JPH04115110A - Method for measuring length of underground pipe branched from common underground pipe for supplying gas - Google Patents

Abstract

PURPOSE:To make it possible to measure the length accurately even for complicated pipelines by computing the length of underground branched pipe based on the passing time of detecting gas through the underground branched pipe, the time for passing a detecting pipe by a specified distance, and the specified time. CONSTITUTION:A gas-meter cock 4 is opened, and detecting gas is filled in a supply pipe 2. Then, the gas 5 is in the filled state in the supply pipe 2. A part of the gas overflows through a service, tee 3 and flows into a main branch pipe 1. When the flow of supply gas 7 in the main branch pipe 1 is less, the overflowed gas 5 remains in the vicinity of the service tee 3. This becomes the cause of error in boundary measurement. When the gas 7 in the main branch pipe 1 is less, the gas 7 is made to flow out at a neighboring user house corresponding to another supply pipe 8 which is branched from the main branch pipe 1 at a position close to the supply pipe 2. Thus, the flow is generated. At this time, a boundary 9a is formed between the gas 5 on the side of the supply pipe 2 and the gas 7 on the side of the main branch pipe 1 at the part of the service tee 3.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for measuring the length of a branch buried pipe branched from a common buried gas supply pipe.

(Prior art) For example, in a city gas supply system, when repairing the inner surface of a supply pipe branched from a main branch pipe, which is a commonly buried pipe, it is necessary to measure its length. The length is measured on the ground using a tape measure by estimating the branch extraction position of the service tee, etc.

(Problems to be Solved by the Invention) Length measurement from the ground using a tape measure cannot measure complex piping systems that have curved parts such as cuts, and the length measurement is performed by estimating the extraction position, which may result in errors. is very large.

It is an object of the present invention to provide a length measuring method that can solve these conventional problems and accurately measure the length of even a complicated piping system.

(Means for Solving the Problems) In order to solve the above-mentioned problems, first, the length measuring method of the present invention includes a method for measuring a length of a branch buried pipe branched from a common buried pipe for gas supply.
The process of filling a detection gas that can be distinguished from the supply gas from the measuring end provided with a flow path opening/closing means, and the supply of the detection gas that has reached the common buried pipe from the branch buried pipe through the filling and flows through the common buried pipe. a process of moving the branch buried pipe with gas, connecting a detection tube with the same inner diameter to the length measurement end of the branch buried pipe via the flow path opening/closing means, and installing a first sensor corresponding to the length measurement end; , installing a second sensor in the detection tube at a predetermined distance from the first sensor, and causing the detection gas in the branch buried pipe to flow out through the detection tube, before and after that. The time for the detection gas to pass through the branch buried pipe and the time for it to pass a predetermined distance of the detection pipe are measured by the process of detecting passage of the boundary by the first and second sensors while measuring the time. and the ratio of these times,
The length of the branch buried pipe is calculated from the predetermined distance of the detection pipe.

Another length measuring method of the present invention is to fill a branch buried pipe branched from a common buried pipe for gas supply with a detection gas that can be distinguished from the supply gas and air from the length measurement end provided with a flow path opening/closing means. a step of moving the detection gas that has reached the common buried pipe from the branch buried pipe by filling with the supply gas flowing through the common buried pipe; and a step of installing the flow path opening/closing means at the measuring end of the branch buried pipe. connecting a detection tube with the same inner diameter through the detection tube, and installing a sensor in the detection tube at a predetermined distance from the length measuring end; The time taken for the detection gas to pass through the branch buried pipe and the time taken for the detection gas to pass a predetermined distance of the detection pipe is measured by the process of letting the gas flow out and detecting the passage of the boundary before and after it with the sensor while measuring the time. The length of the branch buried pipe is calculated from the ratio of these times and the predetermined distance of the detection pipe.

In the above method, the flow of the supply gas for moving the detection gas is such that the supply gas flows out from another branch buried pipe that branches from the common buried pipe at a position close to the branch buried pipe where measurement is performed. can be generated.

Further, it is preferable that the detection gas be discharged from the branch buried pipe by moving it in a laminar flow state.

Furthermore, in the above method, the pressure of the detection gas filled from the measurement end is set slightly higher than the pressure of the supply gas, and the amount is equal to the total volume of the branch buried pipe converted from the predicted length on the ground. It is good to set it to 1.5 times to 2 times.

Further, in the above method, the detection signal of the detection gas by the sensor is recorded on a recorder over time, and the time when the detection gas passes through the branch buried pipe and the time when the detection gas passes through a predetermined distance of the detection pipe are recorded. time can be measured.

