JPH10160616A - Monitoring system for gas leakage from gas conduit - Google Patents

Abstract

(57) [Summary] [PROBLEMS] Among conventional methods for detecting gas leakage from a gas pipe such as a service pipe, boring is performed on the ground where the service pipe is buried, and a gas detector is used. The method of using or smelling the odor to confirm the presence or absence of leakage requires excavation work such as boring or the like, and it takes a lot of people. According to the present invention, in order to solve such a problem, a pressure sensor is provided in a gas meter so that a pressure can be measured together with a flow rate of a gas flowing through a gas conduit.
An initial value setting process in which the pressure is integrated for a set time when a gas having a flow rate equal to or more than a set flow rate is used due to use of the gas at a time when there is no leak in the gas conduit, and the integrated value and the flow rate are stored as initial values; When the same amount of gas flows as the initial value in the use of the pressure, the pressure is integrated over the set time, the integrated value is compared with the initial value, and if it is smaller than the initial value, a leak monitoring process is performed to determine gas leakage. We propose a gas leakage monitoring system composed of

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for monitoring gas leakage from a gas conduit.

[0002]

2. Description of the Related Art For example, a conventional method for detecting a leak from a main gas pipe of a city gas pipe system to a gas meter of a customer, that is, a leak of a supply pipe and an inner pipe (a service pipe) is known as a service pipe. Boring on the ground where is buried,
It is common to use a gas detector or smell the odor to check for leaks.

[0003]

However, such a conventional method requires an excavation work such as boring, and has a problem in that a large number of people are required. An object of the present invention is to solve such a problem.

[0004]

In order to solve the above-mentioned problems, in the present invention, a pressure sensor is provided in a gas meter so that the pressure can be measured together with the flow rate of the gas flowing through the gas conduit, and the gas leaks into the gas conduit. When there is no gas, the pressure is integrated for a set time when the gas flows over the set flow rate by using the gas, and the initial value setting process of storing the integrated value and the flow rate as initial values, and the initial value in the subsequent gas use When the same amount of gas flows, the pressure is integrated for the set time,
The present invention proposes a system for monitoring the leakage of gas from a gas pipe, comprising: a leak monitoring step of comparing an integrated value with an initial value and, when smaller than the initial value, determining that the gas leaks from the gas pipe.

According to the present invention, in the above configuration,
In the initial value setting process, a flow rate equal to or higher than the set flow rate is stored as an initial value, and at that time and thereafter,
By integrating the pressure when the gas of the flow rate flows for a set time, a plurality of pressure integrated values for the same flow rate are obtained,
It is proposed that their average value be used as the initial value of the pressure integral value.

According to the present invention, in the above-described configuration, in the leak monitoring step, first, the pressure is integrated for a set time every time the same amount of gas flows as the initial value, and the integrated value is compared with the initial value. A method is proposed for determining that gas has leaked when a state in which the initial value is not reached occurs continuously for a set number of times. In order to apply this method, in the present invention, in the leak monitoring process, each time the same amount of gas as the initial value flows, the pressure is integrated for a set time, and the integrated value is compared with the initial value. The state that does not reach is stored as history in the storage means,
Otherwise, the history of the storage means is cleared and monitoring is continued, and the number of times that the integral value does not reach the initial value is obtained from the history of the storage means. It is suggested to judge. In this method, the storage means may be configured to store only the number of times when the initial value is not reached, or may be configured to store data of the integrated value when the integrated value of the pressure does not reach the initial value. It is also possible to obtain the number of times that does not reach the initial value from the number of data obtained.

