JPH0454430Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a mobile gas leakage inspection device that detects city gas leaking from underground pipes.

[Conventional technology]

Conventionally, this type of mobile gas leak inspection equipment has
For example, there is something like the one shown in Figure 8. That is, wheels 2 for running are provided on the base 1, a collection part 3 for collecting gas that comes into sliding contact with the road surface GL is formed on the plate 4, and a suction system for sucking gas from the collection part 3 is provided on the base 1. It was equipped with a device 5, a gas detector 6, a gas concentration indicator 7, a gas suction pipe 8, etc. (see Japanese Utility Model Publication No. 13719/1983).
The collecting section 3 has a cap-shaped cross section as shown in FIG.

[Problem that the invention attempts to solve]

By the way, although the above-mentioned conventional mobile gas leakage inspection device is configured to be able to move in one direction, movement in the opposite direction is not considered at all. Therefore, when inspecting a certain range of the road surface GL back and forth, it is necessary to change the direction of the entire system, which poses a problem in that it is inconvenient to operate.

This invention was made in order to solve the above-mentioned problems, and the purpose is to obtain a mobile gas leakage inspection device with excellent operability.

[Means for solving the problem] The mobile gas leak inspection device according to this invention has the following features:
Using a hot wire semiconductor gas sensor as a gas detection device,
The cross section of the gas collection port expanded downward is formed by a hollow opening, and a plate body is provided that continues to the periphery of the opening and whose lower surface slides into contact with the road surface, and further, the base of the plate body is provided. The front and rear ends of the base in the direction of movement are curved upward and fixed to the base.

[Effect]

With this device, when inspecting for gas leaks, all you have to do is push or pull the base with wheels to either the front or back, and the gas collection ports are bent upward at both ends of the front and back, making it easy to check for gas leaks. If there is a gas leak, the gas detector detects the gas sucked up from the gas collection port.

〔Example〕

FIG. 1 is a partially cutaway side view showing an embodiment of this invention, in which 10 shows the entire mobile gas leakage inspection device, 11 is a base, 12 and 13 are wheels provided on the base 11, Reference numeral 14 denotes a gas collection port, which has a downwardly expanded cross section formed by a hollow opening 15, and is further provided with a plate 16 that continues around the opening 15 in the direction of movement of the base 11 (arrow A). The front end 16a and the rear end 16b of the plate 16 are directed upward to form curved parts 17 and 18, respectively, and both are attached to the base 11. 19 is a gas suction pipe attached to the gas collection port 14;
0 is a filter, 21 is a gas suction tube, 22 is a gas detection device, 23 is a cable, 24 is an indicator for indicating the amount of detected gas, etc., 25 is a handle, and 26 is a gripping portion.

In the mobile gas leakage inspection device 10 configured as described above, the gas collection port 14 is slid on the road surface GL, the gas collection port 14 collects the gas leaking onto the road surface GL, and the gas Suction pipe 19, filter 2
0, the gas is detected by the gas detection device 22 through the gas suction pipe 21, and the amount of gas is instructed by the indicator 24.

FIG. 2 is a partial side sectional view showing another shape of the plate body 16 of FIG. 1. FIG. In this embodiment, the plate 16
A hard material is glued to the part of the road surface that contacts the GL to improve wear resistance and improve slippage. For example, holes 27 are provided at appropriate intervals in the width direction of the plate 16, and alumina balls 2 are inserted into the holes 27.
8 is embedded and fixed with adhesive 29. According to this configuration, since the alumina balls 28 slide on the road surface GL, slippage is improved and overall operability is improved. In addition, alumina ball 28
Other balls can also be used instead.

Next, an example of a hot wire type semiconductor gas sensor used in an embodiment of this invention is shown in FIGS. 3a and 3b.

FIG. 3a is a side sectional view showing a substrate-type hot wire semiconductor gas sensor, in which a platinum film electrode 32 is formed in a meandering manner on one surface of an alumina substrate 31, a metal oxide sintered semiconductor 33 is formed thereon, and an alumina A platinum film heater 34 is provided on the other surface of the substrate 31, and is covered with a heater protective film 35.
(See Publication No. 55062).

FIG. 3b shows an example of a spherical hot-wire type semiconductor gas sensor, in which a coiled part 42 of a platinum wire 41 is embedded in a lump of S _{O 2} fine powder and sintered to form a metal oxide. A sintered semiconductor 43 is formed.

In this way, by making the S _{O 2} sintered body into fine particles, the specific surface area of the metal oxide sintered semiconductors 33, 43 can be made 50 to 300 m ² /g, which increases the sintering activity. Gases that are more flammable than methane, such as H ₂ , alcohol, CO, organic solvents (benzene/toluene), and unsaturated hydrocarbons such as ethylene, are burned on the surface layer of the sintered body to reduce the actual temperature inside the sintered layer. By making it extremely small, sensitivity to miscellaneous gases is suppressed.

