JPH0219723Y2 - - Google Patents

Description

[Detailed explanation of the idea]

This idea replaces city gas with naturally occurring methane.
This invention relates to a gas detection device that can distinguish and detect LPG, gasoline, etc. City gas is natural gas whose main component is _CH4 (13A
gases) and manufacturing gases (6A, 6B gases, etc.) whose main components are CH ₄ , H _{2 ,} etc. Discrimination between natural gas and naturally occurring methane will be described below, but the same applies to discrimination between manufactured gas and naturally occurring methane. In the case of natural gas, the main component is methane, and gas leak detection for natural gas is performed using a methane gas sensor. However, in many cases, naturally occurring methane is detected and misidentified as a city gas leak, resulting in unnecessary road surface excavation, which results in a lot of wasted labor and money. This idea was developed in consideration of the above points, and is a first method that is sensitive to flammable gases including methane.
Using a gas sensor and a second gas sensor sensitive to combustible gases other than methane, each independent gas concentration indicator indicates the concentration, and by comparing the readings of both indicators, it is possible to determine whether natural gas or
In addition to being able to determine whether the gas is naturally occurring methane, LPG, or gasoline,
When natural gas is detected, an alarm is emitted by a lamp or buzzer. This idea will be explained below with reference to the drawings. FIG. 1 is a block diagram of a gas and electric circuit showing one embodiment of this invention. In this figure, 1 is a gas intake port, 2 is a gas discharge port, and a flow path 3 communicates between them. A first gas sensor 4 is sensitive to flammable gases including methane. A second gas sensor 5 is sensitive to combustible gases other than methane. These first and second gas sensors 4 and 5 can be constructed by using catalytic combustion type gas detection elements and heating them at different temperatures. For example, the first gas sensor 4, which detects flammable gases including methane, is set at 400°C or higher, and the second gas sensor 5 is set at 200-300°C. 6 is a pump, and these 4 to 6 are inserted in series into the flow path 3. 7 and 8 are amplifiers to which the outputs of the first and second gas sensors 4 and 5 are added, respectively;
9 and 10 are zero adjusters for the amplifiers 7 and 8, respectively; 11 and 12 are gas concentration indicators;
The gas concentration is indicated by the gas sensors 4 and 5, both of which are calibrated using city gas. 13,14,1
5 and 16 are comparators, 17 is a NAND circuit, and the comparator 13 compares the magnitude of the outputs of the amplifiers 7 and 8, and the output M of the amplifier 7 and the output S of the amplifier 8 are S/M≦1/4. , that is, an output of "0" is output when naturally occurring methane is generated. The comparator 14 outputs "L" when S/M≧4, that is, gasoline and LPG. The comparator 15 compares the output of the second gas sensor 5 with a predetermined level to see if it is extremely small, and if it is smaller than the predetermined level, it determines that it is in the noise area and outputs "L". The outputs of the comparators 13, 14, and 15 are applied to the NAND circuit 17, and the outputs of the comparators 1
Added to 6. 3 comparators 13,1
When all three of the outputs 4 and 15 are "H", the output of the NAND circuit 17 becomes "L", and the output of the comparator 16 also becomes "L". Then, any one of the three comparators 13, 14, 15
When the outputs of the NAND circuit 17 and the comparator 16 are "L", the outputs of the NAND circuit 17 and the comparator 16 become "H". 18 is an indicator lamp, which lights up when the output of the comparator 16 is "L", that is, when the outputs of the amplifiers 7 and 8 are 1/4<S/M<4, indicating that city gas is being detected. inform. 19 and 20 are also indicator lamps, and the indicator lamp 19 lights up when the output M of the amplifier 7 and the output S of the amplifier 8 are S/M≦1/4, that is, natural methane, and the indicator lamp 20 lights up when the output M of the amplifier 7 and the output S of the amplifier 8 are S/M≦1/4, that is, natural methane. In other words, it lights up and displays when it is gasoline or LPG.
21 is a power supply, 22 is a constant voltage circuit, and 23 is an indicator lamp, which indicates that the power supply 21 is on. 24 is a changeover switch. Next, the effect will be explained. When the test gas is sucked through the gas intake port 1 by the pump 6, the test gas passes through the first and second gas sensors 4 and 5 and is discharged from the gas discharge port 2.
The outputs of these first and second gas sensors 4 and 5 are:
It is amplified by amplifiers 7 and 8 and indicated by gas concentration indicators 11 and 12, respectively. In this case, the first
The characteristics of the second gas sensors 4 and 5 with respect to various gases are shown in FIGS. 2, 3, and 4. Figure 2 shows natural methane (pure methane) concentration indicating characteristics, with the full scale being 100 and shown on the vertical axis, and the horizontal axis showing concentration (%) and LEL (%). The curve is the indication characteristic of the gas concentration indicator 11, and the curve is the indication characteristic of the gas concentration indicator 12. FIG. 3 similarly shows the case of supply gas, for example 13A gas (natural gas system), and FIG. 4 similarly shows the case of gasoline. As you can see, the gas concentration indicator 11,
What kind of gas it is can be determined from the combination of 12 instructions. If this is displayed, it will look like Table 1 below. In this way, the type of detected gas can be determined from the gas concentration indicators 11 and 12. The gas concentration indicators 11 and 12 are placed side by side on the same panel surface so that the deflections of the pointers of the gas concentration indicators 11 and 12 can be easily compared. An example is shown in FIG. Figure 5 shows an example of the panel surface, and each symbol indicates the first
It corresponds to the figure. Such an arrangement facilitates the determination in Table 1 described above.