Moreover, each of the above-mentioned sensors can be installed in the detection tube in advance.

(Function) By filling from the measuring end, the detection gas that has reached the common buried pipe from the branch buried pipe moves along the common buried pipe by the supply gas flowing through the common buried pipe, so that it does not reach the branch part. In this case, there is a clear boundary between the supply gas and the detection gas, and therefore the detection gas is filled only in the branch buried pipe, that is, only within the length measurement range.

In such a state, when the detection gas in the branch buried pipe is made to flow out through the detection tube, the front end boundary, that is, the boundary with the air, and the rear end side boundary, that is, the boundary with the supply gas, will flow. Boundaries also move.

The first sensor corresponding to the length measuring end of the branch buried pipe is in a state of detecting the detection gas on the front end side from the beginning of the outflow, and becomes a non-detecting state when the boundary on the rear end side passes over time.

Therefore, the elapsed time from the start of outflow until the first sensor enters the non-detection state corresponds to the time required for the boundary on the rear end side of the detection gas to move from the branch part to the length measurement end.

On the other hand, since the boundary on the rear end side that has passed through the first sensor passes through the second sensor portion after a predetermined period of time has passed, the second sensor is in a non-detecting state of the detection gas at this point. Therefore, the elapsed time from when the first sensor becomes non-detecting state to when the second sensor becomes non-detecting state is equivalent to the time required for the rear edge side boundary to move a predetermined distance of the detection tube. do.

By the way, the detection tube has the same inner diameter as the branch buried pipe, and the flow rate of the detection gas flowing in the detection tube is equal to the flow rate in the branch buried pipe, so the elapsed time is proportional to the length of the pipe no matter which tube it flows through. Therefore, since the ratio of the elapsed time corresponds to the ratio of the length of the branch buried pipe and the predetermined distance of the detection tube, the length of the branch buried pipe can be calculated from these ratios and the predetermined distance.

In the above operation, the flow of the supply gas for moving the detection gas is such that the supply gas flows out from another branch buried pipe that branches from the common buried pipe at a position close to the branch buried pipe where measurement is performed. This can be easily generated. Further, if the detection gas flows out from the branch buried pipe in a laminar flow state, the detection gas and the supply gas can maintain a clear boundary due to laminar flow movement. Furthermore, in the above method, if the pressure of the detection gas filled from the measurement end is set to a level slightly higher than the pressure of the supply gas, the test gas can be filled without fluctuations in the pressure of the supply gas in the common buried pipe. Filling can be done. Moreover, if the filling amount is 1.5 to 2 times the total volume of the branch buried pipe calculated from the predicted length on the ground, measurement errors due to insufficient amount can be prevented.

Further, in the above method, if the detection gas is distinguishable from the supply gas and air, and the second sensor is capable of detecting it, the second sensor is configured to detect the detection gas. Both the front end side and rear end side boundaries can be detected, and therefore both the elapsed times can be measured using only the second sensor, and the first sensor can be omitted.

(Example) Next, embodiments of the present invention will be described with reference to the drawings.

Figures 1 to 3 schematically represent an embodiment in which the present invention is applied to a buried pipe in a city gas supply system. It is a branch pipe. Reference numeral 2 is a branch buried pipe branched from this main branch pipe 1, that is, a supply pipe, and reference numeral 3 is a service pipe. Further, reference numeral 4 denotes a gas meter cock, and in this embodiment, this gas meter cock 4 is used as a channel opening/closing means at the length measuring end.

Therefore, when measuring the length of the supply pipe 2, a cylinder 6 or the like filled with the detection gas 5 is first connected to the gas meter cock 4. The inspection gas 5 is a single gas or a mixed gas that can be distinguished from the supply gas 7 as described later, and its pressure is set slightly higher than the supply gas pressure. Further, the detection gas can be distinguished from air as well as the supply gas, as will be described later.

Then, the gas meter cock 4 is opened and the detection gas 5 is opened.
When the supply pipe 2 is filled with the detection gas 5, the supply pipe 2 is filled with the detection gas 5, and a portion of the detection gas 5 overflows from the service channel 3 and flows into the main branch pipe 1.

The amount of detection gas 5 to be filled into the supply pipe 2 is, for example, about 1.5 to 2.0 times the total volume obtained by multiplying the estimated length of the supply pipe 2 on the ground by the pipe diameter. It is possible to prevent the actual filling amount from being insufficient or too large.

