JPH06229962A - Apparatus for storing gas leakage alarm - Google Patents

Abstract

PURPOSE:To obtain a gas leakage alarm which can be started easily by reducing initial rumbling time by sealing the gas leakage alarm into an airtight container along with a sealing gas with a specific steam pressure for storage. CONSTITUTION:A gas leakage alarm 12 is sealed into an airtight container 11 along with a sealing gas 16 for storage. The sealing gas 16 has a specific steam pressure. For example, a water-retention agent 13 where water is included in a gauze is stored in the airtight container 11 along with the gas leakage alarm 12. The airtight container 11 is constituted by the lamination film of polyethylene and aluminum foil with extremely low water transmission property. The opening of the airtight container 11 is airtightly sealed by a sealing machine. The mechanism for reducing an initial rumbling time is unknown but, this way, the initial rumbling time can be reduced with improved reproducibility to approximately 15 seconds, and the work time for confirming normal operation when installing the alarm 12 can be reduced. Further, a circuit for preventing initial rumbling is not needed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage device for a gas leak alarm device incorporating a gas sensor using a metal oxide semiconductor as a detector, and more particularly to a storage device for reducing the initial ringing time of the sensor of the gas leak alarm device. Regarding equipment.

[0002]

2. Description of the Related Art When a metal oxide semiconductor such as tin oxide is heated to about 200 ° C. or higher in the air, oxygen in the air is adsorbed on the surface of the particles to increase the resistance. When a flammable gas such as LP gas comes into contact with this state, this reacts with the adsorbed oxygen, and the adsorbed oxygen is desorbed from the particle surface, resulting in 1/10 of the resistance in the atmosphere
To 1/100. The presence or absence of flammable gas is detected by the change in the electric resistance value.

FIG. 6 is a perspective view showing a conventional sintering type gas sensor. Electrodes 17, 17A made of a pair of metal coils are embedded inside a detection unit 18 made of a sintered body of tin oxide. Electrode 1 consisting of a pair of metal coils
Reference numerals 7 and 17A are electrodes for detecting the electric resistance value of the detection part 18 made of a tin oxide sintered body, one of which is a sintered body.
It is also a heater for heating to 0 to 400 ° C.

FIG. 7 is a sectional view showing a conventional thick film type gas sensor. A heater 20 is formed on one of the main surfaces of the insulating substrate 19, and an electrode 21 and a detection unit 22 formed of a thick film of a metal oxide semiconductor are formed on the other main surface. A small amount of a noble metal such as platinum or palladium is added to the detection parts 18 and 22 of the above-mentioned gas sensor. This noble metal functions as a catalyst that accelerates the rate of oxygen desorption due to the adsorption of oxygen and the adsorption of flammable gas.

The heaters 17 and 20 hold the gas sensor at a temperature of 300 to 500 ° C. The adsorption of oxygen captures electrons from the metal oxide semiconductor to increase the resistance of the metal oxide semiconductor as shown in the following formula.

[0006]

Embedded image O ₂ + 2e = 2O ⁻¹ (I) Further, desorption of oxygen returns electrons to the metal oxide semiconductor as shown in the following formula to reduce the resistance of the metal oxide semiconductor.

[0007]

Embedded image 2O ⁻¹ + H ₂ = (1/2) O ₂ + H ₂ O + 2e (II) FIG. 8 is a connection diagram showing a basic circuit of a conventional gas sensor using a metal oxide semiconductor. The gas sensor 26 made of a metal oxide semiconductor is heated to a predetermined temperature by the heater 25. The change in the electric resistance value of the gas sensor 26 is detected by the voltage V _L across the fixed resistor 27 connected in series with the gas sensor 26. 23 is a power supply. A predetermined voltage is supplied to the gas sensor 26 and the heater 25 via the transformers 24 and 24A. The voltage V _L across the fixed resistor 27 is expressed by the following equation when the resistance of the gas sensor is R _s and the resistance value of the fixed resistor is R _L.

[0008]

[Number 1] _{V L = V C · R L} / (R s + R L) (1) where V _C is the voltage applied to the series to both of the fixed resistor and the gas sensor. FIG. 9 is a diagram showing an initial ringing characteristic of a conventional gas sensor. The resistance value R _{s of the} gas sensor is about 10 ³ KΩ at room temperature, but it rapidly decreases immediately after energization.
After that, it rises slowly and reaches a steady value after 30 minutes or more.

