JPH09273970A - Electro-static pressure sensor and gas abnormality monitor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure long-period stability of a pressure sensor by oppositely disposing a fixed board for forming a first electrode and a diaphragm for forming a second electrode, and providing a liquid part therebetween. SOLUTION: A fixed board 31 forms a first electrode (sensitive electrode) 33A and a first electrode (reference electrode) on its surface, and a diaphragm 32 shapes a second electrode 34 on its surface. The first electrodes 33A, 33B are oppositely disposed to the second electrode 34, and the fixed board 31 is bonded to the diaphragm 32 through a bonding layer 37. After liquid which has small water absorbance, evaporation and viscosity is dropped in a vent 35, they are set in a pressure-reduced vessel, a clearance between the fixed board 31 and the diaphragm 32 is filled with liquid (perfluoropolyether) to provide a liquid part 36 and a sensor element is manufactured. Thereby temperature correction of filling liquid is facilitated, liquid is not absorbed, not evaporated to be reduced, and temperature can be quickly followed up to pressure fluctuation. Thus, long-period stability of a pressure sensor can be secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitance type pressure sensor for detecting a pressure change of a fluid such as gas pressure and a gas abnormality monitoring device using this sensor.

[0002]

2. Description of the Related Art In recent years, in order to improve the safety of city gas or LP gas equipment, for example, in the case of a gas meter, if an abnormal situation occurs downstream from the gas meter,
It has been considered to incorporate a gas abnormality monitoring device that automatically shuts off gas supply into a gas meter. As for the pressure regulator, the incorporation of a gas abnormality monitoring device capable of automatically performing a safety management check, such as an abnormal adjustment pressure of the pressure adjusting means or a gas leak detection from the LP gas cylinder to the gas meter, is being studied. When the pressure regulating function of the pressure regulator of the LP gas is operating normally, the gas appliance use state supply pressure of the gas is kept between 230~330mmH ₂ O, or the gas supply pressure is normal Is monitored by a pressure sensor. Also, if there is an abnormality such as a gas leak in the gas facility, for example, if the shutoff valve is operated and the gas pipe is closed, the gas pressure will gradually decrease due to the gas leak (several mmH ₂
Since the pressure is 0 to several tens of mmH ₂ O), it is possible to detect whether or not there is an abnormality such as a gas leak in the gas equipment by monitoring this decrease in gas pressure.

Since these devices in which the pressure sensor is incorporated are exposed to an atmosphere containing foreign matter such as fine dust, mist, oil contained in the gas pipe or the gas itself, the sensor causes abnormal operation due to these foreign matter. Used in an easy environment. On the other hand, these devices are required to have high reliability that their characteristics must not change over a long period (about 10 years). Capacitive pressure sensors are considered promising as pressure sensors that can satisfy such characteristics. The electrostatic capacitance type pressure sensor utilizes the fact that the diaphragm is deformed by pressure and the distance between the electrodes is changed, so that the electrostatic capacitance generated between the electrodes is changed. The conventional capacitance type pressure sensor element described in Japanese Patent Application Laid-Open No. 7-49244 shown in FIG. 7 has a movable electrode 4 and a fixed electrode 3 formed on a frame 1 and a cover 2.
The space 6 surrounded by the space is filled with a high dielectric constant liquid such as silicon oil. The cover 2 is provided with a mesa portion 7 and a plurality of differential pressure holes 5, and when the pressure fluctuates, the liquid having a high dielectric constant moves back and forth between the space 6 and the differential pressure holes 5.

[0004]

However, in the pressure sensor used in the conventional gas abnormality monitoring device such as the gas meter and the pressure regulator, it is not possible to maintain the highly accurate performance for a long period of time. When detecting the differential pressure (gauge pressure) between the gas to be measured and atmospheric pressure with a capacitance type pressure sensor, moisture and foreign matter enter the capacitance detection section between the substrate and diaphragm through the fine holes for introducing the atmosphere. Then, since there is a phenomenon that the capacitance between the electrodes changes or an abnormal characteristic is exhibited, there is a problem that it is difficult to maintain the function of the pressure sensor for a long period of time. That is, in the capacitance type pressure sensor described in the prior art, when detecting the differential pressure (gauge pressure) between the measured gas and atmospheric pressure,
It is difficult to correct the temperature because the temperature change of the capacitance formed by the liquid of high dielectric constant such as silicon filled between the movable electrode and the fixed electrode is larger than that of air, and it is difficult to correct the temperature difference. Since it is open, water may dissolve into the high dielectric constant liquid from the differential pressure hole and the high dielectric constant liquid may be altered, or the high dielectric constant liquid may easily evaporate and an air layer may be generated between the gaps. However, there is a problem that the pressure response is poor due to the viscosity of the liquid having a high dielectric constant, or the liquid having a high dielectric constant is washed away from the differential pressure hole depending on the mounting posture of the sensor.

