JPH0210451Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention is designed to determine whether, for example, gas generated at underground construction sites is supply gas (generally referred to as city gas) or pure methane gas naturally generated from underground. Alternatively, the present invention relates to a device for identifying propane gas or gasoline using a catalytic combustion type gas detection element that utilizes a platinum metal catalyst such as platinum palladium.

A conventionally known device of this type involves adjusting the current flowing through the gas detection element through a variable resistor connected in series with the power supply to limit the temperature rise range due to heating of this element to 150°C. By setting and maintaining the temperature at ~250°C, the element responds only to hydrogen and carbon monoxide in the supplied gas, but not to methane, thereby preventing misidentification with naturally occurring methane gas. Some devices are configured to detect the presence or absence of leakage of supply gas. However, such conventional devices can only detect the presence or absence of a leak in the supplied gas, and cannot detect the presence or absence of naturally occurring methane gas or propane gas when detecting the leak.

If we were to use the above-mentioned conventional device to detect the presence or absence of naturally occurring methane gas, the temperature range due to heating of the gas detection element would have an upper limit of 400°C or higher and a lower limit of 150°C to 150°C. It is necessary to make adjustments at least twice over a range of 250°C, perform detection work two or more times, and identify the gas from the results of the multiple work. Not only is the work efficiency very poor, but it is also easy to misidentify due to the effect of changes in gas concentration over time, and it is difficult to compare outputs because it is necessary to read a single indicator. There was a problem.

In view of these circumstances, the present invention has been developed to reliably, accurately, and accurately identify the type of gas present through only one detection operation.
The purpose is to provide a device that is easy to perform.

The gas identification device according to the present invention, which was developed with the above purpose in mind, connects a catalytic combustion type gas detection element that can be maintained at a temperature of 400°C or higher via a variable resistor connected in series with a power source to the first bridge circuit. A temperature compensation element is connected to the resistance side of the first bridge circuit, and an indicator is connected to the output side of the first bridge circuit. In addition to configuring a gas detection device, a catalytic combustion gas detection element that can be maintained at a temperature of 150°C to 250°C is installed on the measured side of the second bridge circuit via a variable resistor connected in series with the power supply. ,
Further, a temperature compensating element is connected to each resistance side of the second bridge circuit, and an indicator is connected to the output side of the second bridge circuit to configure a device that detects only non-methane combustible gas. It is characterized by certain things.

To summarize, the device of the present invention has two types: one that responds to all combustible gases including methane by setting the temperature increase range due to heating to 400℃ or higher;
Two catalytic combustion gas detection elements, one set at 150°C to 250°C and responsive only to non-methane combustible gases, are used to simultaneously detect the gas present, and each is connected via a separate bridge circuit. By simultaneously indicating the detected values, it is possible to identify whether the existing gas is leaking gas from the supply gas pipe or naturally occurring methane gas from the output difference (=indicated value) caused by the methane content rate. Because of this, the detection work only needs to be done once, which not only significantly improves work efficiency and significantly simplifies the work effort compared to the conventional devices mentioned above, but also prevents misunderstandings caused by changes in gas concentration over time. There are no mistakes caused by comparing multiple detected values, and the desired type of gas can be identified reliably, accurately, and easily.This type of device is capable of detecting leaks of supplied gas. In addition, it has a wide range of uses, such as detecting the presence or absence of natural generation of methane gas, and detecting the presence or absence of propane or gasoline leaks, making it extremely useful in practice.