The abrupt decrease in resistance immediately after energization is due to the semiconductor property of the metal oxide semiconductor corresponding to the temperature rise of the gas sensor. Further, the subsequent increase in the gas sensor resistance value is a process in which atmospheric oxygen is adsorbed on the surface of the metal oxide semiconductor.

[0010]

FIG. 10 is a diagram showing the sensor output in the initial ringing of the conventional gas sensor.
The sensor output rises rapidly immediately after energization and then reaches a steady value. Here, if the threshold value V _T of the output at which the gas leak alarm gives an alarm is set to (1/2) V _C , the output becomes 1/2.
The above period ΔT is a ringing state for issuing an alarm, and this period is usually 1 to 3 minutes in the current gas sensor.

In this way, the ringing state for several minutes after the power is turned on cannot be avoided. However, there is a risk that the user may mistakenly think that this initial ringing is a gas leak, and current gas leak alarms use a timer circuit to prevent ringing during the period of this initial ringing, but the ringing state for several minutes There was a problem that it was too long. The present invention has been made in view of the above points, and an object thereof is to provide a gas leak alarm that can be easily started by shortening the initial ringing time.

[0012]

According to the present invention, there is provided a gas leak alarm device having a built-in sensor including a detection portion made of a metal oxide semiconductor and a heater for heating the detection portion to a predetermined temperature. The storage device of (1), which has (1) an airtight container and (2) a sealed gas, and the gastight container stores the gas leak alarm for a certain period of time by sealing the gas leak alarm without electricity. The sealed gas has a predetermined water vapor pressure and is sealed together with a gas leak alarm in the airtight container.

[0013]

[Function] Although the mechanism by which the initial ringing time is shortened is unknown,
When the above requirements are met, the initial ringing time is shortened with good reproducibility.

[0014]

Embodiments of the present invention will now be described with reference to the drawings. Embodiment 1 FIG. 1 is a layout view showing a storage device according to an embodiment of the present invention. The airtight bag 11 is made of a laminate film of polyethylene and aluminum foil, which has extremely low moisture permeability. A water retention agent 13 in which gauze is impregnated with water is stored in an airtight bag 11 together with a gas leak alarm 12. The opening of the airtight bag is hermetically sealed using a sealing machine. The gas leak alarm device was taken out of the airtight bag at every predetermined time and kept for 1 h in the atmosphere at 25 ° C. and 60% relative humidity, and then the initial ringing time was measured.

As the sensor of the gas leak alarm, tin oxide is used in the same manner as the conventional example shown in FIG. 7 to form the detection portion 22 by screen printing and firing, and the heater 20 is made of ruthenium oxide. In the detection part 22, tin oxide was loaded with 0.2% of palladium as a sensitizer. The gas sensor thus manufactured was incorporated into a gas leak alarm, and operated for 24 hours in the atmosphere at the rated value. The sensor temperature was 320 ° C. in the energized state. Fixed resistance is 15kΩ,
It was set to V _C = 5V. The gas leak alarm was then sealed in a storage device. Comparative Example For comparison, an initial ringing time was measured when a gas leak alarm manufactured in the same manner as described above was left for 24 hours after being energized in the atmosphere of 25 ° C. and 60% relative humidity without being energized.

FIG. 2 is a diagram showing an initial ringing characteristic 14 of a gas leakage alarm device stored by using the storage device according to the embodiment of the present invention, together with an initial ringing characteristic 15 of the gas leakage alarm device according to the comparative example. . It can be seen that the initial ringing time of the gas leak alarm device of the present invention is 10 to 15 s even when left for 1 month, which is shorter than the 130 to 140 s of the comparative example.

FIG. 3 is a diagram showing the initial ringing characteristics of the gas leak alarm device stored at different relative humidities using the storage device according to the embodiment of the present invention. The standing time is 30d. It can be seen that when the relative humidity is 95% or more, the initial ringing time is within 20 s even if left for 30 d. Embodiment 2 FIG. 4 is a layout view showing a storage device according to another embodiment of the present invention.

A gas leak alarm 30, a sealing gas 32 and a desiccant 34 are placed in the airtight bag 31. The airtight bag 31 is sealed at the thermocompression bonding portion 33. The desiccant is silica gel. In addition to the desiccant 34, a gas adsorbent may be used together if necessary. The gas adsorbent is activated carbon. The gas leak alarm 30 was dried in a desiccator for 30 minutes prior to sealing. Then, a gas leak alarm was fed into an airtight bag 31 made of nylon film in a container in which dry air having a dew point of −60 ° C. was flown, and the opening was thermocompression bonded at a temperature of 160 ° C.