In the above operation, the supplied gas 7 at the nearby consumer
If the flow of the supply gas 7 in the main branch pipe 1 is small due to the small amount of gas used, the overflowing detection gas 5 will remain in the vicinity of the service channel 3 as described above, so boundary measurement, which will be described later, will be carried out. This becomes an error factor. Therefore, in the present invention, when the flow of the supply gas 7 in the text 'lrl is small, such a flow is actively generated. That is, in the embodiment, the supply gas 7 is caused to flow out at an adjacent consumer corresponding to another supply pipe 8 branched from the main branch pipe 1 at a position close to the supply pipe 2 to be measured. This causes the above flow to occur. Therefore, due to the above-mentioned filling, the supply pipe 2
The detection gas 5 that has reached the main branch pipe 1 is moved by the supply gas 7 and is separated from the vicinity of the service ch 3. Therefore, the detection gas 5 on the supply pipe 2 side is A clear boundary 9a between the main branch pipe 1 side and the supply gas 7
occurs.

Around the same time as the above operation, the gas meter cock 4:
Instead of the cylinder 6, a detection tube 10 having the same inner diameter as the supply tube 2 is connected. In the detection tube 10, a first sensor lla corresponding to the length measuring end and a second sensor llb are installed at a predetermined distance from the first sensor lla, and these sensors 11a, A measurement device H12 is installed to measure the detection signal of llb over time. Further, a diffusion tube 14 is connected to the end of the detection tube 10 via a cock 13 as required. The second sensor llb may be installed anywhere as long as the distance from the first sensor lla is known or can be easily measured. It is installed at the end of the Moreover, if these first and second sensors lla and llb are installed in the detection tube 10 in advance, installation is easy. And these sensors lla, 11. In addition to analog output type, b is ON-○
An FF output type can be applied. Also, the measuring device 12
are each sensor lla, 11. An appropriate measuring device such as a recorder can be used as long as the detection signal obtained by b can be measured over time.

In the above state, the gas meter cock 4 is opened, and the cock 1 provided between the detection tube 10 and the diffusion tube 14 is opened.
3 is opened, the detection gas 5 in the supply tube 2 is moved by the pressure of the supply gas 7, and the detection tube 10 and the diffusion tube 14 are moved.
It flows out through the air and dissipates into the atmosphere. As the detection gas 5 flows, its front end boundary, ie, the boundary 9b with air, and its rear end boundary, ie, any boundary 9a of the supply gas 7, move.

At this time, the first sensor l corresponding to the length measurement end of the supply v2
la detects the detection gas 5 on the front end side from the start of outflow, and this detection state continues until the boundary 9a on the rear end side passes. Therefore, the elapsed time T1 during this period corresponds to the time required for the boundary 9a on the rear end side of the detection gas 5 to move from the service channel 3, which is the branch point with the main branch pipe 1, to the measuring end of the supply pipe 2. . On the other hand, the first sensor lla
The boundary 9a on the rear end side, which has passed through, passes through the second sensor 1],b portion after a predetermined time has elapsed, so the second sensor Ilb is in a non-detecting state of the detection gas 5 at this point. Therefore, the elapsed time T from when the first sensor Ila becomes non-detecting state to when the second sensor [1b] becomes non-detecting state is such that the rear end side boundary 9a is the detection tube. Detection tube 1 of a predetermined distance, in this case length, of 10
This corresponds to the time required to move 0. Also, these elapsed times T, , T.

The detection signals of the sensors lla and llb described above can be measured by a measuring device 12 such as a recorder, for example, as shown in FIG. 4(a).

Therefore, if the length of the supply pipe 2 to be measured is Ll, then L:L, ==T, :T holds true, so each of these elapsed times T, , T, is calculated by each sensor lla described above.
, 11. b and is measured by a measuring device 12 such as a recorder, and the length Ll of the supply pipe 2 can be calculated from the following equation.

L = L, (T /T, ) Note that the measurement results shown in Figure 4 (a) are based on the second sensor l.
lb can distinguish the detection gas 5 only from the supply gas 7,
This indicates a case where the gas cannot be distinguished from air; in this case, the second sensor Ilb can detect the boundary 9a at the rear end of the detection gas 5, but cannot detect the boundary 9b at the front end. Therefore, as mentioned above, the first sensor lla is essential.