If the pressure sensor deteriorates over time while the gas abnormality monitoring device is operating for a long period of time, the gas abnormality monitoring device is likely to make an erroneous determination that there is an abnormality in the gas facility. Therefore, since it is necessary for an operator to regularly inspect and calibrate the characteristics of the pressure sensor, it takes a lot of labor and cost to inspect and calibrate the pressure sensor, and the gas abnormality monitoring device becomes very expensive. there were.

The present invention is intended to solve such conventional problems, and its main purpose is to prevent the characteristics of the pressure sensor from changing over a long period of time.

[0007]

In the present invention, a fixed substrate having a first electrode formed thereon and a diaphragm having a second electrode formed thereon are opposed to each other, and a liquid is provided between the diaphragm and the fixed substrate. Parts are provided.

According to this invention, the characteristics of the pressure sensor do not change over a long period of time.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In order to achieve the above object, the present invention provides a fixed substrate made of an electrically insulating material having a first electrode formed on one surface, and an electrically insulating substrate having a second electrode formed on one surface. A diaphragm made of a flexible elastic material, the first electrode and the second electrode are arranged to face each other, and the diaphragm is formed on the peripheral portion of at least one of the first electrode and the second electrode, and the fixed substrate. A capacitance type pressure sensor comprising an adhesive layer in which the diaphragm is joined with a minute gap, one atmospheric hole provided in the fixed substrate, and a liquid portion filled between the diaphragm and the fixed substrate. is there.

Further, in order to achieve the above object, the present invention provides
A gas pressure is detected by the capacitance type pressure sensor, a determination unit that determines an abnormality of the capacitance type pressure sensor based on an electric signal from the capacitance type pressure sensor, and the capacitance type pressure sensor. Gas equipment, a flow rate detection means for detecting a gas flow rate of the gas equipment, a determination means for determining an abnormality of the gas equipment by an electric signal from the capacitance type pressure sensor and the flow rate detection means, and the determination And a gas abnormality monitoring device including an operating unit that operates according to a signal from the unit.

The present invention has the following effects due to the above configuration. That is, in the capacitance type pressure sensor of the present invention, the first electrode or the second electrode is composed of the pressure sensitive electrode and the reference electrode, and the fixed substrate has only one atmospheric hole. By filling the minute space between the diaphragm and the fixed substrate with a liquid with low water absorption, evaporation and viscosity, it is easy to correct the temperature of the filled liquid, there is no leakage of the filled liquid, and there is no water absorption. That is, the liquid does not evaporate and decreases, and it is possible to quickly follow the pressure fluctuation. Therefore, the characteristics of the pressure sensor do not change over a long period of time, and temperature compensation of the pressure sensor is easily performed, so that a small and low-cost pressure sensor can be obtained.

Further, since the pressure sensor itself has the above-mentioned function, it is not necessary to regularly inspect the pressure sensor, and in the gas abnormality monitoring device, the inspection work of the gas abnormality monitoring device can be saved. Further, since the self-diagnosis function of the pressure sensor is performed with low power, the pressure sensor can be operated with a small number of batteries, and the gas abnormality monitoring device can be downsized and reduced in cost.

(Embodiment 1) Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. 1, 2, 3 and 4.

