JP7292073B2 - LEAK TESTING SYSTEM AND LEAKAGE TESTING METHOD - Google Patents

Description

The present invention relates to a leak test system and a leak test method.

From the viewpoint of security, gas appliances such as gas water heaters must be strictly managed to ensure that there are no defects such as gas leaks at the time of shipment. As a method to confirm that there are no gas leaks in gas appliances, for example, there is a method of sealing gas such as air in the gas pipe inside the gas appliance, submerging it in a liquid tank, and confirming that there are no bubbles. A method is known in which a liquid for leak inspection (foaming liquid) is sprinkled on a location where it is likely to occur to confirm that there is no foaming.

In addition, Patent Document 1 is an invention of a gas combustion apparatus and an airtight leak inspection method thereof that facilitates piping connection work and facilitates airtightness leak inspection at the time of manufacturing and shipping without changing the existing piping configuration. disclose. The invention includes an equipment main body provided with one or more burners, first and second connecting portions to which an external gas supply pipe can be connected, supply of fuel gas to the burner side, cutoff of the supply, or control of the amount of supply. a regulating control valve, a conduit provided with a second connection interposed between the first connection and the control valve to permit selective closure of the first and second connections; Airtight leak inspection means (leak tester and compression pump) are connected to the first or second connection part to pressurize the pipeline, making it possible to inspect airtight leaks, and existing piping equipment can be used. It is said that simplification of airtight leak inspection at the time of shipment can be realized.

JP-A-2000-291943

By the above-described leak test method, it is possible to reliably confirm that there is no leak. However, the method of submerging the entire gas appliance in a liquid tank has the problem that the equipment for inspection becomes large, and operations such as submersion in the liquid tank, lifting, and drying are required, and there is a problem that inspection throughput cannot be increased. be. In addition, the method of spraying the test liquid on areas where there is a possibility of leakage has the problem that if there is a leak in the area where it did not fall, it cannot be detected. may be required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a leak test system and a leak test method that can perform leak tests on gas appliances reliably and with high throughput.

In order to solve the above problems, in a first aspect of the present invention, detection light is emitted to an inspection object, reflected light from the inspection object is received, and a signal corresponding to the intensity of the received light is generated. a gas detector for outputting and calculating the concentration of the gas to be detected based on the signal; a direction control mechanism for controlling the direction of the detected light; and a leakage determination unit that acquires the concentration of the gas and determines whether the concentration is equal to or higher than a predetermined value. It may further include a reporting unit that reports the determination result of the leakage determination unit.

Note that the concentration of the gas to be detected may be the column density. The column density is the density of the gas calculated from the degree of light absorption by the gas when the gas that absorbs the detection light exists on the optical path of the detection light, and depends on the length of the optical path. By dividing the column density by the length of the optical path, the average concentration of the gas on the optical path can be calculated. Therefore, column density can be used instead of gas concentration as long as the optical path length is constant. Hereinafter, in this specification, the concept of "density" includes the concept of "column density" as long as the optical path length satisfies a certain condition.

In the leakage inspection system described above, the direction control mechanism may control the direction so that the detection light is scanned over the entire area of the inspection object. Alternatively, the direction control mechanism may control the direction so that the detection light is scanned along a predetermined route of the inspection object. Alternatively, the direction control mechanism may control the direction so that a single predetermined region of the inspection object is irradiated with the detection light. Alternatively, the direction control mechanism may control the direction so that a plurality of predetermined regions of the inspection object are sequentially irradiated with the detection light. Further, a type determining means for reading an identification code placed near the inspection object and determining the type of the inspection object from the read identification code, or acquiring an image of the inspection object and acquiring the acquired image and a type determination means for determining the type of the inspection object from the It may be controlled.

In the leakage inspection system described above, when the gas detector detects an estimated leakage concentration exceeding the background concentration, the direction control mechanism detects the detection in the vicinity of the irradiation position of the detection light at the time when the estimated leakage concentration is detected. The directional displacement speed of light may be controlled to be slower than the normal directional displacement speed. When the gas detector detects the estimated leakage concentration exceeding the background concentration, the gas detector may detect the gas to be detected with a measurement integration time longer than a normal measurement integration time.

In a second aspect of the present invention, there is provided a leak inspection method using the leak inspection system described above, comprising the steps of: introducing an inspection gas containing the gas to be detected into the inspection object; a step of irradiating the inspection object to which the gas has been introduced with the detection light while controlling the direction of the detection light to measure the concentration of the gas to be detected; and determining.

In the leak inspection method described above, prior to the step of introducing the inspection gas, a step of introducing a background measurement gas substantially free of the gas to be detected into the inspection object; irradiating the inspection object to which the gas has been introduced with the detection light to measure the background concentration of the gas to be detected, wherein the concentration measurement value of the gas to be detected is measured in the step of measuring the concentration. and the background concentration, and the difference may be corrected as the concentration of the detected gas. In this case, in the step of measuring the concentration, if the measured concentration value of the gas to be detected is equal to or greater than a predetermined value exceeding the background concentration, the directional displacement speed of the detection light is reduced, or the gas detector may be used to lengthen the measurement integration time of .