FIG. 4 is a diagram showing the measurement circuit. In this figure, the hot wire semiconductor gas sensor R _S is installed in the gas passage, R ₀ , R ₁ , R ₂ are resistors, E is the power supply, VR
is a variable resistor, and V is a voltmeter.

In this way, hot wire semiconductor gas sensor R _S and 3
A bridge circuit is formed by the resistors R ₀ , R ₁ , and R ₂ , and an output voltage is obtained by a change in resistance value on the detection side due to gas adsorption to the hot wire type semiconductor gas sensor R _S and is indicated by a voltmeter V.

Fig. 5 is a block diagram of the mobile gas leakage inspection device of this invention, where the same symbols as in Fig. 1 indicate the same parts, and the output from the hot wire semiconductor gas sensor R _S is as follows:
The signal is amplified by the amplifier AMP and displayed on the indicator M, and an alarm such as a flashing lamp or buzzer or an intermittent buzzer can be issued from the display DP through the comparator COM. In addition,
PW is the power supply, PS is the constant voltage circuit, GO is the gas outlet,
P is a pump.

Figure 6 shows the FID (Flame Ionization Detector) method, and Figure 7 shows the output ratio of each gas when using a saturated hydrocarbon-selective hot-wire semiconductor gas sensor, with the output of 100 ppm methane taken as 100%. It can be seen that FIG. 7 has better saturated hydrocarbon selectivity than FIG. 6.

In other words, in Figure 6, the output of methane 100ppm is
When set to 100%, toluene, benzene, propane,
Since ethylene becomes 100% at a gas concentration of 20 to 70 ppm, malfunctions may occur when trying to detect methane, but in Figure 7, ethylene, hydrogen, benzene, alcohol, toluene, propane, acetone, and monoxide Since carbon, acetylene, etc. are extremely low compared to methane, malfunctions hardly occur.

[Effect of idea]

As explained above, this invention uses a hot-wire type semiconductor gas sensor as a gas detection device, and forms the gas collection port with a hollow mountain-shaped opening with a downwardly expanded cross section, and the periphery of the opening. Continuing with the above, a plate whose lower surface is in sliding contact with the road surface is provided, and the front and rear ends of this plate in the direction of movement of the base are curved upward and fixed to the base, so that underground construction sites can be easily Alternatively, when detecting a gas leak of city gas near the surface of a buried gas pipe, the base can be freely moved both in the advancing direction and in the opposite direction. Therefore, there is no need to change direction when inspecting a certain area of the road surface back and forth, and detection can be performed even in narrow spaces, providing excellent operability. Moreover, since it uses a hot-wire type semiconductor gas sensor, it shows the correct value even if the amount of suction is smaller than other gas sensors, so it is possible to detect leaked gas even if the periphery of the collection port sticks to the road surface. This can reduce the amount of exhaust gas suctioned, and can reduce erroneous indications due to exhaust gas. In addition, since unnecessary air is not sucked from around the collection port, it has a remarkable practical effect in that correct instructions can be obtained.

[Brief explanation of drawings]

Figure 1 is a partially cutaway side view showing an embodiment of this invention, Figure 2 is a partial side sectional view showing the shape of the plate shown in Figure 1, and Figures 3a and b are hot wires used in this invention. 4 is a block diagram showing an example of a circuit used to implement this invention, and FIG. 5 is a diagram of a mobile gas leakage inspection device of this invention. Block diagram, No. 6
The figure is a detection characteristic diagram of the FDI method, Figure 7 is a detection characteristic diagram of a hot wire semiconductor gas sensor with saturated hydrocarbon selectivity, Figure 8 is a side view showing an example of a conventional mobile gas leak inspection device, and Figure 9 FIG. 8 is a side cross-sectional view showing the shape of the collection section in FIG. 8; In the figure, 10 is a mobile gas leak inspection device, 11 is a base, 12 and 13 are wheels, 14 is a gas collection port, 1
5 is an opening, 16 is a plate, 16a is a front end, 16
b is the rear end, 17 and 18 are the curved parts, 19 and 21 are the gas suction pipes, 20 is the filter, 22 is the gas detection device, 24 is the indicator, 25 is the handle, 26 is the grip, and GL is the road surface. .

Claims (1)

[Claims for Utility Model Registration] (1) A gas collection port attached to a base with wheels is slid on the road surface, and the gas leaked onto the road surface is sucked, In a mobile gas leak inspection device that detects the gas using a gas detection device installed on a table, a hot wire semiconductor gas sensor is used as the gas detection device, and the cross section of the gas collection port expanded downward is an opening that is hollow. A plate body is provided, which extends to the periphery of the opening and has a lower surface in sliding contact with the road surface, and further, the front and rear ends of this plate body with respect to the traveling direction of the base are curved upward to form the base plate. A mobile gas leak inspection device that is fixed to a base. (2) The mobile gas leakage inspection device according to claim 1, wherein the gas collection port has a wear-resistant material embedded and fixed in the portion that comes into contact with the road surface.