[Table] The same concept can be applied to manufactured gas. As explained in detail above, this invention uses a first gas sensor that is sensitive to flammable gases including methane and a second gas sensor that is sensitive to flammable gases other than methane, and calculates the outputs of these sensors, respectively. At the same time, both gas concentration indicators are installed side by side on the same panel surface, and the indications of the gas concentration indicators are compared, and from the ratio of the two, it is determined whether the gas being tested is city gas, natural methane, gasoline, or We have provided an identification means for detecting LPG, and a display means that is activated by the output of this identification means and displays that the gas to be tested is city gas, natural methane, gasoline, or LPG. By looking at the display and determining whether it is natural methane, gasoline, or LPG, the content of the sample gas can be intuitively estimated, and whether the sample gas is on the boundary between the three gas types. Even in such cases, accidents can be prevented by determining the type of gas. Therefore, unlike the conventional method, there is no risk of misidentifying naturally occurring methane and city gas, and there is an advantage that proper gas detection can be performed.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a gas and electric circuit showing an embodiment of this invention, Figs. 2, 3, and 4 are indication characteristic diagrams for various gases of the gas concentration indicator of this invention, and Fig. 5. FIG. 1 is a plan view showing an example of a panel of this invention. In the figure, 1 is a gas intake port, 2 is a gas outlet port, 3 is a flow path, 4 is a first gas sensor, 5 is a second gas sensor, 6 is a pump, 7 and 8 are amplifiers, and 9 and 10 are zero adjustments. 11, 12 are gas concentration indicators, 13~
16 is a comparator, 17 is a NAND circuit, 18~
20 is a display lamp.

Claims (1)

[Scope of utility model registration request] A first gas sensor that is sensitive to flammable gases including methane, a second gas sensor that is sensitive to flammable gases other than methane, and first and second gas sensors that display the outputs of the first and second gas sensors, respectively. 2 gas concentration indicators are provided, and these gas concentration indicators are installed side by side on the same panel surface, and furthermore, the gas concentration indicator indicates the gas concentration indicator based on the output of the first gas sensor, and the gas concentration indicates the gas concentration indicator based on the output of the second gas sensor. an identification means for detecting whether the gas to be tested is city gas, natural methane, gasoline, or LPG based on the ratio of the indications on the indicator; 1. An identification type gas detection device characterized by being provided with a display means for indicating whether the gas is gasoline or LPG.