200 Hz or more and 350 Hz or less, and optimally 250
It is preferable to set the frequency in the range of Hz to 310 Hz.

In this embodiment, first, one end of the length-measuring pipe 28 is opened for a short time to purge the natural gas therein, and at the same time, a temperature sensor 32 for correction is inserted into the length-measuring pipe 28 to directly measure the temperature of the gas. To measure. The measurer operates the potentiometer in the temperature correction circuit 33 according to the measured gas temperature. At this time, the mode selection switch S'in the temperature correction device 31 is manually operated in the correction mode (temperature correction circuit 3
3), the signal about the temperature corrected by the temperature correction circuit 33 serves as a reference when referring to the memory 30.

Next, the main body 1 is fixed to the open end of the length-measuring conduit 28 with the screw 16a. The speaker as the sounding means 25 is pulse-shaped inside the length-measuring conduit 28 by the pulse sound wave signal amplified by the amplifier 17 after being converted into an analog signal by the D / A converter 19 based on a command from the CPU 22. A sound wave (frequency 310 Hz) is transmitted. on the other hand,
The microphone as the sound collecting means 26 has a length measuring pipe 28.
The pulsed sound waves reflected by the connection part, the open part, the bend part, etc. are collected and input to the amplifier 18, and the amplified sound wave signal is converted into a digital signal by the A / D converter 20 and the CPU 22
Is input to

The CPU 22 measures the time from the generation of a sound wave to the reception of the sound wave by an internal time-lapse circuit (not shown), converts it into a conduit length, and displays it on a liquid crystal display as a display unit 23. The memory 30 stores the sound velocity value data of the gas (air, natural gas, etc.) in the length measuring pipe 28, and based on the signal related to the gas temperature corrected based on the signal from the temperature correction circuit 33. The switch S is switched according to the temperature, type, etc. of the gas to be measured, and the reference sound velocity value is set in correspondence with the change in the sound velocity due to the temperature or the like.

It should be noted that there is almost no difference between the gas temperature in the length measuring pipe 28 and the outside air temperature (that is, the temperature of the main body 1 immediately before the measurement), and the reference temperature does not need to be corrected within an allowable range. Is clear, the mode selection switch S '
Is set to the normal mode (connected to the temperature sensor 27 in the main body 1), and the same measurement as the conventional one can be performed.

According to this embodiment, in the acoustic pipe length measuring system, the pipe length can be accurately measured in a short time regardless of the temperature and type of gas.

[0036]

[Embodiment 2] In this embodiment, the gas in the length measuring pipe 28 is air. First, one end of the length measuring pipe 28 is opened for a short time, the gas (air) inside is purged, and at the same time, a thermistor as a temperature sensor 32 is inserted into the length measuring pipe 28 to directly measure the temperature of the gas (air). To do. The temperature correction circuit 33 outputs a signal related to the temperature according to the measured temperature of the gas (air). At this time, the temperature correction device 3
The mode selection switch S'in 1 has a difference between the temperature of the gas (air) measured by the temperature sensor 32 and the reference temperature indicated by the temperature sensor 27 in the main body 1 as necessary. In this case, since the correction mode is automatically set, the corrected temperature signal output from the temperature correction circuit 33 serves as a reference when referring to the memory 30.

Hereinafter, except that the frequency of the sound wave is set to 250 Hz, the measurement is carried out in the same procedure as in Example 1, so that the operation of the operator is reduced and the gas temperature, The pipe length can be accurately measured regardless of the type.

[0038]

[Third Embodiment] FIG. 5 shows a third embodiment of the present invention.
1 is a schematic view of an acoustic pipe length measuring system including a sound velocity correction pipe 10 and a temperature correction device 31. The sonic velocity calibration pipe 10 has a connector 12 provided at its tip, and a detachable handle 1
3 is connected to the end of the length-measuring pipe 28 (serving pipe).
The main body 1 provided with the sound collecting means 26 and the purge valve 14 that is manually opened and closed is fixed. The sound producing means 25 and the sound collecting means 26 are connected to the sound wave length measuring device 3 as in the conventional case.