According to the present invention, in the above-described configuration, in the leak monitoring step, the pressure is integrated for a set time every time the same amount of gas flows as the initial value, and the integrated value is compared with the initial value to obtain an integrated value. In addition to extracting data in which the absolute value of the difference between the value and the initial value is smaller than the set value, extracting data whose integral value is smaller than the initial value from the extracted set number of data, and the number has reached the set number. In this case, a method for determining that the gas is leaking is proposed. In order to apply this method, in the present invention, in the leak monitoring process, the pressure is integrated for a set time at each time when the same amount of gas flows as the initial value, and the integrated value is compared with the initial value. The data whose absolute value of the difference is larger than the set value is discarded, and the other data is stored in the storage means. If the number of stored integrated values reaches the set number, the stored data is stored. It is proposed to compare each data with an initial value to determine the number of data that does not reach the initial value, and determine that the gas leaks when the number of data is larger than the set number.

In the above invention, the set of the gas flow rate and the integral value set as the initial value is basically one set, but a plurality of sets, that is, a plurality of flow rates and the integral values corresponding thereto are initially set. It can also be set as a value.

According to the present invention, since the gas meter can measure the pressure together with the flow rate of the gas, a decrease in pressure due to leakage from the gas conduit is detected by measuring the gas under the same flow rate. be able to. Since the detection of the pressure drop due to the leak is performed by comparing the integrated value obtained by integrating the pressure for a set time, a small vertical change in the gas supply pressure is averaged, and therefore, the decrease in the gas supply pressure is caused by the leak. It is possible to prevent erroneous determination as to be performed.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 conceptually shows an example of a gas pipe system to which the present invention is applied, which shows a pipe system of a city gas pipe system which is drawn into a customer from a main pipe. Reference numeral 1 denotes a main branch pipe, and reference numeral 2 denotes a service pipe, that is, a supply pipe from a main branch branch point to a road boundary of a conduit branched from the main pipe 1 and drawn into a customer, and a gas of a customer from a road boundary. It is a conduit including the inner tube up to the entrance of the stopper. Reference numeral 3 denotes a gas meter, 4 denotes a gas appliance, and the gas meter 3 is provided with a pressure sensor 5 built in or externally attached. In addition, the flow rate measuring unit in the gas meter 3 is represented by reference numeral 6. Reference numeral 7 denotes a monitoring device. The monitoring device applies the present invention with the flow signal from the flow measuring unit 6 of the gas meter 3 and the pressure signal from the pressure sensor 5 as inputs, and monitors the leakage from the service pipe 2. Configuration.

Next, the principle of the present invention will be described. FIG. 2 is an explanatory diagram showing a change in gas pressure along the service pipe 2 from the main pipe 1 to the gas meter 3. At this time, in the gas conduit system shown in FIG. 1, it is assumed that a leak occurs at a location L of the service pipe 2, a portion of the service pipe 2 from the main pipe 1 to the leak location L is A, and a gas meter 3 is located at the leak location L. Up to B
When the supply pressure of the gas from the main pipe 1 is Y, and the gas of the flow rate Q is flowing using the gas appliance 4,
Let the pressure losses of the portions A and B be a and b, respectively.

The solid line in FIG. 2 shows the change in pressure when gas is not used at the time when there is no leakage in the service pipe 2. When the flow rate is 0, there is no pressure loss due to the flow, so the pressure of the gas meter 3 The pressure of the gas measured by the sensor 5 is equal to the pressure Y of the main pipe 1. The dashed line in FIG. 2 indicates a change in pressure when gas having a flow rate Q is flowing by use of the gas appliance 4 at a time when there is no gas leakage from the service pipe 2. Since a pressure loss occurs in accordance with the gas flow rate, the pressure decreases linearly along the service pipe 2, and the gas pressure measured by the pressure sensor 5 of the gas meter 3 becomes Y−
(A + b). Next, the two-dot chain line in FIG.
This shows the pressure change when the gas of the flow rate Q is used in the gas appliance 4 in the state where there is a leakage of Qm from the above-mentioned location L. In the service pipe section A, the flow rate increases due to the leakage. The pressure loss increases, and at point L, Y-
a × (Q ² + Qm ² ) / Q ² . Therefore, the pressure difference from the case where there is no leakage is a × Qm ² / Q ² . This is derived based on the relationship that when the gas is at a low pressure, the pressure difference of the gas flowing through the pipe is proportional to the square of the flow rate. On the other hand, the flow rate of the gas in the service pipe section B is the flow rate Q as in the case where there is no leakage, so that the pressure loss is b as in the case of the dashed line, and is therefore measured by the pressure sensor 5 of the gas meter 3. The gas pressure is Y− [a × ｛(Q ² + Qm ² ) /
Q ² ｝ + b], and the difference from the pressure when there is no leakage is a × Q m ² / Q ² , similarly to the point L.

