Gas detector

Abstract

To provide a gas detector with which, which includes a housing and enables increase of the size of the housing to be suppressed and enables complexing of housing structure to be suppressed, even when functions for protecting an upstream gas detection unit and a downstream gas detection unit by an elongated unit are installed.SOLUTION: This gas detector 100 comprises: a gas introduction unit 10 for introducing detection target gas 1; a housing 20 having a gas inlet 21 to which the gas introduction unit 10 is connected, and an exhaust port 22; and a control unit 30. The gas introduction unit 10 includes a first gas detection unit 11 for detecting the detection target gas 1, and an elongated unit 12 which is located at a position closer to the other end side than the first gas detection unit 11, and causes the arrival of the detection target gas 1 sent from the first gas detection unit 11 to the gas inlet 21 to be delayed. The housing 20 houses a gas flow passage 24 that connects the gas inlet 21 and the exhaust port 22 to each other, and a second gas detection unit 25 which is located in the gas flow passage 24, and which detects the detection target gas 1. The control unit 30 performs control to protect the second gas detection unit 25 according to the detection results of the first gas detection unit 11.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas detector. [Background technology]

[0002] BACKGROUND ART Conventionally, gas detectors having a function for protecting a gas detection section from high-concentration gases are known (see, for example, Patent Document 1).

[0003] The above-mentioned Patent Document 1 discloses a gas detection device in which a protection mechanism is provided between the front gas detection element and the main gas detection element. If the main gas detection element is exposed to a high concentration gas while receiving power and in a detection state, the element will deteriorate (detection accuracy will decrease). Therefore, the protection mechanism has a structure that delays the arrival of gas, such as a long section or a large-diameter buffer section, and is provided to ensure that there is enough time between when the front gas detection element detects a high concentration gas and when that high concentration gas reaches the main gas detection element. The gas detection device is configured so that when the upstream front gas detection element detects a high concentration gas, the downstream main gas detection element will not detect the high concentration gas. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-281194 Summary of the Invention [Problem to be solved by the invention]

[0005] Although not explicitly stated in Patent Document 1, the entire fluid circuit, including the front gas detection element, main gas detection element, and protection mechanism, is typically housed within the housing of a gas detection device. Furthermore, a long tube may be connected to the housing of a gas detection device for sampling air containing the target gas that is located away from the housing. The protection mechanism has a large volume, including a long section and a large-diameter buffer section, so the housing becomes large to accommodate the protection mechanism. Furthermore, the provision of a long tube increases the overall size of the gas detection device, making it difficult to carry. Another problem is that the housing structure becomes complex due to the need to accommodate the front gas detection element, main gas detection element, and protection mechanism.

[0006] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a gas detector that can prevent the housing from becoming large and the housing structure from becoming complex, even when a function to protect the downstream gas detection section is provided by the upstream gas detection section and the elongated section. [Means for solving the problem]

[0007] A gas detector according to a first aspect of the present invention comprises: , covered The gas introduction section has one end for introducing a detection gas and the other end for discharging the detectable gas, a housing having a gas inlet and an exhaust port to which the other end of the gas introduction section is connected, and control means for controlling the detection operation of the detectable gas, wherein the gas introduction section includes a first gas detection section that detects the detectable gas introduced into the gas introduction section, and a long section that is located on the other end side of the first gas detection section and causes a delay in the arrival of the detectable gas sent from the first gas detection section to the gas inlet, the housing contains a gas flow path connecting the gas inlet and the exhaust port, and a second gas detection section that is located in the gas flow path and detects the detectable gas, and the control means is configured to control the protection of the second gas detection section in accordance with the detection result of the first gas detection section, and the control means is contained within the housing, and the long section includes a flow path for circulating the detectable gas, and an electric wire that electrically connects the first gas detection section and the control means. Here, the "long portion" refers to a portion where the path length of the flow channel is increased. The first aspect of this invention2 The gas detector according to this aspect comprises a gas introduction section having one end for introducing a detectable gas and the other end for discharging the detectable gas, a housing having a gas inlet to which the other end of the gas introduction section is connected and an exhaust port, and control means for controlling the detection operation of the detectable gas, wherein the gas introduction section includes a first gas detection section for detecting the detectable gas introduced into the gas introduction section, and a long section that is arranged on the other end side of the first gas detection section and causes a delay in arrival of the detectable gas sent from the first gas detection section to the gas inlet, and the housing has a gas flow path connecting the gas inlet and the exhaust port, and a second gas detection unit disposed in the gas flow path and detecting the gas to be detected, and the control means is configured to control protection of the second gas detection unit according to the detection result of the first gas detection unit, the gas introduction unit includes a probe provided at the tip of the gas introduction unit and having the first gas detection unit, the long portion includes a flexible tube connecting the gas inlet of the housing to the probe, and the probe further includes a pump and a power supply unit for circulating the gas to be detected, and is configured to be able to perform gas detection separately from the housing by being separated from the flexible tube.

[0008] The first aspect of this invention and No. 2 In the gas detector according to this aspect, as described above, in a configuration in which protection of the second gas detector is controlled in accordance with the detection result of the first gas detector, the first gas detector and the elongated portion are provided in a gas inlet outside the housing, eliminating the need to accommodate the first gas detector and the elongated portion within the housing. Therefore, even when a long portion is provided long enough to ensure the time between when a high concentration of detectable gas is detected by the first gas detector and when it reaches the second gas detector, the housing can be prevented from becoming large. Furthermore, since the first gas detector and the elongated portion do not need to be accommodated in the housing, the housing structure can be simplified. As a result, even when the upstream first gas detector and the elongated portion are provided with the function of protecting the downstream second gas detector, the housing can be prevented from becoming large and complex. Furthermore, since the elongated portion for collecting air containing the target gas present at a location distant from the housing also serves the function of protecting the second gas detector, the gas detector can be prevented from becoming large and complex in size.

[0009] The above item 1 In the gas detector according to the above aspect, the control means is accommodated in the housing, and the long portion includes a flow path for circulating the detectable gas and an electric wire that electrically connects the first gas detection unit and the control means. With this configuration, there is no need to separately connect the flow path and the electric wire between the gas inlet portion in which the first gas detection unit is provided and the housing in which the control means is accommodated, and the flow path and the electric wire can be integrated into the long portion, thereby simplifying the device configuration.