The sound velocity calibration pipe 10 has a constant accurate length,
For example, a length of 3 m to 10 m is required, and any shape may be used as long as it does not reflect sound waves on the way,
Considering the convenience of the measurement work, it is preferable to wind it in a coil shape as shown in FIG. Sound velocity calibration pipe 10 and body 1
The connection with may be fixed as shown in Fig. 5, but like the tip, a connector with a handle is provided at the connection,
It may be detachable.

The temperature correction device 31 includes a correction temperature sensor 32 as a correction temperature measuring means, a temperature correction circuit 33,
It has a mode selection switch S ′. Temperature correction device 31
Is a system in which the mode selection switch S ′ is opened and closed according to the difference between the signal from the temperature sensor 27 in the main body 1 and the signal from the correction temperature sensor 32, and the temperature correction circuit 33 outputs a correction signal for temperature. It is supposed to be. In this case, since the mode selection switch S ′ can select either the normal mode or the temperature correction mode, the system is the same as the invention already filed in the normal mode, and the signal from the correction temperature sensor 32 is used in the temperature correction mode. The signal input to the sound wave length measuring device 21 is corrected accordingly.

FIG. 6 shows an acoustic wave length measuring device 3 and a temperature correcting device 3.
1 is a circuit diagram of FIG. 1, in which a sound wave length measuring device 3 is substantially the same as a conventional one, and at least a CPU 22 and a memory 3
0, a display 23, a D / A converter 19, an amplifier 17, an amplifier 18, and an A / D converter 20.

In this embodiment, first, one end of the length-measuring pipe 28 is opened for a short period of time to purge the internal air and at the same time, a thermistor as a temperature sensor 32 is inserted into the length-measuring pipe 28 to directly measure the temperature of the gas. To measure. The temperature correction circuit 33 outputs a temperature-corrected signal according to the measured gas temperature. At this time, the mode selection switch S ′ in the temperature correction device 31 is operated as needed (that is, between the gas temperature measured by the correction temperature sensor 32 and the temperature indicated by the temperature sensor 27 in the main body 1). Since the correction mode is automatically set, the signal from the temperature correction circuit 33 becomes the information about the temperature.

Next, the tip of the sound velocity calibration pipe 10 is connected to the length measuring pipe 28 by the connector 12, and the purge valve 14 is connected.
The gas inside the measuring pipe 28 by opening the sonic calibration pipe 10
Introduce the air into the sonic calibration pipe 10 sufficiently, and when the gas in the sonic calibration pipe 10 is replaced and filled, the purging valve is closed. At this time, the sound velocity calibration pipe 1
Since the gas in 0 is the same type and the same pressure as the gas in the length-measuring pipe 28, the sound velocity in the sound velocity calibration pipe 10 is the same as the sound velocity in the length-measuring pipe 28 except at least the temperature. It becomes a condition.

The sounding means 25 becomes an analog signal by the D / A converter 19 based on a command from the CPU 22, and the pulse sound wave signal amplified by the amplifier 17 causes a pulse shape inside the sound velocity calibration pipe 10 and the length measuring pipe line 28. The sound wave of is transmitted. On the other hand, the sound collecting means 26 collects pulsed sound waves reflected by the connecting portion, open portion, bend portion, etc. of the sound velocity calibration pipe 10 and the length-measuring pipe 28, inputs them to the amplifier 18, and after amplifying them, A The digital signal is converted by the / D converter 20 and the CP
Input to U22. The CPU 22 measures the time from the generation of a sound wave to the reception of the sound wave by an internal time-lapse circuit (not shown), converts it into a conduit length, and displays it on the display 23.

The time until the first reflected wave is detected is stored in the memory 30 and used as a reference value for the calculation performed by the CPU 22. Here, if there is a difference between the temperature of the gas and the temperatures of the main body 1 and the sound velocity calibration pipe 10, the temperature correction circuit 33
The reference value is corrected based on the corrected temperature-related signal from The ratio between this reference value and the time until the reflected wave generated in the length measurement pipe 28 is detected is the length of the sound velocity calibration pipe 10 and the distance to the position in the length measurement pipe 28 where the reflection wave occurs. The distance to the position where the reflected wave is generated in the length-measuring pipe 28 can be easily calculated and can be changed depending on the type of gas, pressure, temperature, etc. in the length-measuring pipe 28. There is no need for the operator to make corrections regarding the speed of sound in the gas, a memory for storing sound speed data under various conditions is no longer necessary, and the temperature, type, pressure, etc. of the gas can be adjusted in a short time and with a smaller error. Therefore, the pipe length can be accurately measured.