From the above, the gas pressure measured by the gas flow rate measuring unit 6 of the gas meter 3 is measured under the same flow rate, and the pressure drop is compared with the value measured when there is no leakage. By detecting, leakage from the service pipe 2 can be detected.

At this time, in the present invention, the detection of the pressure drop is not compared with the instantaneous value, but the pressure is integrated over a predetermined time and compared with the integrated value. Small up-and-down changes in the supply pressure of the gas are averaged out, so that it is possible to prevent such a decrease in the supply pressure of gas in a relatively short cycle from being erroneously determined to be due to leakage.

FIG. 3 is a flow chart conceptually showing the operation of the leak monitoring system to which the present invention is applied in the configuration of the gas conduit system described above. The monitoring device 7 first monitors the measured value of the flow rate measuring unit 6 of the gas meter 3 in step S1, and shifts to step S2 when there is a flow rate. That is, whether or not gas is used is monitored. If no gas is used and there is no output of the flow rate, the operation of step S1 is repeated to continue monitoring. In step S2, it is determined whether or not the flow rate is equal to or higher than a preset flow rate. If the flow rate has not reached the set flow rate, the process returns to step S1 to continue monitoring. If the flow rate is equal to or more than the set flow rate, the flow shifts to step S3 to store the flow rate in the storage means, and then shifts to step S4. In step S4, the measured value of the pressure sensor 5 of the gas meter 3 is integrated for a preset time, and in the next step S5, the integrated value is stored in the storage means. Due to this integration, small fluctuations in the gas supply pressure within the set time are averaged out. The initial value setting process A is configured by the above steps S1 to S5, and the gas flow rate stored in step S3 and the integrated value stored in step S5 are set as initial values.

In FIG. 3 and the above description, the integrated values of the gas flow rate and the pressure set as the initial values are described as using the values obtained by one measurement or integration operation. Can be a statistical value obtained by performing a statistical process such as an averaging process on a value obtained by a plurality of measurements or integration operations, as described later. The set of the flow rate and the integral value set as the initial value is basically one set, but may be a plurality of sets. Although not shown in FIG. 3, step S
When the use of gas is stopped or reduced during the execution of step 4, the output of the flow rate is greatly reduced, or when the output of the flow rate is greatly increased due to the use of other gas appliances, etc. Is to stop the integration operation and to execute step S3
Is cleared and the process returns to step S1. However, this initial value setting process A may occur most frequently in the actual use of gas thereafter, at a time when there is no leakage from the service pipe 2 such as immediately after the new installation of the conduit system. Reliable execution is possible by controlling the flow rate of the gas and reducing the time for integration.

As described above, in the initial value setting process A,
After setting the initial values of the integrated values of the flow rate and the pressure of the gas, the leak is monitored in the leak monitoring process B constituted by the following steps S6 to S10. That is, the leak monitoring process B
In step S6, the monitoring device 7 monitors the use of gas in the same manner as in step S1 of the initial value setting process A. The process moves to step S7. In the next step S7, it is determined whether or not the flow rate is equal to the initial value set in the initial value setting process A. If it is the same as the initial value, the process proceeds to the next step S8. If it is different from the initial value, the process returns to step S6 to continue monitoring the use of gas. In step S8, the measured value of the pressure sensor 5 of the gas meter 3 is integrated for a set time. This setting time is
It is equal to the set time of the integration in step S4 of the initial value setting process A. As described above, during the execution of step S8, the use of the gas is stopped or reduced, and the output of the flow rate is greatly reduced. When the output has increased significantly, the integration can be stopped and the process can return to step S6 to continue monitoring. Next, the monitoring device 7 compares the integrated value of the pressure obtained in step S8 with the initial value in step S9. As a result of the comparison, if it is smaller than the initial value, it is determined that the pressure of the gas at the pressure sensor 5 of the gas meter 3 is decreasing instead of fluctuating, and that the service pipe 2 is leaked. Emits output. Based on this output, corresponding processing such as generation of an alarm and shutting off of gas is performed. On the other hand, if it is not smaller than the initial value, the process returns to step S6 to continue the above monitoring. As described above, the detection of the decrease in the pressure of the gas at the location of the pressure sensor 5 is performed by comparing the integrated value obtained by integrating the pressure for the set time, and thus the decrease in the pressure due to the pressure fluctuation in a relatively short cycle within the set time. Is buried in the integral value, and it is possible to prevent such a decrease in pressure from being erroneously detected as being caused by leakage.

