JP3622886B2 - Gas shut-off device and gas shut-off method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas shut-off device and a gas shut-off method for shutting off a gas in a gas supply path during a fire or the like.
[0002]
[Prior art]
Conventionally, in the gas supply route, when the gas flow becomes an excessive flow rate due to gas leakage, etc., the means for shutting off the gas supply when the total flow rate within a certain time exceeds a predetermined value, or when there is an earthquake, etc. For example, a gas meter that measures a gas flow rate and that incorporates a shut-off valve is generally used. In a conventional aluminum die-cast gas meter, the casing does not melt even in the event of a fire or the like, so there is almost no risk of gas leaking outside the meter. For this reason, there was no means for shutting off the gas in the event of a fire.
[0003]
In recent years, there has been a tendency to use synthetic resin instead of metal as a material for gas piping in order to shorten construction time and reduce piping costs. Gas meters are also equipped with a housing for weight reduction and cost reduction. It has been proposed to make the body resin. Japanese Utility Model Laid-Open No. 2-119600 discloses an automatic gas shut-off device provided with means for shutting off a gas at a high temperature such as a fire when a gas pipe formed of a synthetic resin is used.
[0004]
[Problems to be solved by the invention]
In adopting a gas meter formed of a synthetic resin in the casing as described above, it is necessary to block gas at a high temperature such as a fire to prevent gas outflow. In the conventional configuration, gas shutoff at a high temperature is not particularly taken into consideration, so that in the event of a fire or the like, the gas may flow out due to melting of the gas meter casing.
[0005]
The present invention has been made in view of the above-described problems, and its purpose is to enable gas to be shut off at a high temperature such as a fire with a simple configuration and a simple configuration, and to prevent gas outflow. An object of the present invention is to provide a gas cutoff device and a gas cutoff method.
[0006]
[Means for Solving the Problems]
The gas shut-off device according to the present invention, as described in claim 1, is a pressure detection means for detecting the pressure in the gas supply path, a time measurement means for measuring a predetermined time, and a predetermined time measured by the time measurement means. At each sampling time, the pressure change rate in the gas supply path is calculated based on the output of the pressure detection means, and the gas flow path is shut off when the pressure change rate is greater than a reference value that can determine the occurrence of a fire. And a gas shut-off control means.
[0009]
According to the gas shutoff method of the present invention, as described in claim 2, the pressure detection step for detecting the pressure in the gas supply path, the time measurement step for measuring a predetermined time, and the predetermined time measured in the time measurement step A pressure change rate calculating step for calculating a pressure change rate in the gas supply path based on the pressure value obtained in the pressure detecting step, and a reference value for determining the pressure change rate and the occurrence of fire And a gas cutoff control step of shutting off the gas flow path when the rate of change in pressure is greater than a reference value with which the occurrence of fire can be determined .
[0012]
In the gas shut-off device and the gas shut-off method according to the present invention, the gas shut-off control means is configured to provide the gas shut-off control means within the gas supply path based on the pressure value detected by the pressure detecting means at every predetermined sampling time measured by the time measuring means. By calculating the rate of change in pressure and shutting off the gas flow path when the rate of change in pressure is greater than the reference value at which it is possible to determine the occurrence of a fire, a pressure increase due to a rapid temperature increase at a high temperature such as a fire is detected. Gas can be shut off.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram showing a configuration of a gas cutoff device according to an embodiment of the present invention.
The gas shut-off device of the present embodiment is a pressure sensor 13 as a pressure detecting means for detecting the pressure in the gas meter 11 or the gas pipe 12 and a gas shut-off control means for performing shut-off control based on the output of the pressure sensor 13. A microcomputer 14 and a time counter 15 connected to the microcomputer 14 as time measuring means for counting a predetermined time are configured.
[0014]
The gas meter 11 includes substantially the same components as a general gas meter, that is, a flow rate detection unit, a pressure sensor, a shutoff valve, a control unit including a microcomputer, and a display unit, and flows through the gas pipe 12. The gas flow rate is measured. Note that the gas meter 11 uses metal members at least around the gas inlet and the shutoff valve even when the casing is formed of a resin member.