The correction temperature sensor 32 is not limited to one, but a plurality of temperature sensors can be arranged and the average sound velocity or the sound velocity distribution is obtained from the measurement results. It is also possible to make corrections, for example.

As the correction temperature sensor 32, for example, an optical fiber distribution type temperature sensor is provided in the sound velocity calibration pipe 10, the temperature distribution in the pipe is measured, and the reference value is corrected according to the result. It goes without saying that the accuracy of measuring the pipe length is further improved.

[0048]

As described above, the present invention solves the problems of the conventional acoustic pipe length measuring system and the invention already proposed by the present inventors. When measuring the length of a pipe using an acoustic pipe length measuring system, if there is a difference between the temperature of the gas in the measuring pipe that is the object to be measured and the temperature of the main body of the measuring instrument. Moreover, it is possible to provide an acoustic pipe length measuring system that can directly measure the pipe length accurately by eliminating measurement error, suppressing wasteful discharge of gas in the pipe in a short time.

[Brief description of drawings]

FIG. 1 is a diagram showing a conventional acoustic pipe length measuring system in use.

FIG. 2 is an explanatory diagram of a conventional acoustic wave length measuring device.

FIG. 3 is a schematic view of an acoustic pipe length measuring system that the present inventors have already applied for.

FIG. 4 is an explanatory diagram of an acoustic pipe length measuring system according to first and second embodiments.

FIG. 5 is a schematic diagram of an acoustic pipe length measuring system according to a third embodiment.

FIG. 6 is a circuit diagram of a sound wave length measuring device and a temperature correcting device according to a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 main body 3 sound wave length measuring instrument 10 sound velocity calibration pipe 14 purge valve 16a screw 17, 18 amplifier 19 D / A converter 20 A / D converter 22 CPU 23 indicator 24, 30 memory 25 sounding means 26 sound collecting means 28 Supply pipe, measuring pipe 29 Main S switch S'Mode selection switch

Claims (6)

[Claims] 1. A sounding means for transmitting a pulsed sound wave into the conduit from one end of the conduit, and a sound collecting means for collecting the pulsed sound wave reflected at the other end of the conduit at one end of the conduit. Means, temperature measuring means for measuring a reference temperature, and calculating a sound velocity value from the reference temperature, and measuring the pipe length from the sound velocity value and the time from when the pulsed sound wave is transmitted until the sound is collected. In the acoustic pipe length measuring system including a length measuring unit, the acoustic pipe length measuring system is provided with a tone correcting unit that corrects the reference temperature according to the temperature in the pipe. . 2. The acoustic pipe length measuring system according to claim 1, wherein the temperature correction means includes at least a correction temperature measurement means, a temperature correction circuit, and a mode selection means. 3. The acoustic pipe length measuring system according to claim 1, wherein the temperature correcting means is connected between the temperature measuring means and the length measuring means. 4. The acoustic pipe length measurement according to claim 1, wherein the sound producing unit, the sound collecting unit and the temperature measuring unit are provided in a main body connected to one end of the pipe. system. 5. The frequency of the sound wave is 50 Hz or higher and 40.
The acoustic pipe length measuring system according to claim 1, which is 0 Hz or less. 6. A sounding means for sending a pulsed sound wave into the conduit from one end of the conduit, and a sound collector for collecting the pulsed sound wave reflected at the other end of the conduit at one end of the conduit. Sounding means, temperature measuring means for measuring a reference temperature, a sound velocity value measured from the reference temperature, and a pipe length from the sound velocity value and the time from when the pulsed sound wave is transmitted until the sound is collected. In an acoustic pipe length measuring system including a length measuring unit for measuring, an acoustic pipe length including a soundness correcting unit that corrects the reference temperature according to a temperature in the pipe. Measuring system temperature compensator.