In the above operation, the same range is set in the magnitude judgment by comparing the integral value with its initial value in step S9, and the difference in the value within this range is ignored, and the same value is set. Can be considered. By doing so, it is possible to prevent the occurrence of a leak output when the integral value slightly decreases due to a measurement error, a long-term pressure fluctuation exceeding the integration set time, or the like. If this range is too wide, it becomes impossible to detect minute leakage of the internal pipe 2, and thus it may be set in consideration of these conditions. Further, in FIG. 3 and the above description, the integral value to be compared with the initial value is described as using the value obtained by one measurement and integral operation. As shown in (1), it is possible to compare the magnitudes by using a plurality of integrated values obtained by measuring the gas at the same flow rate as the initial value and using a plurality of integrated values and statistically using the integrated values.

Next, another example of the operation of the monitoring system to which the present invention is applied will be described. FIG. 4 is a flowchart showing an example of the flow of the operation in the initial value setting process A, and is shown in step S10.
Steps 1 to S105 change in the same manner as S1 to S5 in FIG.
Next, in this initial value setting process A, the measurement value of the flow rate measuring unit 6 of the gas meter 3 is monitored in step S106,
If there is a flow rate, it is determined whether or not the flow rate is equal to the initial value set in the initial value setting process A. If it is the same as the initial value, the process proceeds to the next step S107, and if it is different from the initial value, the process returns to step S106 to continue monitoring the use of gas. This step S10
Step 7 is performed every time the gas is used after the use of the gas corresponding to steps S101 to S105, for example, once a day. In step S107, the measured value of the pressure sensor 5 of the gas meter 3 is integrated for the same set time as in step S104, and this integrated value is stored in step S108. Next, in step S109, the number of integrated values stored so far is compared with the set value n, and it is determined whether n integrated values have been stored. As a result, if n integrated values have not been stored, the process returns to step S106 and the above operation is repeated. If n times have been stored, the process proceeds to the next step S110. In step S110, the average of the integrated values for n times is calculated, and then in step S111, the average value is stored as an initial value together with the flow rate stored in step S103. The above steps S101 to S111 constitute the initial value setting process A, and thereafter, the process proceeds to the leak monitoring process B as indicated by the connector 1. In the initial value setting process A described here, the integral value to be set as the initial value is not statistically determined by only one integration, but is statistically determined as an average value of a plurality of integral values. The effect of pressure fluctuations with a cycle longer than a day can be reduced by averaging.