[0010] The above item 1 of In the gas detector according to this aspect, the first gas detection unit preferably includes an optical gas detection element or a gas thermal conduction gas detection element. This configuration allows the first gas detection unit to be provided with a gas detection element that is highly resistant to high-concentration gases (i.e., that is less susceptible to deterioration even when exposed to high-concentration gases). An optical gas detection element is a gas detection element that utilizes optical properties, such as the gas's specific absorption wavelength characteristics, for gas detection, while a gas thermal conduction gas detection element is a gas detection element that utilizes the physical property of gas, namely, thermal conduction, for gas detection. Therefore, these gas detection elements do not involve chemical or catalytic reactions in gas detection, and are therefore less susceptible to deterioration and more resistant to high-concentration gases.

[0011] The above item 1 ofIn the gas detector according to this aspect, the gas introduction section preferably includes a probe provided at the tip of the gas introduction section and having a first gas detection section, and the long section includes a flexible tube connecting the probe to a gas inlet of the housing. With this configuration, an extension attachment including the probe and the flexible tube for sampling air containing the target gas present at a location away from the housing can be provided with the function of the gas introduction section. That is, by providing the first gas detection section on the probe, the probe can be configured not only as a gas introduction tube but also as a housing for housing the first gas detection section. Furthermore, the flexible tube for extending the movement range of the probe can be configured as a long section for generating a delay in the arrival of the gas at the second gas detection section. This effectively prevents the overall size of the gas detector from increasing compared to when the housing for the first gas detection section and the long section are provided separately from the extension attachment including the probe and the flexible tube.

[0012] The above item 2 In the gas detector according to the above aspect, the probe further includes a pump for circulating the gas to be detected and a power supply unit, and is configured to be able to perform gas detection separately from the flexible tube and the housing. By configuring the probe in this manner, the probe can be separated from the flexible tube and the housing by utilizing the first gas detection unit, and the probe alone can function as a simple gas detector. This makes it possible to selectively use the probe alone (only the first gas detection unit) to perform gas detection, and to connect the probe to the flexible tube and perform gas detection using both the first gas detection unit and the second gas detection unit.

[0013] Above No. 1 and No. 2In the gas detector according to this aspect, preferably, the first gas detection section and the second gas detection section have different sensitivity characteristics to the detectable gas, and the second gas detection section has a gas detection element with lower resistance to high-concentration gases than the first gas detection section. With this configuration, protection control of the second gas detection section is performed in accordance with the detection result of the first gas detection section until the gas whose arrival has been delayed by the elongated section reaches the second gas detection section, thereby making it possible to protect the gas detection element with lower resistance to high-concentration gases than the first gas detection section from deterioration due to high-concentration gases. [Effects of the Invention]

[0014] According to the present invention, as described above, it is possible to provide a gas detector that can prevent the housing from becoming large and the housing structure from becoming complex, even when the upstream gas detection section and the long section are provided with a function to protect the downstream gas detection section. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic perspective view showing the overall configuration of a gas detector; [Figure 2] 1 is a schematic diagram showing the configuration of a gas detector involved in the flow of a gas to be detected; [Figure 3] FIG. 2 is a block diagram showing a configuration related to control of the gas detector. [Figure 4] FIG. 2 is a schematic cross-sectional view of a flexible tube for explaining the structure of the flexible tube. [Figure 5] FIG. 10 is a diagram for explaining a process for protecting the second gas detection unit. [Figure 6] FIG. 4 is a flowchart for explaining the flow of operational control of the gas detector. [Figure 7] FIG. 10 is a block diagram illustrating the configuration of a gas detector according to a second embodiment. [Figure 8] 1A and 1B are diagrams for explaining a first detection mode (A) and a second detection mode (B). [Figure 9] FIG. 10 is a schematic perspective view showing the probe when operating in a second detection mode. [Figure 10] FIG. 10 is a schematic perspective view showing a modified example of the probe according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

[0017] [First embodiment] The configuration of a gas detector 100 according to a first embodiment will be described with reference to FIGS.

[0018] (Overall configuration of gas detector) Gas detector 100 is a gas detector that detects detectable gas 1. Gas detector 100 samples air present at a test location and detects the concentration of detectable gas 1 contained in the sampled air. The detectable gas is the gas that gas detector 100 is to detect.

[0019] 1, gas detector 100 includes gas introduction section 10, housing 20, and control section 30 (see FIG. 2). Note that control section 30 is an example of the "control means" in the claims.

[0020] The gas introduction section 10 has one end for introducing the detectable gas 1 and the other end for discharging the detectable gas 1. The gas introduction section 10 is capable of taking in air from one end into the gas introduction section 10, circulating the taken-in air, and discharging it from the other end. The gas introduction section 10 is configured to be detachable from the housing 20. When connected to the gas inlet 21 of the housing 20, the gas introduction section 10 is configured as an extension accessory for sampling air at an inspection location remote from the housing 20 and introducing it into the housing 20. The gas introduction section 10 includes at least a first gas detection section 11 and an elongated section 12.

[0021] The first gas detection unit 11 is configured to detect the detectable gas 1 introduced into the gas inlet unit 10. The first gas detection unit 11 is configured to detect the detectable gas 1 contained in the sampled air taken into the gas inlet unit 10 and to generate a signal corresponding to the concentration of the detectable gas 1. In the first embodiment, the first gas detection unit 11 is provided in the probe 13.

[0022] The elongated portion 12 is disposed on the other end side (housing 20 side) of the first gas detection unit 11 in the gas introduction unit 10. The elongated portion 12 is configured to connect the first gas detection unit 11 and the gas inlet 21 of the housing 20.

[0023] The long section 12 is configured to delay the arrival of the detectable gas 1 sent from the first gas detection section 11 to the gas inlet 21. The long section is a section where the path length between the first gas detection section 11 and the second gas detection section 25 is made longer (than the length originally required). In the first embodiment, the long section 12 is configured by a flexible tube 14.

[0024] The housing 20 is the exterior of the gas detector 100. In the configuration example of Fig. 1, the housing 20 has a roughly rectangular parallelepiped shape. The housing 20 includes a top surface, a bottom surface, and four side surfaces: the front side, the rear side, the right side, and the left side.

[0025] The housing 20 has a gas inlet 21 to which the other end of the gas introduction part 10 is connected, and an exhaust port 22. The gas inlet 21 is provided in a connector part 23 that protrudes from the surface of the housing 20 to the outside of the housing 20. The gas inlet 21 is an opening formed in the housing 20 (connector part 23). When the connector part 23 and the other end of the gas introduction part 10 engage with each other, the internal space of the gas introduction part 10 and the gas inlet 21 communicate with each other.

[0026] The exhaust port 22 opens on the surface of the housing 20. In the configuration example of FIG. 1, the exhaust port 22 is formed on the side surface of the housing 20. The exhaust port 22 may open on any surface of the housing 20.