In FIG. 1, a fixed substrate 31 of an electrically insulating material having a first electrode (pressure sensitive electrode) 33A and a first electrode (reference electrode) 33B formed on the surface thereof, and a second electrode 34 on the surface thereof. A diaphragm 32 made of an electrically insulating elastic material and an adhesive layer 37 formed on the peripheral portion of at least one of the first electrode 23 and the second electrode 34. ) 33A and first electrode (reference electrode) 33B
Are arranged to face the second electrode 24, and the fixed substrate 31 and the diaphragm 32 are bonded to each other via the adhesive layer 37. A liquid having low water absorption, evaporation and viscosity is dropped into the vent hole 35 of the sensor element and then set in a depressurized container to fill the liquid (perfluoropolyether) into the gap formed by the fixed substrate 31 and the diaphragm 32. Then, the sensor element having the liquid portion 36 is manufactured. When a certain pressure is applied to the diaphragm 32, the diaphragm 32 is bent in accordance with the pressure difference between the certain pressure and the atmospheric pressure. The deflection of the diaphragm 32 is calculated by comparing the capacitance value of the first electrode (pressure sensitive electrode) 33A and the second electrode 34 with the capacitance value of the first electrode (reference electrode) 33B and the second electrode 34. A non-linearity correction and gain / offset adjustment are performed through a circuit (not shown) to output a predetermined output and the data is taken out to the outside. The dielectric constant of gas (eg air) is about 1 and its temperature coefficient is very small, whereas the dielectric constant of liquid (eg perfluoropolyether) is about 2 and its temperature coefficient is several hundred ppm / ° C. Therefore, the dielectric constant changes greatly with temperature. Therefore, the temperature correction of the dielectric constant can be performed by making the pressure sensitive electrode 33A and the reference electrode 33B coexist in the gap filled with the liquid and performing the comparison calculation.

Here, the liquid portion 36 having low water absorption, evaporation and viscosity has almost zero water absorption at low temperature (-30 ° C.) to high temperature (70 ° C.), and vapor pressure of 10-4.
It is smaller than Torr and has a viscosity smaller than 5000 cst. For example, perfluoropolyether, trimethylpentaphenyltrisiloxane, tetramethylphenyltrisiloxane, pentaphenylether, and isosealnaphthalene are preferable as materials. .

The capacitance type pressure sensor of the present invention was subjected to a high temperature and high humidity test (temperature 60 ° C., humidity 95% RH, 1000 hours) and a cycle test (temperature 70 ° C. * hold for 1 hour, temperature -30 ° C.).
* After maintaining for 1 hour as 1 cycle and total 500 cycles), the characteristics of the sensor are measured and evaluated. When the pressure is 0 to 500 mmH ₂ O, the output voltage is 0.2 to 1.2 V and the accuracy is 0.5% full scale ( 2.5 mmH ₂ O), and there was almost no change in the sensor characteristics (0.1% full scale drift).

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. 1, 2 and 3. FIG. 2 is a block diagram of an embodiment of the gas abnormality monitoring device of the present invention. In FIG. 2, 12 is a pressure regulator, 13 is a gas abnormality monitoring device, and 14 is a gas facility. Gas abnormality monitoring device 1
3 is a pressure sensor 21, a flow rate detecting means 22 (for example, a flow meter), a judging means 23 (for example, a microcomputer), and an operating means 24.
(For example, a shutoff valve).

FIG. 3 is a flow chart showing the operation of the gas abnormality monitoring device 13. For gas leak detection, the operating means 24 (for example, a shutoff valve) is operated to detect the flow rate and the presence or absence of pressure fluctuations when the gas facility 14 is not used by the flow rate detecting means 22 and the pressure sensor 21, and the determining means. This is done by judging at 23. That is, if a small amount of gas is leaking, when the gas flow rate is 0, the gas pressure in the pipe gradually decreases with time. The state of this slight change in gas pressure is monitored by the pressure sensor 21 and is judged by the judging means 23 such as a microcomputer. If the pressure drop is larger than a predetermined value, it is judged that there is gas leakage, and the operating means 24 shutoff valve ) To work. When the determination unit 23 determines that there is no gas leakage, the operation unit 24, the pressure sensor 21, and the flow rate detection unit 22 are operated again to measure the pressure and flow rate of the gas facility 14 to monitor a long-term gas leak. To do.