FIG. 5 is a flow chart showing an example of the operation flow in the leak monitoring process B. The connector 1 is connected to the initial value setting process A. First, steps S201 to S20
3 changes in the same manner as S6 to S8 in FIG.
03 is, for example, 1 every day as in step S107.
It is performed at a frequency such as times. In this leak monitoring process B, after calculating the integral value in step S203, it is determined whether or not the history is stored by then. If no history is stored, the next step is directly performed from step S204. The process moves to S205. In step S205, the integration value obtained this time is compared with the initial value, and as a result of the comparison,
If it is smaller than the initial value, the process proceeds to step S206, and is stored as a history in the storage unit. As described below,
The contents to be stored as the history include, for example, a. The integral itself,
b. Information on the number of times of addition or subtraction, c. It can be both a and b. After the history is stored in step S206, the process returns to step S201 to perform the subsequent operations. On the other hand, if the result of comparison in step S205 is not smaller than the initial value, the process returns to step S201 via step S207 for clearing the history. If it is determined in step S204 that the history is stored, the process proceeds to step S208, and in this step S208, it is determined whether or not the set number of times, in this case, X times or more history is stored. If it is determined that X or more histories have not been stored, the process proceeds to step S2.
The process proceeds to step S05, where comparison with the initial value is performed. If the initial value is smaller than the initial value, the history is stored in step S206. When the state in which the integrated value is smaller than the initial value continues in this manner, the history increases each time. On the other hand, when the process proceeds from step S208 to step S205, if it is determined in step S205 that the value is not smaller than the initial value, the process proceeds to step S207 to clear all the history up to that point, and then proceeds to step S201. Return. As described above, the history does not increase unless the state where the integral value is smaller than the initial value continues.
Monitoring is performed by repeating the above operation. When the process proceeds from step S204 to step S208 as described above, if it is determined that X or more histories are stored, it is determined that there is leakage, and step S209 is performed. In step (1), the output is issued, and corresponding processing such as generation of an alarm and shutoff of gas is performed.

In the leak monitoring process B described here, the integral value to be compared with the initial value is not determined only by the integral of the pressure during the single use of the same amount of gas as the initial value. Since the average value of the integrated value at the time of use of gas is statistically obtained, the influence of pressure fluctuation in a cycle longer than one day can be reduced by averaging, for example, and the accuracy of leak detection can be improved. Can be measured.

FIG. 6 is a flowchart showing another example of the operation flow in the leakage monitoring process B. The connector 1 is connected to the initial value setting process A as in FIG. First, steps S301 to S303 correspond to steps S201 to S20 in FIG.
Transition is similar to 3. The leakage monitoring process B is a modification of the leakage monitoring process B shown in FIG. 5 in which the order of the steps and the like are changed, and the general operation is the same. That is, in the leak monitoring process B of FIG. 6, after the integral value is obtained in step S303, this integral value is first compared with the initial value in the next step S304. Then, as a result of the comparison, if it is smaller than the initial value, the process proceeds to step S305, and the history is stored in the storage unit. The contents of the history to be stored are determined in step S206.
Is the same as On the other hand, if the result of comparison in step S304 is not smaller than the initial value, step S30
Then, the process proceeds to step S6, and after all the histories stored so far are cleared, the process returns to step S301 to continue monitoring. As described above, the history is increased each time when the state where the integrated value is smaller than the initial value continues, but is cleared at that time when there is a state where the integrated value is not smaller than the initial value even once. It does not increase. After saving the history in step S305 as described above,
The flow shifts to 307, where the number of times stored as a history so far is determined. If the number does not exceed the preset number X, the process returns to step S301 to continue monitoring. If the number exceeds the number X, it is determined that there is leakage, and the output is issued in step S308. , And perform corresponding processing such as generation of an alarm and shutting off of gas.

Also in the leak monitoring process B described here, the integral value to be compared with the initial value is not determined only by the integral of the pressure during the single use of the same amount of gas as the initial value, but is determined by the same amount. Since it is statistically obtained as the average value of the integrated value when the gas is used a plurality of times, for example, the influence of the pressure fluctuation in a cycle longer than one day can be reduced by averaging, and the accuracy of leak detection can be improved. Can be measured.