FIG. 5 shows the initial ringing characteristic 35 of the gas leak alarm device stored using the storage device according to the embodiment of the invention shown in FIG. 4 and the initial ringing of the gas leak alarm device when the gas adsorbent is used in combination. It is a diagram which shows the characteristic 36. It can be seen that the initial ringing time is shortened when stored in dry air. Also, it can be seen that the initial ringing time is further shortened if the gas adsorbent is also used.

[0020]

According to the present invention, there is provided a storage device for a gas leak alarm device, which has a built-in sensor including a detection section made of a metal oxide semiconductor and a heater for heating the detection section to a predetermined temperature, (1) It has an airtight container and (2) a sealing gas, and the airtight container seals the gas leak alarm device without energizing and keeps the gas leak alarm device for a certain period, and the sealed gas has a predetermined water vapor pressure. Since it is assumed that it is enclosed with the gas leak alarm in the airtight container, the initial ringing time is 15
It will be a short time of about s, and the work time for confirming normal operation when installing the alarm will be greatly shortened.

Further, the gas leak alarm device does not need a prevention circuit for preventing the initial ringing, and can be used as a signal for confirming the normal operation instead. By the way, according to the inspection regulations of the gas leak alarm for liquefied gas established by the High Pressure Gas Safety Association, it is specified that the initial warning sound is generated within 2 minutes after the power is turned on. Can be completely filled.

[Brief description of drawings]

FIG. 1 is a layout view showing a storage device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an initial ringing characteristic 14 of a gas leak alarm device stored by using a storage device according to an embodiment of the present invention, together with an initial ringing characteristic 15 of a gas leak alarm device according to a comparative example.

FIG. 3 is a diagram showing an initial ringing characteristic of a gas leakage alarm device stored at different relative humidities using the storage device according to the embodiment of the present invention.

FIG. 4 is a layout view showing a storage device according to another embodiment of the present invention.

5 is an initial ringing characteristic 35 of the gas leak alarm device stored using the storage device according to the embodiment of the invention shown in FIG. 4, and an initial ringing characteristic 36 of the gas leak alarm device when a gas adsorbent is used in combination. Diagram showing

FIG. 6 is a perspective view showing a conventional sintered gas sensor.

FIG. 7 is a sectional view showing a conventional thick film type gas sensor.

FIG. 8 is a connection diagram showing a basic circuit of a conventional gas sensor.

FIG. 9 is a diagram showing an initial ringing characteristic of a conventional gas sensor.

FIG. 10 is a diagram showing a sensor output in the initial ringing of a conventional gas sensor.

[Explanation of symbols]

 11 Airtight Bag 12 Gas Leak Alarm 13 Water Retaining Agent 16 Sealing Gas 17 Coil 17A Coil 18 Detector 19 Insulation Substrate 20 Heater 21 Electrode 22 Detector 23 Power 24 Transformer 24A Transformer 25 Heater 26 Gas Sensor 27 Fixed Resistance 30 Gas Leak Alarm 31 Airtight bag 32 Sealing gas 33 Thermocompression bonding part 34 Desiccant

Front page continuation (72) Inventor Akihiko Asano 1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd.

Claims (7)

[Claims] 1. A storage device for a gas leak alarm, comprising a sensor comprising a detection part made of a metal oxide semiconductor and a heater for heating the detection part to a predetermined temperature, comprising: (1) an airtight container. And (2) a hermetically sealed gas, the hermetically sealed container hermetically seals the gas leak alarm without electricity, and stores the gas leak alarm for a certain period of time. The hermetically sealed gas has a predetermined vapor pressure and is hermetically sealed. A storage device for a gas leak alarm, characterized in that it is enclosed together with a gas leak alarm in a sex container. 2. The storage device according to claim 1, wherein the airtight container is made of at least one of an organic film and a metal film. 3. The storage device according to claim 1, wherein the sealed gas is maintained at a saturated water vapor pressure through a water retention agent. 4. The storage device according to claim 1, wherein the sealed gas is maintained at a low water vapor pressure via a desiccant. 5. The storage device according to claim 1, wherein the metal oxide semiconductor is a thick film of tin oxide. 6. The storage device according to claim 1, wherein the interfering gas is removed from the sealed gas through a gas adsorbent. 7. The storage device according to claim 6, wherein the gas adsorbent is activated carbon.