The capacitance type pressure sensor 21 described in the first embodiment is incorporated in the gas abnormality monitoring device 13, and a simulated gas piping system is used so that there is a slight leak from the gas piping. The relationship with gas pressure was investigated.
That is, the actual gas pressure of the gas facility 14 is 200 mmH ₂ O.
The gas abnormality monitoring device 13 and the gas facility 14 were measured (measured by a pressure sensor of another standard) while the cock of the gas facility 14 and the shutoff valve as the operating means 24 were closed to reduce the gas flow rate to zero. As a result of investigating the pressure change of the gas pipe between and, it was possible to measure that the gas pressure dropped by about 6 mmH ₂ O in 20 seconds, and it was possible to detect the presence or absence of a slight leak from the gas pipe in a short time. . Detects gas pressure fluctuations in a short time
Since it was possible to determine, it was possible to reduce the power consumption of the gas abnormality monitoring device, and it was not necessary to replace the battery for 10 years. Furthermore, as a result of conducting field tests in cold regions and hot and humid regions, it was possible to operate normally for 10 years or more, and it was possible to reduce running costs because it did not require periodic pressure sensor calibration.

(Embodiment 3) Next, Embodiment 3 of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

FIG. 6 shows another embodiment of the electrostatic capacity type pressure sensor of the present invention. Compared with the structure of the electrostatic capacity type pressure sensor of the first embodiment, the fixed substrate 31 has a first electrode 33A and a first electrode 33A. The difference is that a wiring hole 38 for wiring the wiring of the second electrode 33B on the opposite side is provided and a sealing portion 39 is provided for sealing the wiring hole 38. The wiring hole 38 is the first electrode 3
In order to reduce the stray capacitance by shortening the wiring as much as possible when connecting 3A and 33B and the second electrode 34 to the circuit provided on the opposite side, the liquid to be filled is more reliably fixed substrate 31 and diaphragm 32. This is for filling the gap formed in (4). That is, when filling the pressure sensor with liquid,
If there is only one inlet, it is possible to decompress the gap formed by the fixed substrate 31 and the diaphragm 32 with a decompressed container and then immerse it in the liquid to fill the gap by a capillary phenomenon. Difficult with large liquids. On the other hand, if there are a plurality of inlets, even if the liquid has a large surface tension, the liquid can be filled in the gap by the same method.
However, if there are a plurality of inlets, the filled liquid is likely to move, the liquid is easily evaporated, and water is easily absorbed. Therefore, the wiring hole 38 is filled with the liquid and then sealed by the sealing portion 39. Similar to the first embodiment, a liquid (perfluoropolyether) is filled in the gap formed by the fixed substrate 31 and the diaphragm 32 to manufacture a sensor element having the liquid portion 36, and the wiring hole 38 is soldered (sealed). Stop 39)
And the sensor circuit was soldered to form a capacitance type pressure sensor.

The capacitance type pressure sensor of the present invention was subjected to a high temperature and high humidity test (temperature 60 ° C., humidity 95% RH, 1000 hours) and a cycle test (temperature 70 ° C. * 1 hour hold, temperature -30 ° C.).
* After maintaining for 1 hour as 1 cycle and total 500 cycles), the characteristics of the sensor are measured and evaluated. When the pressure is 0 to 500 mmH ₂ O, the output voltage is 0.2 to 1.2 V and the accuracy is 0.5% full scale ( 2.5 mmH ₂ O), and there was no change in the sensor characteristics (0.1% full scale drift).

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIGS. 6, 4 and 5.

FIG. 4 is a block diagram of the gas abnormality monitoring apparatus of the present invention. In FIG. 4, 11 is a gas supply source, 13 is a gas abnormality monitoring device, and 14 is a gas facility. The gas abnormality monitoring device 13 includes a pressure adjusting unit 20, a capacitance type pressure sensor 21, a flow rate detecting unit 22 (for example, a flow meter), a determining unit 23 (for example, a microcomputer), and an operating unit 24 (for example, a shutoff valve). ing.