Next, FIG. 7 is a flow chart showing still another example of the operation flow in the leak monitoring process B. As in FIGS. 5 and 6, the connector 1 is connected to the initial value setting process A. . First, steps S401 to S403 correspond to step S20 in FIG.
Transitions are made in the same manner as 1 to S203. In the leak monitoring process B, after the integral value is obtained in step S403, it is determined in the next step S404 whether the integral value indicates an abnormal value. That is, in step S404,
Judge whether the difference between the integral value and the initial value is within a preset range, and if it is not within the range, that is, if the integral value is extremely small or large compared to the initial value, Determines that the data of the integral value is invalid due to the abnormality, discards it in step S405, returns to step S401, and continues monitoring. In this way, the above range for determining the presence or absence of an abnormality in the integral value can be different or the same for the side larger than the initial value and the side smaller than the initial value. In the latter case, the integral value and the initial value By comparing the absolute value of the difference with the set value, it is possible to determine whether the integrated value is inside or outside a predetermined range based on the magnitude relationship. Next, when it is determined in step S404 that the integrated value is within the predetermined range, the process proceeds to step S406, and the integrated value is stored as a history. Then, the process proceeds to step S407 to check the number of stored histories.
It is determined whether or not N histories set in advance are stored. That is, if N histories are not stored, the process returns to step S401 to continue monitoring, and if N histories are stored, the process proceeds to the next step S408. In step S408, it is determined whether each of the stored integrated values for N times is smaller than the initial value, and the number of integrated values smaller than the initial value is determined. Then, when the number is a predetermined number, in this case, N / 2 or more, that is,
If the majority of the stored integral value is smaller than the initial value, it is determined that there is a leak, and the output is issued in step S409 to perform a corresponding process such as generation of an alarm or shutoff of gas. On the other hand, if the majority of the stored integrated values is not smaller than the initial value, it is determined that there is no leakage and step S41 is performed.
0, and after clearing all the histories, step S40
It returns to 1 and continues monitoring.

In the leak monitoring process B described here, if a set ratio or more of a plurality of integrated values within a normal range is smaller than an initial value, it is determined that there is a leak.
As in the case of the leak monitoring process B shown in FIG. 5, the integral value to be compared with the initial value is not determined only by the integral of the pressure during the single use of the same amount of gas as the initial value. Since the average value of the integrated value at the time of use of gas is statistically obtained, the influence of pressure fluctuation in a cycle longer than one day can be reduced by averaging, for example, and the accuracy of leak detection can be improved. Can be measured. The setting ratio can be set appropriately, such as 2/3 or more, in addition to the majority described above. In the history clearing operation in step S410, in addition to clearing all histories as described above, one or more histories are cleared from the oldest one, but histories newer than them are left. You can also. In this case, since the above-described leak determination can be sequentially performed using a plurality of new histories, the leak can be detected at an earlier stage than when all the histories are cleared. In this leak monitoring process B, it is determined whether the integral value is smaller than the initial value in step S4.
04, and only the determination result may be stored as a history, so that the determination in step S408 may be performed.

[0026]

As described above, the present invention has the following effects. 1. Without excavating the ground, gas leakage from a gas meter to a main pipe such as a main pipe can be detected, and drilling work such as boring is unnecessary, so that labor can be reduced. 2. Since leakage can be monitored each time gas is used, safety is improved. 3. Since the pressure drop of the conduit caused by the leak is detected by comparing with the initial value in the integrated value of the predetermined time, it is possible to average a small fluctuation of the gas supply pressure from the main pipe or the like in a relatively short period. In addition, leakage and erroneous detection can be prevented. 4. Since the integrated value is statistically processed, such as averaging, the value integrated for each use of the gas a plurality of times, it is possible to average relatively small fluctuations in the gas supply pressure from the main pipe etc. over a relatively long period. Also in this regard, it is possible to prevent the leakage detection and the erroneous detection.

[Brief description of the drawings]

FIG. 1 is a system diagram conceptually showing an example of a gas conduit system to which the present invention is applied.

FIG. 2 is an explanatory diagram showing the principle of the present invention in the system shown in FIG.

FIG. 3 is a flowchart conceptually showing an operation example of the leak monitoring system to which the present invention is applied.

FIG. 4 is a flowchart showing an example of an operation of a leak monitoring system to which the present invention is applied in an initial value setting process.