However, for example, as the detection gas 5, the supply gas 7
and a gas that can be distinguished from air, and if the second sensor llb can identify these, the second llb
can also detect the boundary 9b at the front end of the detection gas 5, so for example, as shown in FIG. 4(b) or (C), the elapsed time T, ,
T, and therefore in these cases the first sensors lla, llb can be omitted. Note that (a) shows an example in which an ON-OFF output type sensor is used, and (b) shows an example in which an analog 8-force type sensor is used.

Incidentally, if the outflow of the detection gas 5 from the above-mentioned supply pipe 2 via the detection tube 10 is performed by moving the detection gas 5, supply gas 7, and air in a laminar flow due to natural dissipation into the atmosphere, etc.,
Clear boundaries 9a and 9b can be maintained, and measurement accuracy can be maintained.

Further, as described above, the detection gas 5 and the sensor ll
a, llb, if the detection gas 5 can be detected by distinguishing it from the supply gas 7 or by distinguishing it from air together with the supply gas 7, an appropriate single gas or mixed gas and a sensor thereof can be used. can do. For example, when the present invention is applied to a city gas supply system as shown in the above embodiment, the detection gas 5 and its sensor can be as shown below.

[Example 1] Mixed gas of methane + propane + oxygen This detection gas 5 contains the above components, for example, 75.20%.
The detection gas 5 is mixed at a mixing ratio of about 5% by volume, and is distinguished from the supply gas 7 by the presence or absence of oxygen. Therefore, sensor 11a.

11b can be constituted by an oxygen sensor, and the device is simple and can perform highly accurate detection. In addition, such a sensor 1
1. If analog output type sensors capable of detecting oxygen concentration are used as a and llb, these sensors lla,
For example, as shown in FIG. 4(c), the detection gas 5 can be detected by distinguishing it from air together with the supply gas 7.

Therefore, in this case, as described above, the first sensor 11a
can be omitted.

[Example 2 Mixed gas of comethane + propane + oxygen + hydrogen This detection gas 5 contains, for example, 75.21.2.2% by volume of the above components.
The detection gas 5 is distinguished from the supply gas 7 by the presence or absence of hydrogen.

Therefore, the detector 11 can be constituted by a hydrogen sensor, which can also perform highly accurate detection. Also, in this case, the sensors lla and llb can detect the detection gas 5 together with the supply gas 7 by identifying it as air, as shown in FIG. The first sensor lla can be omitted.

In addition, non-combustible components such as carbon dioxide gas may be mixed in place of the combustible components of the mixed gas described above, and the supply gas 7 may be identified by the presence or absence of this non-combustible component, or the supply gas 7 itself may contain fluorocarbon gas, etc. It is possible to mix gases that are not included and identify the presence or absence of this gas. Furthermore, in the above embodiments, the detection gas 5 itself has components for identification, but conversely, the detection gas 5 is mixed with the components contained in the supply gas 7. First, it is also possible to perform identification based on the presence or absence of this component. For example, if a supply gas not mixed with an odorant is used as the detection gas 5 in contrast to a supply gas 7 mixed with an odorant, identification can be made based on the presence or absence of the odorant. Furthermore, if pure methane is used as the detection gas 5 for the supply gas 7 containing components other than methane, it is possible to identify the supply gas 7 based on the presence or absence of components other than methane.

In addition to the above-described embodiments, the detection gas 5 may be any suitable gas that can be detected separately from the supply gas 7 or together with the supply gas 7 as air.

(Effects of the Invention) As described above, the present invention fills the detection gas only in the length measurement range of the branch buried pipe branched from the common buried pipe for gas supply, and the detection gas in the branch buried pipe. The detection gas is caused to flow out through a detection tube whose predetermined length is known or can be easily measured, and the time taken for this detection gas to pass through a branch buried pipe, the time for it to pass a predetermined distance of the detection tube, and this predetermined distance. Since the length of branch buried pipes is calculated, it is possible to accurately measure the length of even complex piping systems with bends such as cuts.For example, in city gas supply systems, live pipes This has the effect of being able to measure the length easily and in a short time.

[Brief explanation of drawings]

1 to 3 are explanatory sectional views showing the configuration and operation of an embodiment to which the present invention is applied, and FIGS. 4(a), (b), and (c)
) is an explanatory diagram showing an example of a measurement result. Code 1... Main branch pipe (common buried pipe), 2... Supply pipe (
Branch buried pipe), 3... Service Q, 4... Gas meter cock (channel opening/closing means), 5... Detection gas, 6
... Cylinder, 7... Supply gas, 8... Other supply pipes, 9a, 9b-boundary, 10-... Detection tube, Ila, 1.
1b...detector, 12...measuring device, 13...cock, 14...dispersion tube.