[0027] The gas detector 100 shown in FIG. 1 is not a handheld type, but a portable, simple fixed type gas detector. The simple fixed type gas detector 100 is configured so that a user can carry it using a strap belt (not shown) or the like, set it up near an inspection location, and then extend the gas introduction section 10 to the inspection location to perform a gas inspection. The inspection location may be, for example, an underground buried pipe (gas pipe). Note that a handheld type is a small gas detector that can be used by a user holding the gas detector in their hand (or by attaching it to clothing, etc.).

[0028] Housing 20 has a space formed therein for accommodating each component of gas detector 100. As shown in Fig. 2, housing 20 accommodates gas flow path 24 connecting gas inlet 21 and exhaust port 22, and second gas detector 25. In this embodiment, controller 30 is also accommodated within housing 20.

[0029] (Detailed structure of gas detector) 1 and 2, the gas introduction section 10 includes a probe 13 that is provided at the tip of the gas introduction section 10 and has a first gas detection section 11. The long section 12 is formed of a flexible tube 14 that connects the gas inlet 21 of the housing 20 to the probe 13. In the first embodiment, the gas introduction section 10 further includes a pump 15.

[0030] The probe 13 has a tubular pipe 13a of a predetermined length provided at its tip and a cylindrical housing 13b connected to the pipe 13a. The pipe 13a is made of a hard material such as metal. The housing 13b houses the first gas detection unit 11 and a pump 15. The housing 13b has the pipe 13a at one end and a connector at the other end that connects to the tip of the flexible tube 14. As shown in FIG. 2, the housing 13b has a connection port 13e to the pipe 13a and a connection port 13f to the flexible tube 14. A flow path 13d is formed inside the housing 13b, connecting the connection port 13e to the connection port 13f. The first gas detection unit 11 and the pump 15 are disposed in the flow path 13d. As shown in FIG. 1, the housing 13b has a cylindrical shape and a grip 13c on the outer surface of the cylinder for a user to hold with their hand.

[0031] 2, pump 15 is configured to suck detectable gas 1 from the tip of pipe 13a into probe 13 and send it downstream. There are no particular limitations on the type and structure of pump 15. Detectable gas 1 sent out from pump 15 passes through long section 12 (flexible tube 14), gas inlet 21, second gas detection section 25, and is sent out to exhaust port 22.

[0032] The first gas detection unit 11 is configured to detect the detectable gas 1 introduced into the gas inlet 10. The first gas detection unit 11 of the first embodiment has an optical gas detection element or a gas thermal conduction gas detection element. The optical gas detection element is, for example, an NDIR (Non Dispersive Infrared) detection element. The NDIR detection element is a gas detection element that includes an infrared light source and a light receiving unit and detects the detectable gas 1 based on differences in absorbance depending on the infrared absorption characteristics of gas molecules. The gas thermal conduction gas detection element is a gas detection element that includes a heating element (resistor) coated with an inert material and detects the detectable gas 1 based on differences in temperature change of the heating element depending on the thermal conductivity of the gas.

[0033] Flexible tube 14 is a hollow, long tubular member made of a flexible resin material. Flexible tube 14 (see FIG. 1) has a connector at one end that connects to probe 13 (connection port 13f of storage portion 13b) and a connector at the other end that connects to connector portion 23 (gas inlet 21) of housing 20. Flexible tube 14 is detachably connected to probe 13 and connector portion 23 of housing 20 by engaging and disengaging the connectors. When gas detector 100 is not in use, probe 13 and flexible tube 14 can be separated from housing 20, allowing probe 13, flexible tube 14, and housing 20 to be stored compactly.

[0034] Next, the internal configuration of the housing 20 will be described.

[0035] The gas flow path 24 connects the gas inlet 21 and the exhaust port 22. The gas flow path 24 has a tubular internal space for circulating gas, and is configured by a combination of tubular members (gas tubes, pipes, etc.). One end (upstream end) of the gas flow path 24 is connected to the gas inlet 21, and the other end (downstream end) is connected to the exhaust port 22.

[0036] The second gas detection unit 25 is disposed in the gas flow path 24. The second gas detection unit 25 is configured to detect the detectable gas 1 introduced into the gas flow path 24. The second gas detection unit 25 is disposed at a position in the gas flow path downstream of the first gas detection unit 11 and the long portion 12. The gas flow path is the entire path through which the detectable gas 1 flows in the gas detector 100, from one end of the gas introduction unit 10 (the tip of the pipe 13a) to the exhaust port 22 at the other end of the gas flow path 24.

[0037] The first gas detection unit 11 and the second gas detection unit 25 have different sensitivity characteristics to the detectable gas 1. The second gas detection unit 25 has a higher sensitivity to the detectable gas 1 than the first gas detection unit 11. The lower limit of the measurable concentration range of the detectable gas 1 that the second gas detection unit 25 can detect is lower than the lower limit of the measurable concentration range of the detectable gas 1 that the first gas detection unit 11 can detect.

[0038] As an example, in the first embodiment, the detectable gas 1 is a fuel gas. The first gas detection unit 11 detects VOL concentration values ​​in a measurement concentration range of 0% VOL to 100% VOL. The second gas detection unit 25 detects LEL concentration values ​​in a measurement concentration range of 0% LEL to 100% LEL. LEL is an abbreviation for Lower Explosive Limit, and 100% LEL is the lower explosive limit concentration value for that gas type. The VOL concentration value is a value that indicates the proportion (volume ratio) of the detectable gas 1 per unit volume as a percentage. Depending on the gas type, 100% LEL is approximately a few % VOL.

[0039] The second gas detection unit 25 is composed of a gas detection element. Upon contact with the detectable gas 1, the gas detection element outputs a signal corresponding to the concentration of the detectable gas 1. There are no particular limitations on the type of gas detection element, but the second gas detection unit 25 has a gas detection element that is less resistant to high-concentration gases than the first gas detection unit 11.

[0040] The gas detection element used in the second gas detection section 25 may be, for example, a catalytic combustion type gas detection element, a hot wire semiconductor type gas detection element, or an adsorption effect transistor (AET) type gas detection element.

[0041] As an example, in the first embodiment, the second gas detection unit 25 is configured as a catalytic combustion gas detection element. The catalytic combustion gas detection element has a structure in which a sensitive layer made of a metal oxide carrying a combustion catalyst is provided on a precious metal wire coil that constitutes a heater electrode. When the sensitive layer of the catalytic combustion gas detection element is heated to its operating temperature by electrical heating and comes into contact with the detectable gas 1, catalytic combustion of the detectable gas 1 occurs due to catalytic action, and the electrical resistance value of the element changes due to the temperature change that accompanies the catalytic combustion. This change in electrical resistance value is obtained by the control unit 30 as an output signal corresponding to the gas concentration via a detection circuit (not shown).