FIG. 5 is a flow chart showing the operation of the gas abnormality monitoring device 13. In the state where the present apparatus is started, the gas pressure supplied from the gas supply source 11 and adjusted by the pressure adjusting means 20 is the capacitance type pressure sensor 21.
Is measured (step 1), the flow rate detecting means 22 measures the flow rate to confirm that there is a gas flow rate (step 2), and the normal gas usage pattern is stored in the determining means 23 such as a microcomputer. The capacitance pressure sensor 21 and the flow rate detecting means 22 are constantly monitored for changes in gas pressure and flow rate, and when a gas pressure and flow rate different from the normal gas usage pattern are detected, those values are determined to be predetermined values. If it is larger than the value, the judging means 23 judges that the pressure adjusting means 20 of the gas abnormality monitoring device 13 has an abnormality (step 3). When it is determined that there is an abnormality in the gas facility, the operating means 24 (eg, shutoff valve)
To stop the gas supply (step 4).
In addition, if the gas equipment is inspected and it is confirmed that there is no abnormality or if there is no abnormality, the procedure returns to the pressure measurement operation (step 1) again, and measurement / judgment is continuously performed.
The long-term change of the pressure adjusting means 20 of the gas abnormality monitoring device 13 is monitored.

When the electrostatic capacity type pressure sensor 21 of the third embodiment shown in FIG. 6 is used in FIG. 4, the pressure adjusting means 20 is used.
The adjustment pressure by 315 mmH ₂ O (measured by another standard pressure sensor) can be measured with an accuracy of 1 mmH ₂ O or less, and it can be judged in about 30 seconds that there is no abnormality in the adjustment pressure. It was Since it was possible to detect and discriminate the gas pressure fluctuation in a short time, it was possible to reduce the power consumption as a gas abnormality monitoring device, and it was not necessary to replace the battery for 10 years. Also, as a result of conducting field tests in cold regions and hot and humid regions, it was possible to operate normally for more than 10 years, and it was possible to reduce the running cost because it did not require periodic calibration of the pressure sensor.

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. The basic structure is the same as that described in the first embodiment, but the volume of the vent holes 35 is fixed.
The volume of the portion surrounded by the diaphragm 32 and the adhesive layer 37 is set to 0.5 to 1.5 times. The liquid filled in the portion surrounded by the fixed substrate, the diaphragm, and the adhesive layer is extruded to the outside when pressure is applied to the diaphragm or the outside temperature rises and thermal expansion occurs. At this time, if the volume of the vent hole 35 is smaller than 0.5 of the volume of the filled liquid, the liquid leaks out. Further, if the volume of the vent holes 35 is larger than 1.5 of the volume of the filled liquid, the opening area of the vent holes 35 becomes large and the vaporization easily occurs, or the fixed substrate becomes thick and the plate thickness becomes thick. However, the cost becomes high and the wiring between the front surface and the back surface becomes difficult. That is, the volume of the ventilation hole 35 is equal to that of the fixed substrate 3.
A pressure sensor having 0.5 times, 0.8 times, 1.2 times, and 1.5 times the volume of the portion surrounded by 1, the diaphragm 32, and the adhesive layer 37 was manufactured. Similar to Example 1, these pressure sensors were subjected to a high temperature and high humidity test (temperature 60 ° C., humidity 95% RH, 10%).
00 hours) and cycle test (temperature 70 ℃ * 1 hour hold,
Temperature -30 ° C * Total of 5 with 1 hour holding as 1 cycle
00 cycles) after, when evaluated measuring characteristics of any of the sensors, the output voltage at a pressure 0~500mmH ₂ O 0.
2 to 1.2V, accuracy 0.4% full scale (2.5mmH
₂ O), and the sensor characteristics did not change (0.08
% Full scale drift).

Next, as a comparative example, a gas abnormality monitoring apparatus using a capacitance type pressure sensor 44 having a plurality of differential pressure holes opened to the atmosphere will be described with reference to FIGS. 7 and 2.

In the sensor element, as shown in FIG. 7, a space 6 formed between the movable electrode 4 and the fixed electrode 3 formed in the frame 1 and the cover 2 is filled with a liquid having a high dielectric constant such as silicon oil, and the cover 2 Is provided with a mesa portion 7 and a plurality of differential pressure holes 5. When the temperature changed from −30 ° C. to 60 ° C., the initial capacitance was 80.43 pF.
It was a large change of 81 pF. The initial capacity is 74.24.
When a temperature cycle test was repeated 100 times, in which the temperature of 70 ° C. was held for 1 hour and the temperature of −30 ° C. was held for 1 hour, the temperature of the sensor was 76.12 pF, which was a large change. In either case, the circuit could not correct. When the temperature sensor was tilted and installed in a temperature cycle test, the filled high-dielectric constant liquid leaked out.