FIG. 5 is a flowchart showing an example of an operation of a leak monitoring process of the leak monitoring system to which the present invention is applied.

FIG. 6 is a flowchart showing another example of the operation of the leak monitoring process of the leak monitoring system to which the present invention is applied.

FIG. 7 is a flowchart showing still another example of the operation of the leak monitoring process of the leak monitoring system to which the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main pipe 2 Service pipe 3 Gas meter 4 Gas appliance 5 Pressure sensor 6 Flow rate measuring unit 7 Monitoring device A Initial value setting process B Leakage monitoring process

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shinichi Sato 543-15 Kitanocho, Hachioji-shi, Tokyo

Claims (10)

[Claims] 1. A gas meter is provided with a pressure sensor so that the pressure can be measured together with the flow rate of a gas flowing through a gas conduit, and when a gas flows beyond a set flow rate by using gas at a time when there is no leakage in the gas conduit. The initial value setting process in which the pressure is integrated for a set time and the integrated value and the flow rate are stored as initial values, and when the same amount of gas flows as the initial value in the subsequent gas use, the pressure is integrated for the set time. A leak monitoring process for comparing the integrated value with the initial value and determining that the gas leaks when the integrated value is smaller than the initial value. 2. In the initial value setting step, a flow rate equal to or higher than the set flow rate is stored as an initial value, and at that time and thereafter, the pressure at which the gas having the flow rate flows is integrated for a set time. 2. The system according to claim 1, wherein a plurality of pressure integrated values for the same flow rate are obtained, and an average value thereof is used as an initial value of the pressure integrated value. 3. In the leak monitoring process, each time the same amount of gas flows as the initial value, the pressure is integrated for a set time and the integrated value is compared with the initial value. 3. A system for monitoring gas leakage from a gas conduit according to claim 1 or 2, wherein the system is determined to be a gas leak when the gas leakage occurs. 4. In the leak monitoring process, the pressure is integrated for a set time at each time when the same amount of gas flows as the initial value, the integrated value is compared with the initial value, and the state where the initial value is not reached is stored in the storage means. In the case where the history is stored as a history, the history of the storage means is otherwise cleared and the monitoring is continued, and the number of times that the integral value does not reach the initial value is obtained from the history of the storage means, and the number of times reaches the set number of times. 4. The system for monitoring gas leakage from a gas conduit according to claim 3, wherein the system is determined to be a gas leakage. 5. The storage device according to claim 4, wherein the storage means stores only the number of times when the initial value is not reached.
System for monitoring leakage of gas from gas conduit as described 6. The storage means is configured to store data of an integral value of the pressure when the integral value of the pressure does not reach an initial value, and obtains the number of times of not reaching the initial value from the number of stored data. 5. A system for monitoring gas leakage from a gas conduit according to claim 4. 7. In the leak monitoring process, the pressure is integrated for a set time every time when the same amount of gas flows as the initial value, the integrated value is compared with the initial value, and the absolute value of the difference between the integrated value and the initial value is calculated. In addition to extracting data whose value is smaller than the set value, extracting data whose integral value is smaller than the initial value from the extracted set number of data, and determining that the gas leaks when the number has reached the set number. A system for monitoring gas leakage from a gas conduit according to claim 1 or 2, 8. In the leak monitoring process, each time the same amount of gas flows as the initial value, the pressure is integrated for a set time, the integrated value is compared with the initial value, and the absolute value of the difference is set to the set value. Any data larger than this is discarded, the other data is stored in the storage means, and when the number of stored integrated values reaches the set number, each stored data is compared with the initial value. 8. The system according to claim 7, wherein the number of data that does not reach the initial value is obtained, and when the number of data is larger than the set number, it is determined that the gas is leaking. 9. The gas leakage detection device according to claim 1, wherein a set of a gas flow rate and an integral value set as an initial value is one set. Method 10. The method according to claim 1, wherein a set of a gas flow rate and an integral value set as an initial value is a plurality of sets.
The method for detecting gas leakage from a gas conduit according to any one of the above items