[0042] (Control system) 3, gas detector 100 includes, in addition to control unit 30 described above, memory unit 31, power supply unit 32, alarm unit 33, display unit 34, and operation unit 35. Control unit 30, memory unit 31, power supply unit 32, alarm unit 33, display unit 34, and operation unit 35 are housed in housing 20.

[0043] The control unit 30 includes a processor such as a CPU. The storage unit 31 is composed of semiconductor storage elements and the like. The control unit 30 (processor) executes an operating program stored in the storage unit 31 to function as a control unit that controls the entire gas detector 100. The control unit 30 controls the operation of the pump 15. The control unit 30 controls the detection operations of the first gas detection unit 11 and the second gas detection unit 25. The control unit 30 controls the activation of the gas detection units by energizing the first gas detection unit 11 and the second gas detection unit 25 at gas detection timings. The control unit 30 then obtains the output of the gas detection unit in the activated state as the gas detection result. The control unit 30 also controls the deactivation of the gas detection units by not energizing the first gas detection unit 11 and the second gas detection unit 25 at times other than gas detection timings.

[0044] The memory unit 31 stores the program, as well as setting information for the gas detector 100 and history information on gas detection results. The power supply unit 32 supplies power to each unit of the gas detector 100 (the control unit 30, the memory unit 31, the notification unit 33, the display unit 34, the operation unit 35, the pump 15, the first gas detection unit 11, and the second gas detection unit 25). The gas detector 100 of the first embodiment is battery-powered, and the power supply unit 32 is composed of a battery and a power supply circuit. The power supply unit 32 may also be connectable to an external commercial power source or the like.

[0045] The notification unit 33 is configured to output a notification signal under the control of the control unit 30 when, for example, a detectable gas 1 having a predetermined concentration or higher is detected. The notification unit 33 includes one or more devices, such as a speaker that outputs an audio signal and a lamp that outputs an optical signal. The display unit 34 includes a display device such as an LCD monitor. The operation unit 35 includes one or more input devices, such as mechanical buttons or a touch panel.

[0046] The control unit 30 accepts input operations such as instructions to start a detection operation via the operation unit 35. The control unit 30 causes the display unit 34 to display the detection results. The detection results include concentration information of the detectable gas 1. For example, if the detected gas concentration value can be displayed within the LEL range (0% LEL to 100% LEL), the control unit 30 displays the concentration information as an LEL concentration value, and if the concentration value is high and exceeds the LEL range, the control unit 30 displays the concentration information as a VOL concentration value. The detection results may further include information indicating the gas species of the detectable gas 1. The control unit 30 also causes the display unit 34 to display various information such as the status of the gas detector 100 (remaining battery charge, presence or absence of an error, etc.).

[0047] (Connection structure between the control unit and the first gas detection unit) In the first embodiment, the control unit 30 in the housing 20 is electrically connected to the first gas detection unit 11 and the pump 15 in the gas introduction unit 10 via the elongated portion 12.

[0048] Specifically, as shown in Fig. 4, the flexible tube 14 includes a flow path 41 through which the detectable gas 1 flows, and an electric wire 42 that electrically connects the first gas detection unit 11 and the control unit 30 (see Fig. 3). The flexible tube 14 has a tubular circumferential wall 43 that forms the outer surface of the flexible tube 14, and the flow path 41 is formed by an internal space surrounded by the circumferential wall 43. The circumferential wall 43 and the covered portion of the electric wire 42 are integrated together. As a result, the flow path 41 and the electric wire 42 are provided integrally with the flexible tube 14. Note that in Fig. 1, the shape of the flexible tube 14 is simplified and shown as a tube with a circular cross section.

[0049] As a result, the flow path 41 connects the gas inlet 21 of the housing 20 and the internal space of the probe 13 so as to fluidly communicate with each other, as shown in Fig. 2. The electric wire 42 is electrically connected to the control unit 30 of the housing 20 via the terminal 26 provided on the connector 23, and is also electrically connected to the first gas detection unit 11 and the pump 15 via the terminal 13g provided on the probe 13 (accommodating unit 13b), as shown in Fig. 3. The electric wire 42 is composed of one or more conductor wires. The electric wire 42 may include multiple electric wires such as an electric wire for transmitting an electric signal and an electric wire for transmitting power.

[0050] The control unit 30 is configured to supply power from the power supply unit 32 to the first gas detection unit 11 and the pump 15 via an electric wire 42, thereby driving the first gas detection unit 11 and the pump 15. The control unit 30 is configured to control the operation of the first gas detection unit 11 and the pump 15 via the electric wire 42. The control unit 30 is configured to acquire the output of the first gas detection unit 11 via the electric wire 42. The control unit 30 is configured to acquire the concentration of the detectable gas 1 introduced into the probe 13 based on the output of the first gas detection unit 11.

[0051] (Protection control of the second gas detector) The control unit 30 is configured to perform control to protect the second gas detection unit 25 in accordance with the detection result of the first gas detection unit 11. Specifically, the control unit 30 is configured to protect the second gas detection unit 25 by switching the second gas detection unit 25 between an activated state and an inactivated state.

[0052] Activating the gas detection unit means heating the gas detection unit (gas detection element) to a predetermined operating temperature by passing electricity through the gas detection unit, while deactivating the gas detection unit means lowering the temperature of the gas detection unit (gas detection element) below the operating temperature by not passing electricity through the gas detection unit.

[0053] 2, the control unit 30 activates the first gas detection unit 11 and the second gas detection unit 25 at a predetermined detection timing while the pump 15 is causing the detectable gas 1 to flow toward the exhaust port 22. As a result, the control unit 30 acquires the output of the first gas detection unit 11, which the detectable gas 1 reaches first. The control unit 30 compares the acquired output of the first gas detection unit 11 with a threshold value for determining whether to perform protection control for the second gas detection unit 25. If the output of the first gas detection unit 11 exceeds a preset threshold value, the control unit 30 stops powering the second gas detection unit 25 and switches the second gas detection unit 25 to an inactivated state.

[0054] As a result, when the detectable gas 1 that has passed through the first gas detection unit 11 and the long section 12 reaches the second gas detection unit 25, the second gas detection unit 25 is in an inactivated state. Since the second gas detection unit 25 is exposed to the detectable gas 1 while remaining in an inactivated state, the second gas detection unit 25 is protected from deterioration due to high-concentration gas. In the inactivated state, the second gas detection unit 25 does not detect the detectable gas 1.