When this capacitance type pressure sensor was incorporated in the same gas abnormality monitoring device as in Example 2, the same high temperature and high humidity test (temperature 60 ° C., humidity 95% RH, 1000 hours) and cycle test (temperature) were carried out. 70 ℃ * 1 hour hold, temperature-
After carrying out a total of 500 cycles with one cycle of holding at 30 ° C * 1 hour, the actual adjustment pressure of the pressure regulator was 31
Despite being 5 mmH ₂ O (measured by another standard pressure sensor), it was judged that the pressure adjusting means was abnormal. In addition, as a result of conducting field tests in cold areas and hot and humid areas, abnormal operation was observed after about 4 years had passed.

In the gas abnormality monitoring device of the present invention,
Various materials for capacitive pressure sensor (liquid, diaphragm, fixed substrate, etc.), sensor shape (diameter, electrode pattern, thickness, gap, diaphragm, etc.), installation location, circuit configuration, measured pressure, various reliability test methods The configuration of the gas abnormality monitoring device is not limited to this embodiment.

[0032]

As is apparent from the above description, according to the pressure sensor of the present invention and the gas abnormality monitoring device using this pressure sensor, the following effects can be obtained.

In the pressure sensor of the present invention, the first electrode or the second electrode is composed of the pressure sensitive electrode and the reference electrode, the fixed substrate has only one atmospheric hole, and the diaphragm. By filling a small space between the fixed substrate and the fixed substrate with a liquid with low water absorption, evaporation and viscosity, it is easy to correct the temperature of the filled liquid, there is no leakage of the filled liquid, no water absorption, and liquid Will not evaporate and decrease, and it will be possible to quickly follow pressure fluctuations. Therefore, the characteristics of the pressure sensor do not change over a long period of time, and temperature compensation of the pressure sensor is easily performed, so that a small and low-cost pressure sensor can be obtained.

Therefore, in the gas abnormality monitoring device,
By using the pressure sensor with the above configuration, it is possible to shorten the gas equipment abnormality determination time, shorten the pressure sensor operating time to suppress battery consumption, and perform periodic pressure sensor calibration and adjustment. It can be unnecessary.

[Brief description of drawings]

FIG. 1 is a sectional view of a pressure sensor showing Embodiments 1 and 2 of the present invention.

FIG. 2 is a block diagram showing a gas abnormality monitoring device using the same sensor.

FIG. 3 is a flowchart of the apparatus.

FIG. 4 is a block diagram showing a gas abnormality monitoring device according to another embodiment of the present invention.

FIG. 5 is a flowchart of the apparatus.

FIG. 6 is a sectional view of another embodiment of the pressure sensor of the present invention.

FIG. 7 is a sectional view of a conventional capacitance type pressure sensor.

[Explanation of symbols]

 31 Fixed Substrate 32 Diaphragm 33A First Electrode (Pressure Sensitive Electrode) 33B First Electrode (Reference Electrode) 34 Second Electrode 35, 37 Adhesive Layer 36 Liquid Part

Claims (16)