In the leakage inspection method described above, the gas to be detected may be a combustible gas, and the concentration of the combustible gas contained in the inspection gas may be less than the lower explosion limit. For example, the gas to be detected may be methane, and the concentration of methane contained in the inspection gas may be less than 5 vol %. If it is determined in the determining step that the concentration is equal to or higher than a predetermined value, it may be notified that there is a gas leak. It should be noted that the above concept of "introduction" includes both concepts of "enclosing" and "while flowing".

1 is a configuration diagram showing an outline of a leakage inspection system 10; FIG. 2 is a block diagram showing an outline of gas detector 100, direction control mechanism 200 and control section 300. FIG. 4 is a conceptual diagram showing an example of direction control of detection light 120 in direction control mechanism 200. FIG. 4 is a conceptual diagram showing an example of direction control of detection light 120 in direction control mechanism 200. FIG. 4 is a conceptual diagram showing an example of direction control of detection light 120 in direction control mechanism 200. FIG. It is a flow figure showing an example of a leak test method. It is a flow figure showing an example of a leak test method. It is a flow figure showing an example of a leak test method.

(Embodiment)
FIG. 1 is a configuration diagram showing an outline of a leakage inspection system 10. As shown in FIG. A leak test system 10 of the present embodiment performs a leak test on an object 500 to be tested, and includes a gas detector 100 , a direction control mechanism 200 , a controller 300 and a gas supply system 400 . FIG. 2 is a block diagram showing an outline of the gas detector 100, direction control mechanism 200 and control section 300. As shown in FIG.

Inspection object 500 is an inspection object in leak inspection system 10, and is, for example, a gas appliance such as a gas water heater. The leakage inspection system 10 can be used for pre-shipment inspections for confirming that there is no gas leakage or the like in products such as gas appliances before they are shipped. In the following description, gas leak inspection will be mainly described, but the leak inspection system 10 can also be applied to liquid leak inspection in water pipes, airtightness inspection of radiators, exhaust mufflers, hot water storage tanks, and the like. .

The inspection object 500 has a heat exchange section 504 , a combustion section 506 , a controller section 508 and a gas connection port 510 inside a housing 502 . A gas appliance, which is an example of the object to be inspected 500, is normally covered entirely with a panel, but here, the front panel is removed in order to perform an internal leak inspection.

Combustion section 506 is a structure that safely burns combustible gas such as city gas and propane gas supplied from a gas pipe (not shown). to water conducted in a water conduit (not shown). The controller section 508 controls the combustion section 506 as well as the water and combustible gas guided to the water conduit and the gas conduit. The gas conduit is connected to a gas connection port 510 and is externally supplied with combustion gas via the gas connection port 510 . A water connection port connected to the water conduit is omitted from the drawing.

The gas detector 100 has a light source section 102 , a light receiving section 104 , a signal detection section 106 , a concentration calculation section 108 and a display section 110 . The gas detector 100 irradiates the inspection object 500 with detection light 120 emitted by the light source unit 102, receives the reflected light 122 from the inspection object 500 by the light receiving unit 104, and generates a signal corresponding to the intensity of the received light. is output by the signal detection unit 106, and the concentration calculation unit 108 calculates the concentration of the gas to be detected based on the signal.

The light source unit 102 emits detection light 120 . The light source unit 102 emits, for example, frequency-modulated laser light as the detection light 120 . By frequency-modulating the laser light, a second harmonic signal corresponding to the gas concentration is generated. The wavelength (frequency) of the detection light 120 is preferably a wavelength that is absorbed by the gas to be detected but not absorbed by the background gas. When the gas to be detected is methane, infrared laser light with an oscillation wavelength of 1.65 μm band can be used as the detection light 120 . When the gas to be detected is hydrogen sulfide, infrared laser light with an oscillation wavelength in the 1.57 μm band can be used as the detection light 120 . When a semiconductor laser oscillator is used for the light source unit 102, a standard cell filled with the gas to be detected is prepared, and the light absorption in the standard cell is referred to so that the oscillation wavelength of the detection light 120 is equal to the absorption of the gas to be detected. It is preferable to adjust the operating temperature and the like of the semiconductor laser oscillator so that the center of the line is aligned.

The light receiving unit 104 receives the reflected light 122 from the inspection object 500 and outputs a signal corresponding to the intensity of the received light. Examples of the light receiving unit 104 include photoelectric conversion elements such as photodiodes and photomultipliers and their drive detection circuits. The light receiving unit 104 may include, for example, an optical filter such as a bandpass filter, a slit, a spectroscopic mechanism, and the like.

The signal detection unit 106 receives the received light signal output from the light receiving unit 104, and from the received light signal, a fundamental wave signal having a frequency equal to the modulation frequency of the detected light 120 and a double wave signal having a frequency equal to twice the modulation frequency. to detect Synchronous detection can be used to detect the fundamental wave signal and the double wave signal.