[0055] The flow of protection control over time will be described with reference to Figure 5. After the introduction of detectable gas 1 begins (pump 15 starts operating), at timing t1, the detectable gas 1 reaches first gas detection unit 11. Then, at timing t2, control unit 30 acquires the detection result of first gas detection unit 11. Then, after detectable gas 1 passes through elongated section 12, at timing t3, the detectable gas 1 reaches second gas detection unit 25. If control unit 30 detects a high concentration gas based on the detection result at timing t2, it switches second gas detection unit 25 to an inactivated state by timing t3.

[0056] In this way, the long portion 12 increases the time length from time t1 to time t3 (delays time t3) so that the second gas detection unit 25 can be switched to an inactivated state at a point in time before time t3. In the first embodiment, the long portion 12 has a predetermined length so that the time required for the detectable gas 1 to pass through the first gas detection unit 11 to reach the second gas detection unit 25 (the time length from t1 to t3) is longer than the time required to perform protection control of the second gas detection unit 25.

[0057] In other words, the length of the long section 12 is set so that the total distance of the path length from the first gas detection section 11 to the long section 12, the length of the long section 12, and the path length from the gas inlet 21 to the second gas detection section 25 is greater than the travel distance of the detectable gas 1, which is calculated from the flow rate (set value) of the detectable gas 1 controlled by the pump 15 and the time (design value) required from when the detectable gas 1 reaches the first gas detection section 11 until control is performed to switch the second gas detection section 25 to an inactivated state. In addition, the length of the long section 12 is determined taking into consideration the relationship (balance) between the inner diameter of the long section 12 (inner diameter of the flow path 41) and the suction flow rate of the pump 15.

[0058] For example, the length of the elongated portion 12 is longer than the path length of the gas flow path 24 from the gas inlet 21 to the second gas detection unit 25. For example, the length of the elongated portion 12 is longer than the path length of the gas flow path 24 inside the housing 20 (the path length from the gas inlet 21 to the exhaust port 22).

[0059] In the first embodiment, the gas flow path 24 in the housing 20 does not have a long portion, and the long portion 12 of the gas introduction section 10 adjusts the time it takes for the gas to reach the second gas detection section 25 (the length of time from timing t1 to timing t3).

[0060] (Gas detector operation) Next, the operational control of the gas detector 100 of the first embodiment will be described with reference to Fig. 6. The following control is executed by the control unit 30. In the following description, Figs. 1 to 3 will be referred to for the configuration of each part of the gas detector 100.

[0061] In step S1, the control unit 30 starts driving the pump 15. The control unit 30 executes the driving start process by, for example, accepting an operation input to the operation unit 35 to start a detection operation.

[0062] In step S2, the control unit 30 controls the gas detection units (first gas detection unit 11, second gas detection unit 25) to be energized and to activate the gas detection units.

[0063] In step S3, the control unit 30 determines whether or not a high concentration gas has been detected by the first gas detection unit 11. That is, the control unit 30 determines whether or not the output of the first gas detection unit 11 has exceeded a threshold value.

[0064] If it is determined in step S3 that the output of the first gas detection unit 11 exceeds the threshold value, the control unit 30 performs control to deactivate the second gas detection unit 25 in step S4. That is, the control unit 30 stops power supply to the second gas detection unit 25. This protects the second gas detection unit 25 from high-concentration gas.

[0065] On the other hand, if it is determined in step S3 that the output of the first gas detection unit 11 does not exceed the threshold value, the control unit 30 performs control to continue activating (energizing) the second gas detection unit 25 in step S5.

[0066] In step S6, the control unit 30 processes data of the detection results based on the outputs from the first gas detection unit 11 and the second gas detection unit 25. The control unit 30 calculates a gas concentration value (VOL concentration value) based on the output of the first gas detection unit 11. The control unit 30 calculates a gas concentration value (LEL concentration value) based on the output of the second gas detection unit 25. Note that if the control unit 30 performs control to protect the second gas detection unit 25 in step S4 (i.e., if a high concentration gas is detected), the detection result based on the output of the second gas detection unit 25 is not acquired.

[0067] In step S7, the control unit 30 controls the display unit 34 to output (display) the acquired detection result. If the detection result is a low concentration within the measurable range of the second gas detection unit 25, the LEL concentration value is displayed on the display unit 34. If the detection result is outside the measurable range of the second gas detection unit 25, the VOL concentration value is displayed on the display unit 34. Furthermore, if the gas concentration value is a high concentration equal to or greater than a preset notification threshold, the control unit 30 outputs a notification signal (such as a notification sound) from the notification unit 33. This completes the detection operation of the gas detector 100.

[0068] (Effects of the first embodiment) In the first embodiment, the following effects can be obtained.

[0069] In the first embodiment, as described above, in the configuration in which protection of the second gas detection unit 25 is controlled in accordance with the detection result of the first gas detection unit 11, the first gas detection unit 11 and the elongated portion 12 are provided in the gas inlet 10 outside the housing 20, eliminating the need to accommodate the first gas detection unit 11 and the elongated portion 12 within the housing 20. Therefore, even when the elongated portion 12 is provided with a sufficient length to ensure the time between when a high concentration of the detectable gas 1 is detected by the first gas detection unit 11 and when it reaches the second gas detection unit 25, the housing 20 can be prevented from becoming large. Furthermore, since it is not necessary to accommodate the first gas detection unit 11 and the elongated portion 12 in the housing 20, the housing structure can be simplified. As a result, even when the upstream first gas detection unit 11 and the elongated portion 12 are provided with a function to protect the downstream second gas detection unit 25, the housing 20 can be prevented from becoming large and the housing structure from becoming complex. Furthermore, the long section 12, which is used to collect the atmosphere containing the target gas present at a location distant from the housing 20, also serves the function of protecting the second gas detection section 25, thereby preventing the gas detector from becoming large and the housing structure from becoming complex.

[0070] Furthermore, in the first embodiment, as described above, the long section 12 includes the flow path 41 for circulating the detectable gas 1 and the electric wire 42 for electrically connecting the first gas detection section 11 and the control section 30. This eliminates the need to separately connect the flow path 41 and the electric wire 42 between the gas inlet section 10 in which the first gas detection section 11 is provided and the housing 20 in which the control section 30 is housed, and the flow path 41 and the electric wire 42 can be integrated into the long section 12, thereby simplifying the device configuration.