[Claims] 1. A fixed substrate made of an electrically insulating material having a first electrode formed on one surface, a diaphragm made of an electrically insulating elastic material having a second electrode formed on one surface, and the first electrode. And an adhesive layer in which the second electrode is disposed so as to face each other and is formed on at least one peripheral portion of the first electrode and the second electrode, and the fixed substrate and the diaphragm are joined with a minute gap therebetween. , A hole provided in the fixed substrate,
A capacitance type pressure sensor comprising a liquid part filled between the diaphragm and the fixed substrate. 2. The capacitance type pressure sensor according to claim 1, wherein the first electrode or the second electrode comprises a pressure sensitive electrode and a reference electrode. 3. The capacitance type pressure sensor according to claim 1, wherein the liquid portion has physical properties such as water absorption, evaporation and viscosity. 4. The capacitance type pressure sensor according to claim 3, wherein the first electrode or the second electrode comprises a pressure sensitive electrode and a reference electrode. 5. The capacitance type pressure sensor according to claim 3, further comprising a wiring hole provided on the fixed substrate for wiring the wirings of the first electrode and the second electrode on opposite sides. 6. The capacitance type pressure sensor according to claim 5, wherein the first electrode or the second electrode comprises a pressure sensitive electrode and a reference electrode. 7. A capacitance type pressure sensor according to claim 5, wherein one of the atmosphere hole and the wiring hole is opened to the atmosphere. 8. A fixed substrate made of an electrically insulating material having a first electrode formed on one surface, a diaphragm made of an electrically insulating elastic material having a second electrode formed on one surface, and the first electrode. And an adhesive layer in which the second electrode is disposed so as to face each other and is formed on at least one peripheral portion of the first electrode and the second electrode, and the fixed substrate and the diaphragm are joined with a minute gap therebetween. Filling the space between the diaphragm and the fixed substrate, the air hole provided in the fixed substrate, the wiring hole provided in the fixed substrate for wiring the wires of the first electrode and the second electrode on opposite sides, The capacitance type pressure sensor according to claim 5, further comprising a liquid portion having low water absorption, evaporation and viscosity. 9. The capacitance type pressure sensor according to claim 8, wherein the first electrode or the second electrode comprises a pressure sensitive electrode and a reference electrode. 10. The capacitance type pressure sensor according to claim 8, wherein either one of the air hole and the wiring hole is opened to the atmosphere. 11. The static electricity storage device according to claim 1, wherein the volume of the air holes is 0.5 to 1.5 times the volume of the portion surrounded by the fixed substrate, the diaphragm and the adhesive layer. Capacitive pressure sensor. 12. A capacitance type pressure sensor according to claim 1, a determination means for determining abnormality of the capacitance type pressure sensor based on an electric signal from the capacitance type pressure sensor, and the capacitance. Equipment whose gas pressure is detected by a pressure sensor, a flow rate detecting means for detecting a gas flow rate of the gas equipment, and an abnormality of the gas equipment by an electric signal from the capacitance type pressure sensor and the flow rate detecting means. A gas abnormality monitoring apparatus comprising: a determination unit that determines whether the gas is abnormal and an operation unit that operates according to a signal from the determination unit. 13. A capacitance type pressure sensor according to claim 3, a determination means for determining abnormality of the capacitance type pressure sensor based on an electric signal from the capacitance type pressure sensor, and the capacitance. Equipment whose gas pressure is detected by a pressure sensor, a flow rate detecting means for detecting a gas flow rate of the gas equipment, and an abnormality of the gas equipment by an electric signal from the capacitance type pressure sensor and the flow rate detecting means. A gas abnormality monitoring apparatus comprising: a determination unit that determines whether the gas is abnormal and an operation unit that operates according to a signal from the determination unit. 14. A capacitance type pressure sensor according to claim 5, a determination means for determining abnormality of the capacitance type pressure sensor based on an electric signal from the capacitance type pressure sensor, and the capacitance. Equipment whose gas pressure is detected by a pressure sensor, a flow rate detecting means for detecting a gas flow rate of the gas equipment, and an abnormality of the gas equipment by an electric signal from the capacitance type pressure sensor and the flow rate detecting means. A gas abnormality monitoring apparatus comprising: a determination unit that determines whether the gas is abnormal and an operation unit that operates according to a signal from the determination unit. 15. A capacitance type pressure sensor according to claim 8, a determination unit for determining abnormality of the capacitance type pressure sensor based on an electric signal from the capacitance type pressure sensor, and the capacitance. Equipment whose gas pressure is detected by a pressure sensor, a flow rate detecting means for detecting a gas flow rate of the gas equipment, and an abnormality of the gas equipment by an electric signal from the capacitance type pressure sensor and the flow rate detecting means. A gas abnormality monitoring apparatus comprising: a determination unit that determines whether the gas is abnormal and an operation unit that operates according to a signal from the determination unit. 16. A capacitance type pressure sensor according to claim 11, a determination means for determining abnormality of the capacitance type pressure sensor based on an electric signal from the capacitance type pressure sensor, and the capacitance. Equipment whose gas pressure is detected by a pressure sensor, a flow rate detecting means for detecting a gas flow rate of the gas equipment, and an abnormality of the gas equipment by an electric signal from the capacitance type pressure sensor and the flow rate detecting means. A gas abnormality monitoring apparatus comprising: a determination unit that determines whether the gas is abnormal and an operation unit that operates according to a signal from the determination unit.