Claims (10)

[Claims] (1) The process of filling a branch buried pipe branched from a common buried pipe for gas supply with a detection gas that can be identified as the supply gas from the measuring end provided with a flow path opening/closing means, and the process of filling a branch buried pipe branched from a common buried pipe for gas supply with a detection gas that can be distinguished from the supply gas. A process in which the detection gas that has reached the buried pipe is moved by the supply gas flowing through the common buried pipe, and a detection pipe having the same inner diameter is connected to the length measuring end of the branch buried pipe via the flow path opening/closing means. , installing a first sensor corresponding to the length measurement end, and installing a second sensor at a location on the detection tube at a predetermined distance from the first sensor;
The detection gas in the branch buried pipe is caused to flow out through the detection pipe, and the passage of the boundary before and after the branch pipe is detected by the first and second sensors while being timed. The method is characterized in that the time for passing through the branch buried pipe and the time for passing through a predetermined distance of the detection tube are measured, and the length of the branch buried pipe is calculated from the ratio of these times and the predetermined distance of the detection tube. Method for measuring the length of a branch buried pipe branched from a common buried pipe for gas supply (2) A process of filling a branch buried pipe branched from a common buried pipe for gas supply with a detection gas that can be distinguished from the supply gas and air from the measuring end provided with a flow path opening/closing means, and a process of filling the branch buried pipe branched from the common buried pipe for gas supply, and filling the branch buried pipe with a detection gas that can be distinguished from the supply gas and air. A process in which the detection gas that has reached the common buried pipe is moved by the supply gas flowing through the common buried pipe, and a detection tube with the same inner diameter is connected to the measuring end of the branch buried pipe via the flow path opening/closing means. connecting and installing a sensor at a predetermined distance from the length measuring end of the detection tube, and flowing out the detection gas in the branch buried pipe through the detection tube, and establishing a boundary between the front and back. The time for the detection gas to pass through the branch buried pipe and the time for it to pass through a predetermined distance of the detection pipe are measured by the step of detecting the passage of the detection gas by the sensor while measuring the time, and the ratio of these times, A method for measuring the length of a branch buried pipe branched from a common buried pipe for gas supply, characterized in that the length of the branch buried pipe is calculated from the predetermined distance of the detection tube. (3) In the method of claim 1 or 2, the flow of the supply gas for moving the detection gas is connected to another branch buried pipe branched from the common buried pipe at a position close to the branch buried pipe where measurement is performed. A method for measuring the length of a branch buried pipe branched from a common buried gas supply pipe, characterized in that supply gas is generated by flowing out from the pipe. (4) In the method of claim 1 or 2, the detection gas flows out from the branch buried pipe in a laminar flow state, and the branch buried pipe branches from the common buried gas supply pipe. Length measurement method (5) In the method of claim 1 or 2, the pressure of the detection gas to be filled from the measurement end is set slightly higher than the pressure of the supply gas, and the amount is converted from the predicted length on the ground by branch burial. A method for measuring the length of a branch buried pipe branched from a common buried pipe for gas supply, characterized in that the length is 1.5 to 2 times the total volume of the pipe. (6) In the method of claim 1, the detection signals of the detection gas by the first and second sensors are recorded in a recorder over time, and the time taken for the detection gas to pass through the branch buried pipe is determined. A method for measuring the length of a branch buried pipe branched from a common buried pipe for gas supply, characterized by measuring the time it takes for the detection tube to pass a predetermined distance. (7) In the method of claim 2, the detection signal of the detection gas by the sensor is recorded on a recorder over time, and the time for the detection gas to pass through the branch buried pipe and the predetermined distance of the detection pipe are determined. A method for measuring the length of a branch buried pipe branched from a common buried pipe for gas supply, characterized by measuring the time it takes for the pipe to pass through the common buried pipe for gas supply. (8) The first and second sensors of claim 1 are a method for measuring the length of a branch buried pipe branched from a common buried gas supply pipe, characterized in that the first and second sensors are respectively installed in advance at both ends of the detection tube. (9) The sensor according to claim 2 is a method for measuring the length of a branch buried pipe branched from a common buried pipe for gas supply, characterized in that the sensor is installed in advance on the detection pipe. (10) In the length measurement method of claim 1, the detection gas is
A method for measuring the length of a branch buried pipe branched from a common buried pipe for gas supply, characterized in that it can be distinguished from supply gas and air.