[0071] In the first embodiment, as described above, the first gas detection unit 11 has an optical gas detection element or a gas thermal conduction gas detection element. These gas detection elements have high resistance to high-concentration gases because gas detection does not involve chemical or catalytic reactions. Therefore, the first gas detection unit 11 can be provided with a gas detection element that is highly resistant to high-concentration gases (i.e., that is less likely to deteriorate even when exposed to high-concentration gases).

[0072] Furthermore, in the first embodiment, as described above, the gas introduction unit 10 includes the probe 13 provided at the tip of the gas introduction unit 10 and having the first gas detection unit 11, and the long portion 12 includes the flexible tube 14 connecting the gas inlet 21 of the housing 20 to the probe 13. This allows an extension attachment including the probe 13 and the flexible tube 14 for sampling air containing the target gas present at a location away from the housing 20 to be provided with the function of the gas introduction unit 10. In other words, by providing the first gas detection unit 11 to the probe 13, the probe 13 can be configured not just as a gas introduction tube but also as a housing for housing the first gas detection unit 11. The flexible tube 14 for extending the movement range of the probe 13 can be configured as the long portion 12 for generating a delay in the arrival of the gas at the second gas detection unit 25. This effectively prevents the overall size of the gas detector 100 from increasing, compared to when the housing and long portion 12 for the first gas detection unit 11 are provided separately from the extension attachment including the probe 13 and the flexible tube 14.

[0073] Furthermore, in the first embodiment, as described above, the first gas detection section 11 and the second gas detection section 25 have different sensitivity characteristics to the detectable gas 1, and the second gas detection section 25 has a gas detection element that is less resistant to high-concentration gases than the first gas detection section 11. As a result, by performing protection control of the second gas detection section 25 in accordance with the detection result of the first gas detection section 11 until the gas whose arrival has been delayed by the elongated section 12 reaches the second gas detection section 25, it is possible to protect the gas detection element that is less resistant to high-concentration gases than the first gas detection section 11 from deterioration due to high-concentration gases.

[0074] [Second embodiment] Next, the configuration of a gas detector 200 according to a second embodiment will be described with reference to Figures 7 to 9. In the second embodiment, unlike the first embodiment in which power is supplied to the first gas detection unit 11 from the power supply unit 32 in the housing 20, a power supply unit 131 is provided in the probe 113 of the gas introduction unit 110, so that the probe 113 can detect gas independently. In the second embodiment, the same components as those in the first embodiment will be designated by the same reference numerals, and their description will be omitted.

[0075] As shown in FIG. 7, in a gas detector 200 of the second embodiment, a gas inlet 110 includes a probe 113 configured to be capable of detecting gas independently.

[0076] That is, the probe 113 further includes a probe control unit 130, a power supply unit 131, an operation unit 132, and a notification unit 133 in addition to the first gas detection unit 11 and the pump 15.

[0077] The probe control unit 130 includes a processor such as a CPU. The probe control unit 130 controls the first gas detection unit 11, the pump 15, and the notification unit 133. The probe control unit 130 is communicably connected to the control unit 30 of the housing 20 via the elongated unit 12 (electric wire 42).

[0078] The power supply unit 131 supplies power to each part of the probe 113 (the first gas detection unit 11, the pump 15, the probe control unit 130, and the alarm unit 133). The power supply unit 131 is composed of a battery and a power supply circuit. In the second embodiment, for example, the power supply unit 32 of the housing 20 may be provided with a connection part to a commercial power source (external power source), and a secondary battery attached to the power supply unit 131 may be charged by power supplied from the commercial power source via the long part 12 (electric wire 42).

[0079] The operation unit 132 includes a switch that accepts an input operation. When the probe 113 operates independently, the probe control unit 130 switches between starting and stopping control of gas detection in response to an operation input to the operation unit 132. The notification unit 133 includes, for example, a speaker.

[0080] 8, the gas detector 200 of the second embodiment can operate in a first detection mode (see FIG. 8(A)) in which the probe 113 is connected to the housing 20 via the elongated portion 12 and gas detection is performed by both the first gas detection unit 11 and the second gas detection unit 25. The gas detection operation in the first detection mode is substantially the same as the gas detection operation by the gas detector 100 of the first embodiment described above.

[0081] In the first detection mode, the first gas detection unit 11 and the pump 15 are controlled by a control signal from the control unit 30 via the electric wire 42. As a result, the detection operation in the first detection mode is performed under the control of the control unit 30. The protection control of the second gas detection unit 25 in the first detection mode is the same as in the first embodiment, and therefore a description thereof will be omitted. In the first detection mode, the probe control unit 130 does not control the detection operation, and therefore the probe control unit 130 is indicated by a dashed line in FIG. 8(A).

[0082] The gas detector 200 of the second embodiment can operate in a second detection mode (see Figure 8(B)) in which gas detection is performed only by the first gas detection unit 11 when the connection between the probe 113 and the long portion 12 is released.

[0083] In the second detection mode, the probe control unit 130 controls the first gas detection unit 11 and the pump 15 in response to an operation input to the operation unit 132 (see FIG. 7). The suction force (negative pressure) of the pump 15 introduces the detectable gas 1 into the probe 113 from the tip of the pipe 13a. After passing through the first gas detection unit 11 and the pump 15 in the flow path 13d, the detectable gas 1 is discharged from the other end of the probe 113 (the connection port 13f of the storage unit 13b). The probe control unit 130 detects the detectable gas 1 by energizing the first gas detection unit 11 at the gas detection timing. If a detectable gas 1 having a predetermined concentration or higher is detected during operation in the first detection mode, the probe control unit 130 controls the alarm unit 133 to issue an alarm. During operation in the second detection mode, gas detection is not performed in the housing 20. Therefore, the control unit 30 is indicated by a dashed line in FIG. 8(B).

[0084] 9, a user can use the probe 113 as a handheld, simple gas detector by separating the probe 113 from the elongated portion 12 and the housing 20 and holding and carrying the probe 113 by the grip portion 13c of the housing portion 13b. For example, before a gas leak test, the user can use the second detection mode to perform preliminary detection to determine the positions and number of test points. In this case, the detection work can be performed with a simple and minimal configuration using only the probe 113, without the range of movement of the probe 113 being limited by the elongated portion 12 or the housing 20.

[0085] (Effects of the second embodiment) In the second embodiment, similar to the first embodiment, in a configuration in which protection of the second gas detection unit 25 is controlled in accordance with the detection result of the first gas detection unit 11, the first gas detection unit 11 and the elongated portion 12 are provided in the gas inlet portion 110 outside the housing 20, thereby preventing the housing 20 from becoming large. Furthermore, since it is not necessary to house the first gas detection unit 11 and the elongated portion 12 in the housing 20, the housing structure can be simplified. As a result, even when the upstream first gas detection unit 11 and the elongated portion 12 are provided with the function of protecting the downstream second gas detection unit 25, the housing 20 can be prevented from becoming large and the housing structure can be prevented from becoming complex. Furthermore, since the elongated portion 12, which is used to collect air containing the target gas present at a position away from the housing 20, also serves the function of protecting the second gas detection unit 25, the gas detector can be prevented from becoming large and the housing structure can be prevented from becoming complex.