[0015]
The pressure sensor 13 detects the internal pressure in the gas meter 11 or in the gas pipe 12, that is, in the gas supply path. For example, a pressure sensor provided in the gas meter 11 can be used. When a pressure sensor is provided in the gas meter 11, it is desirable to arrange it near the meter inlet.
[0016]
For example, the microcomputer 14 is configured by using a processor having a capability equal to or higher than that of a processor provided in a general gas meter, and operating by a software program having a pressure rise cutoff function. The microcomputer 14 is built in the gas meter 11 or provided outside. The time counter 15 measures time using a built-in microcomputer 14 or an external counter.
[0017]
Next, the operation of the gas cutoff device will be described with reference to FIGS. FIG. 2 is an explanatory diagram showing an example of a pressure change in the gas supply path over time, and FIG. 3 is a flowchart showing the operation of the microcomputer related to the pressure rise blocking function.
[0018]
The microcomputer 14 detects the pressure in the gas supply path (in the gas meter 11) by the pressure sensor 13 every predetermined sampling time T based on the time (time measurement step) measured by the time counter 15 (pressure detection step). ). Then, the pressure change rate a during this period is calculated (step S1, pressure change rate calculating step).
[0019]
When the gas is not used, the pressure sensor 13 detects the pressure in the gas meter 11 approximately every 10 minutes. That is, the sampling time T in the initial state is set to T = T1 = 10 [min (min)]. Thereafter, the pressure change rate a is compared with a predetermined reference value (pressure determination step).
[0020]
In the present embodiment, first, it is determined whether or not the pressure change rate a exceeds a predetermined determination reference value α (α1 when gas is not used) (a> α) (step S2). In the example of FIG. 2, since the pressure change rate a1 from time 0 to time t1 is a1 = 0, the process returns from step S2 to step S1, and the operation mode according to the sampling time T1 in this initial state until a> α is satisfied. The pressure change rate a is continuously detected (hereinafter referred to as a normal mode).
[0021]
Further, when the gas is used, the pressure change rate is calculated and compared with the reference value in the initial state in the initial state, with the sampling time T set to 10 minutes, as in the case of no gas. However, since gas flows through the gas meter 11 and the gas pipe 12, the determination reference value α is set to α2 in consideration of the pressure change due to the gas flow rate.
[0022]
When the pressure change rate a2 becomes a2> 0 and further a2> α1 from time t1 to time t2, the sampling time T is changed short (step S3). That is, the changed sampling time T is set to T = T2 <T1, for example, T2 = 5 [minutes], and the pressure change rate a is calculated by shortening the detection period. Thereafter, similarly to step S2, it is determined whether or not the short-time pressure change rate a in the sampling time T2 exceeds the determination reference value α (a> α) (step S4). The operation mode with the shortened sampling time T2 is hereinafter referred to as a detailed mode.
[0023]
As shown by the alternate long and short dash line in FIG. 2, when the pressure in the gas supply path rises due to the weather or the like, such as a pressure rise caused by a temperature rise due to sunlight, the degree of the pressure rise is small, and the pressure changes over time. The rate a converges to almost zero. Accordingly, when the pressure change rate a is equal to or less than the determination reference value α in the detailed mode of step S4, it is regarded as a pressure increase accompanying a temperature increase due to weather or the like, and the process returns to step S1 to shift to the normal mode, and the sampling time The pressure change rate a due to T1 is detected.