The embodiments of the present invention will be described below in detail based on the drawings. In the drawings, reference numerals 3 and 8 indicate a porous wire mainly composed of alumina, silica, etc. Carrier 13
This is a catalytic combustion type gas detection element which is constructed by covering the gas detection element 3 with a platinum metal catalyst 14 such as platinum palladium on it, and 4 and 9 are the gas detection element 3,
This is a temperature compensation element in which a porous carrier 13' covers a hot wire 12' having the same material and shape as 8, and these gas detection elements 3 and 8 and temperature compensation elements 4 and 9 are connected to a DC power supply 1. The proportional resistance sides 15 and 16 of the first and second bridge circuits 5 and 10 are connected to the measured sides and resistance sides of the first and second bridge circuits 5 and 10 connected in parallel, respectively.
and a variable resistor 19 at each connection point of 17 and 18.
and 20, and between the sliding contacts of these variable resistors 19 and 20 and the connection points of each gas detection element 3 and 8 and each temperature compensation element 4 and 9, that is, each bridge circuit 5 and Indicators 6 and 11 such as meters are connected to the output side of 10, and the gas detection element 3 and temperature compensation element 4 are connected to the bridge circuits 5 and 10 and the DC power supply 1, respectively. Variable resistor 2 for adjusting the element temperature to set and maintain the temperature rise above 400℃,
and the gas detection element 8 and the temperature compensation element 9.
A variable resistor 7 for adjusting the element temperature is connected in series to maintain the set temperature within the rising temperature range of 150°C to 250°C.
The first bridge circuit 5 and the indicator 6 are the main components, and the second bridge circuit 10 and the indicator 11 are the main components, and the device detects all combustible gases including methane. This device is configured to operate separately from a device that detects only sexual gases.

Next, the operation and identification procedure of the gas identification device configured as described above will be explained. The gas detection elements 3 and 8 are used in places where gas is generated or where gas is likely to be generated, such as an underground construction site.
When the generated gas comes into contact with the gas detection elements 3 and 8, catalytic combustion occurs due to the catalytic action of the platinum metal catalyst 14 such as platinum/palladium attached to the surfaces of the gas detection elements 3 and 8, and the gas is detected by the heat of the combustion reaction. The elements 3 and 8 are heated and the temperature rises, and the electrical resistance of the gas detection elements 3 and 8 changes with the temperature rise, and this change in resistance value is taken out to the output side of the bridge circuits 5 and 10. This is displayed on indicators 6 and 11,
At this time, one gas detection element 3 operates due to the presence of all combustible gases including methane, while the other gas detection element 8 operates only due to the presence of combustible gases other than methane. Therefore, the output standards to both indicators 6 and 11 should be adjusted in advance so that if the output of methane gas is M and the output of non-methane gas is S, then M = S only in the case of supplied gas. According to the output difference caused by the methane content in various gases, if M>S, it is naturally occurring methane gas, if M=S, it is supply gas, and if M<S, it is propane gas or gasoline. We can now identify the type of gas present.

In addition, the indicators 6 and 11 in the device of the present invention may be constructed as separate bodies, or the main body may be shared, and only the pointers may be configured to operate separately.

Furthermore, the gas detection elements 3 and 8 may be made of a platinum metal catalyst such as platinum palladium or may be made of a semiconductor.

Further, in the above embodiment, the first and second bridge circuits 5 and 10 share a power source, but separate power sources may be used.

[Brief explanation of the drawing]

The drawing is an electrical connection diagram showing an embodiment of the gas identification device according to the present invention. 1...Power supply, 2,7...Variable resistor, 3,8...
...Gas detection element, 4,9...Temperature compensation element, 5,
10...Bridge circuit, 6,11...Indicator.

Claims (1)

[Claims for Utility Model Registration] A catalytic combustion type gas detection element 3 that can be maintained at a temperature of 400°C or higher via a variable resistor 2 connected in series with a power supply 1 is attached to the side to be measured of the first bridge circuit 5. , temperature compensation elements 4 are connected to the resistance sides of the first bridge circuit 5, and
An indicator 6 is connected to the output side of the bridge circuit 5 to configure a device for detecting all combustible gases including methane, and a variable resistor 7 connected in series with the power supply 1 is used to A catalytic combustion gas detection element 8 that can be maintained at a temperature of 250° C. is connected to the measured side of the second bridge circuit 10, and a temperature compensation element 9 is connected to the resistance side of the second bridge circuit 10, and A gas identification device characterized in that an indicator 11 is connected to the output side of the second bridge circuit 10 to constitute a device that detects only non-methane combustible gas. The dual catalytic combustion type gas detection elements 3 and 8 are formed by covering the hot wire 12 with a carrier 13 and depositing a platinum metal catalyst 14 on the carrier 13. Gas identification device.