[0086] Furthermore, in the second embodiment, as described above, the probe 113 further includes the pump 15 for circulating the detectable gas 1 and the power supply unit 131, and is configured to be able to perform gas detection separately from the flexible tube 14 and the housing 20. As a result, by utilizing the fact that the probe 113 has the first gas detection unit 11, the probe 113 can be separated from the flexible tube 14 and the housing 20 and function as a simple gas detector by itself. This makes it possible to selectively use a usage mode (second detection mode) in which gas detection is performed by the probe 113 alone (only the first gas detection unit 11), and a usage mode (first detection mode) in which the probe 113 is connected to the flexible tube 14 and gas detection is performed by both the first gas detection unit 11 and the second gas detection unit 25.

[0087] [Variations] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims rather than the above description of the embodiments, and further includes all modifications (variations) within the meaning and scope of the claims.

[0088] For example, in the first and second embodiments described above, the elongated portion 12 includes the flow path 41 for circulating the detectable gas 1 and the electric wire 42 for electrically connecting the first gas detection portion 11 and the control portion 30. However, the present invention is not limited to this. In the present invention, the elongated portion 12 does not necessarily need to be provided with the electric wire 42. In other words, the electric wire 42 for electrically connecting the first gas detection portion 11 and the control portion 30 may be provided separately from the elongated portion 12.

[0089] In the first and second embodiments, the first gas detection unit 11 includes an optical gas detection element or a gas thermal conduction gas detection element, but the present invention is not limited to this. In the present invention, the first gas detection unit 11 may include a gas detection element other than an optical gas detection element or a gas thermal conduction gas detection element.

[0090] In the first and second embodiments, the gas introduction section 10 (110) includes the probe 13 (113) having the first gas detection section 11, and the long section 12 includes the flexible tube 14. However, the present invention is not limited to this. The gas introduction section 10 of the present invention does not have to include the probe 13. The long section 12 may be composed of a material other than the flexible tube 14, or the long section 12 may be composed of the flexible tube 14 and a material other than the flexible tube 14. The gas introduction section 10 has one end for introducing the detectable gas and the other end for discharging the detectable gas, and may have any structure as long as it includes the first gas detection section and the long section. The gas introduction section 10 may structurally include a hollow section that allows gas to flow between one end and the other end, and the first gas detection section can detect the detectable gas as the gas flows through the hollow section, and the long section may be located closer to the other end than the first gas detection section.

[0091] In the second embodiment (FIG. 9), the probe 113 is configured as a gas introduction member including the pipe 13a and the cylindrical housing portion 13b. However, the present invention is not limited to this. As shown in FIG. 10, the probe 113 may be a handheld gas detector (second gas detector) that can be used in combination with a housing 20 (first gas detector). The probe 113 accommodates the first gas detection unit 11, the pump 15, the power supply unit 131, and the like in a rectangular parallelepiped housing portion 13b that can be held by an operator. The pipe 13a is connected to the tip of the housing portion 13b, and a connection port 13f for connecting to the elongated portion 12 is formed on the side of the housing portion 13b. In the first detection mode, the probe 113 is connected to the housing 20 by the elongated portion 12. In the second detection mode, the probe 113 is disconnected from the elongated portion 12, and the probe 113 performs gas detection independently. The connection port 13f functions as an exhaust port in the second detection mode. For convenience, the probe control unit 130 and the notification unit 133 are omitted from FIG.

[0092] Although the first and second embodiments have been described above with reference to examples in which the first gas detection unit 11 is provided inside the probe 13 (113), the present invention is not limited thereto. In the present invention, the first gas detection unit 11 may be provided somewhere other than the probe 13. For example, in addition to the probe 13 and the flexible tube 14, the gas inlet 10 may be provided with a connecting member that connects the probe 13 and the flexible tube 14, and the first gas detection unit 11 may be provided on the connecting member. The first gas detection unit 11 may be provided on one end (tip) of the gas inlet 10 relative to the elongated portion 12. Furthermore, when the probe 13 is composed of a pipe 13a and a housing 13b, the first gas detection unit 11 may be provided on the pipe 13a. The probe 13 does not necessarily have to be composed of the pipe 13a and the housing 13b.

[0093] In the first and second embodiments, the pump 15 is provided in the gas introduction part 10 (probe 13), but the present invention is not limited to this. In the present invention, the pump 15 may be provided in the gas flow path 24 inside the housing 20. Furthermore, the gas introduction part 10 (probe 13) and the gas flow path 24 inside the housing 20 may each be provided with a pump (i.e., a first pump and a second pump).

[0094] In the first and second embodiments (see FIG. 6), the second gas detection unit 25 is protected by activating the second gas detection unit 25 (step S2) and deactivating the second gas detection unit 25 when a high-concentration gas is detected (step S4). However, the present invention is not limited to this. In the present invention, the second gas detection unit 25 may be deactivated, and when a high-concentration gas is detected by the first gas detection unit 11, the second gas detection unit 25 may remain deactivated, and only when a low-concentration gas is detected, the second gas detection unit 25 may be activated.

[0095] Although the first and second embodiments (see FIG. 6 ) illustrate examples in which the second gas detection unit 25 is protected by inactivating the second gas detection unit 25, the present invention is not limited thereto. For example, a dilution unit for diluting sampled air introduced from the gas inlet 10 may be provided upstream of the second gas detection unit 25 in the gas flow path 24 of the housing 20. When a high concentration of the detectable gas 1 in the sampled air is detected by the first gas detection unit 11, the control unit 30 controls the dilution unit to dilute the sampled air with a dilution gas. The dilution gas is a gas whose concentration of the detectable gas 1 is lower than a threshold value for determining whether or not to perform protection control. The dilution gas may be air near the housing 20 away from the sampling location, or may be gas supplied from a gas cylinder or the like. The dilution reduces the concentration of the detectable gas 1 when it reaches the second gas detection unit 25, thereby preventing the second gas detection unit 25 from being exposed to a high concentration gas. In this case, the control unit 30 and the dilution unit are examples of the "control means" in the claims.