[0024]
In step S4, if the pressure change rate a for a short time is a> α, whether or not the second determination reference value εα multiplied by a predetermined coefficient ε is exceeded (a> εα), and a comparative determination is performed again (step S5). . Here, as shown by the solid line in FIG. 2, when the pressure rapidly increases and the pressure change rate a3 is sufficiently large, the second determination reference value εα is exceeded, which is accompanied by an abnormal increase in ambient temperature due to the occurrence of a fire. Judged as a pressure increase. In this case, the microcomputer 14 outputs a shut-off signal, closes a shut-off valve (not shown), and shuts off the gas supply path (gas shut-off control step). As the shut-off valve, a solenoid valve or the like using a solenoid may be used. The shut-off valve provided in the gas meter 11 is used, or the shut-off valve is provided separately in the middle of the gas pipe 12.
[0025]
If the pressure change rate a is equal to or smaller than the second determination reference value εα in step S5, the process returns to step S4 and the next period is compared again with the pressure change rate a based on the sampling time T2 and the determination reference value α. If it is equal to or less than the determination reference value α, it is considered that the pressure is increased due to a temperature increase due to weather or the like, and the process returns to step S1 to shift to the normal mode.
[0026]
Note that the microcomputer 14 has an overflow cutoff function that detects the gas flow rate in the gas meter 11 and the gas pipe 12 and shuts off the gas supply in the case of an overflow rate, in the same manner as a conventionally used gas meter. I have to. When the gas flows out due to damage or flame on the downstream side of the gas pipe 12 from the gas meter 11, the flow rate becomes excessive, and the gas supply path is blocked by this overflow blocking function.
[0027]
As described above, according to the present embodiment, when the rate of change in pressure in the gas supply path for a predetermined time exceeds a predetermined reference value, the gas flow path is cut off, so that it can be used at a high temperature such as a fire. It is possible to shut off the gas by detecting a pressure rise accompanying a rapid temperature rise. In this case, the above-described pressure rise shut-off function can be realized with a simple configuration without making a major change to the configuration of the gas supply path including the conventional gas meter and with a simple configuration.
[0028]
If a gas shut-off device having this pressure rise shut-off function is employed, it becomes possible to ensure safety when a resin member is used for the gas meter casing, gas piping, or the like. For this reason, no matter what material is used for the gas meter or the like, the gas can be shut off at a high temperature such as a fire, and the outflow of the gas can be prevented. Therefore, it is possible to reduce the weight and cost of the components of the gas supply path.
[0029]
【The invention's effect】
As described above, according to the gas shut- off device and the gas shut-off method of the present invention, the gas shut- off control means sets the pressure value detected by the pressure detecting means at every predetermined sampling time measured by the time measuring means. Based on this, the rate of change in pressure in the gas supply path is calculated, and when the rate of change in pressure is greater than the reference value that can determine the occurrence of a fire , the gas flow path is shut off. It is possible to shut off the gas by detecting the pressure rise accompanying the rise, and it is possible to shut off the gas at a high temperature such as a fire with a simple configuration and with a simple configuration, and it is possible to prevent gas outflow An effect is obtained.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a configuration of a gas cutoff device according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing an example of a pressure change in a gas supply path with time.
FIG. 3 is a flowchart showing the operation of the microcomputer related to a pressure rise shut-off function.
[Explanation of symbols]
11 Gas meter 12 Gas piping 13 Pressure sensor 14 Microcomputer 15 Time counter

Claims (2)

Pressure detecting means for detecting the pressure in the gas supply path;
A time measuring means for measuring a predetermined time;
At each predetermined sampling time measured by the time measuring means, the pressure change rate in the gas supply path is calculated based on the output of the pressure detecting means, and this pressure change rate is based on a reference value that can determine the occurrence of a fire. And a gas shut-off control means for shutting off a gas flow path when it is large. A pressure detection step for detecting the pressure in the gas supply path;
A time measurement step for measuring a predetermined time;
A pressure change rate calculating step for calculating a pressure change rate in the gas supply path based on the pressure value obtained in the pressure detecting step at every predetermined sampling time measured in the time measuring step;
A pressure determination step of comparing the pressure change rate with a reference value capable of determining the occurrence of a fire ;
A gas shutoff control step of shutting off a gas flow path when the pressure change rate is larger than a reference value by which the occurrence of the fire can be determined .

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