[0096] Alternatively, the gas flow path 24 may be provided with a first path that passes through the second gas detection unit 25 and connects to the exhaust port 22, and a second path that does not pass through the second gas detection unit 25 and connects to the exhaust port 22, in parallel, and a flow path switching valve that switches the connection of the gas inlet between the first path and the second path may be provided. When the first gas detection unit 11 detects a high concentration of the detectable gas 1 in the sampled air, the control unit 30 controls the flow path switching valve to switch the connection of the gas inlet 21 to the second path. This allows the high concentration of the detectable gas 1 to be discharged without reaching the second gas detection unit 25, thereby preventing the second gas detection unit 25 from being exposed to the high concentration gas. In this case, the control unit 30 and the flow path switching valve are an example of the "control means" in the claims.

[0097] In the first and second embodiments, examples have been shown in which two gas detection units, the first gas detection unit 11 and the second gas detection unit 25, are provided, but the present invention is not limited to this. In the present invention, three or more gas detection units may be provided. In this case, depending on the detection units provided, control may be performed to protect one gas detection unit (second gas detection unit), or control may be performed to protect two or more gas detection units (second gas detection units).

[0098] Furthermore, while the first and second embodiments described above illustrate examples in which the concentration value of the detectable gas 1 is detected, the present invention is not limited to this. In addition to detecting the concentration value of the detectable gas 1, the present invention may also identify the gas species contained in the detectable gas 1. For example, the gas species of the detectable gas 1 contained in the sampled air may be identified based on the detection results of multiple gas detectors with different sensitivity characteristics to gas species. Furthermore, the gas species and concentration value of the detectable gas 1 contained in the sampled air may be identified by separating the gas contained in the sampled air into components using the principles of gas chromatography and separately detecting the separated component gases.

[0099] Although the first and second embodiments have been described above in which the first gas detection unit 11 and the second gas detection unit 25 detect the same type of detectable gas 1, the present invention is not limited to this. In the present invention, the first gas detection unit 11 and the second gas detection unit 25 may detect different gas species. For example, the first gas detection unit 11 may be a gas detection unit dedicated to protection control that detects a specific gas species that accelerates deterioration of the second gas detection unit 25 as the first detectable gas, while the second gas detection unit 25 may detect a gas species other than the first detectable gas as the second detectable gas. In this case, the gas detector detects the second detectable gas, but the control unit 30 may perform control to protect the second gas detection unit 25 when it detects the presence of the first detectable gas in the sampled air.

[0100] In the first and second embodiments, the detectable gas 1 is a fuel gas, but the present invention is not limited to this. The type of detectable gas is not particularly limited in the present invention. The present invention is applicable to cases where deterioration of the second gas detection unit 25 is accelerated due to a high concentration of the detectable gas.

[0101] In the first embodiment, the control unit 30 is provided inside the housing 20, but the present invention is not limited to this. In the present invention, the control unit 30 may be provided in the probe 13 (accommodation unit 13b).

[0102] In the first and second embodiments, the pipe 13a is made of a hard material such as metal, but the present invention is not limited to this. In the present invention, the pipe 13a may be made of a flexible tube or a soft material, or a combination of these. Furthermore, the pipe 13a may have a structure whose length can be changed (for example, a bellows structure or a multi-tube structure in which the inner tube can be pulled out).

[0103] In the second embodiment, the power supply unit 32 is provided in the housing 20, and the power supply unit 131 is provided in the probe 113. However, the present invention is not limited to this. In the present invention, the power supply unit 32 may not be provided in the housing 20, and each unit in the housing 20 may be driven only by the power supply unit 131.

[0104] In the first and second embodiments, the gas detector 100 (200) is a portable, simple stationary gas detector, but the present invention is not limited to this. In the present invention, the gas detector 100 (200) may be a handheld gas detector. [Explanation of symbols]

[0105] 1. Gas to be detected 10, 110 Gas inlet 11 First gas detection unit 12 Long section 13, 113 probe 14 Flexible tubing 15 Pump 20 Case 21 Gas inlet 22 Exhaust port 24 Gas flow path 25 Second gas detection unit 30 Control unit (control means) 41 Flow path 42 Electric wire 100, 200 Gas Detector 131 Power supply section

Claims

1. a gas inlet having one end for introducing a gas to be detected and another end for discharging the gas to be detected; a housing having a gas inlet and an exhaust port to which the other end of the gas introduction section is connected; a control means for controlling the detection operation of the detection target gas, The gas introduction section a first gas detection unit that detects the target gas introduced into the gas introduction unit; a long portion that is disposed closer to the other end than the first gas detection portion and that causes a delay in arrival of the detection target gas sent from the first gas detection portion to the gas inlet, The housing includes: a gas flow path connecting the gas inlet and the exhaust port; a second gas detection unit disposed in the gas flow path and configured to detect the detection target gas; the control means is configured to perform control to protect the second gas detection unit in accordance with a detection result of the first gas detection unit, The control means is housed in the housing, The long portion includes a flow path for circulating the gas to be detected, and an electric wire for electrically connecting the first gas detection portion and the control means.

2. 2. The gas detector according to claim 1, wherein the first gas detection section has an optical gas detection element or a gas thermal conduction gas detection element.

3. the gas inlet includes a probe provided at a tip of the gas inlet and having the first gas detector; 3. The gas detector according to claim 1, wherein the elongated portion includes a flexible tube connecting the gas inlet of the housing and the probe.

4. a gas inlet having one end for introducing a gas to be detected and another end for discharging the gas to be detected; a housing having a gas inlet and an exhaust port to which the other end of the gas introduction section is connected; a control means for controlling the detection operation of the detection target gas, The gas introduction section a first gas detection unit that detects the target gas introduced into the gas introduction unit; a long portion that is disposed closer to the other end than the first gas detection portion and that causes a delay in arrival of the detection target gas sent from the first gas detection portion to the gas inlet, The housing includes: a gas flow path connecting the gas inlet and the exhaust port; a second gas detection unit disposed in the gas flow path and configured to detect the detection target gas; the control means is configured to perform control to protect the second gas detection unit in accordance with a detection result of the first gas detection unit, the gas inlet includes a probe provided at a tip of the gas inlet and having the first gas detector; the elongated portion includes a flexible tube connecting the gas inlet of the housing and the probe; The probe is The apparatus further includes a pump and a power supply unit for circulating the gas to be detected, A gas detector configured to be capable of performing gas detection separately from the flexible tube and the housing.

5. 5. The gas detector according to claim 1, wherein the first gas detection unit and the second gas detection unit have different sensitivity characteristics to the detected gas, and the second gas detection unit has a gas detection element that has lower resistance to high-concentration gases than the first gas detection unit.

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