The concentration calculator 108 calculates the concentration of the gas to be detected based on the signal output from the light receiver 104 , and the display unit 110 displays the concentration of the gas to be detected calculated by the concentration calculator 108 . Further, the concentration calculator 108 has output means for outputting the calculated concentration value by wire or wirelessly. The measured density value is transmitted to the control section 300 via the output means.

A direction control mechanism 200 controls the direction of the detected light 120 . The orientation control mechanism 200 has a base stage 202 , a vertical orientation control stage 204 , a horizontal orientation control stage 206 and an orientation control section 208 . Gas detector 100 is fixed to horizontal control stage 206 . The vertical direction control stage 204 is slid in the direction of the arrow a1 relative to the base stage 202 in an arc, swings the gas detector 100 in the direction of the arrow a2, and aligns the irradiation point of the detection light 120 on the inspection object 500. It is vertically displaced as indicated by arrow a3. The horizontal direction control stage 206 is rotated and slid in the direction of the arrow b1 with respect to the vertical direction control stage 204, swings the gas detector 100 in the direction of the arrow b2, and irradiates the inspection object 500 with the detection light 120. The point is displaced horizontally as indicated by arrow b3. Orientation control 208 controls the movement of vertical control stage 204 and horizontal control stage 206 .

The control unit 300 has a leakage determination unit 302 and a notification unit 304 . Leak determination unit 302 acquires the concentration of the gas to be detected from gas detector 100 in conjunction with direction control mechanism 200, and determines whether the concentration is equal to or greater than a predetermined value. Interlocking with the direction control mechanism 200 is to transmit a direction control signal to the direction control unit 208 or receive a measurement timing signal from the direction control unit 208, and interlock with these direction control signals or timing signals to control the gas detector 100. The interlocking can be realized by obtaining the density value from the . The notification unit 304 notifies the determination result of the leakage determination unit 302 .

The gas supply system 400 supplies inspection gas and background measurement gas to the inspection object 500 via the gas connection port 510 . The gas supply system 400 includes an inspection gas cylinder 402 filled with an inspection gas, a stop valve 404 for the inspection gas cylinder 402, a background measurement gas cylinder 406 filled with a background measurement gas, and a stop for the background measurement gas cylinder 406. It has a valve 408 . The downstream sides of stop valves 404 and 408 are connected to gas connection port 510 . At the outlet of each gas cylinder, a regulator for pressure adjustment and a filter for removing mist may be installed, and each cylinder and valve are connected by a connector with a sealing performance that can withstand high gas pressure. Although connected, detailed description is omitted here.

The test gas contains the gas to be detected, and the background measurement gas does not substantially contain the gas to be detected. Here, "substantially free of the detectable gas" means not only containing no detectable gas at all, but also containing a very small amount of the detectable gas. This is the gist of it. The gas to be detected may be a combustible gas, and in this case, the concentration of the combustible gas contained in the test gas may be below the lower explosive limit. Methane can be exemplified as the gas to be detected, and in this case, the concentration of methane contained in the test gas can be less than 5 vol %.

The gas detector 100 described above irradiates the inspection object 500 with the detection light 120 and measures the concentration of the gas to be detected that is detected when there is leakage. If there is a leak, the concentration of the gas to be detected should be the highest at the leak location, so the location where the detection light 120 showing the highest concentration value can be estimated as the leak location. That is, according to the leak inspection system 10 of the present embodiment, it is possible to easily identify the leak location.

3 to 5 are conceptual diagrams showing an example of direction control of the detection light 120 in the direction control mechanism 200. FIG. 3 to 5, members such as the heat exchange section 504 inside the housing 502 of the inspection object 500 are indicated by broken lines.

The direction control mechanism 200 can control the direction so that the detection light 120 is scanned over the entire area of the inspection object 500, as shown in FIG. That is, by operating the direction control mechanism 200 to control the direction of the detection light 120 and scanning the detection light 120 along the line 512 shown in FIG. can be implemented. As a result, the leak test can be performed over the entire area of the test object 500 without omission.

The direction control mechanism 200 can also control the direction of the detection light 120 so that it is scanned along a predetermined route 514 of the inspection object 500, as shown in FIG. As described above, the direction control mechanism 200 is operated to control the direction of the detection light 120, and the detection light 120 is scanned along the route 514 shown in FIG. The inspection can be performed by narrowing down the area (route 514) requiring the leak inspection, passing the area where the leakage cannot occur or the possibility of the leakage substantially does not occur, and the efficiency of the inspection can be improved. can.

Further, the direction control mechanism 200 can control the direction so that the plurality of predetermined regions 516a to 516d of the inspection object 500 are sequentially irradiated with the detection light 120, as shown in FIG. As above, the direction control mechanism 200 can be operated to control the direction of the detected light 120 . As in the case of FIG. 4, the inspection can be performed by narrowing down the areas (predetermined areas 516a to 516d) requiring the leak inspection, and the efficiency of the inspection can be improved.

The direction control mechanism 200 can also control the direction so that the detection light 120 irradiates a single predetermined region of the inspection object 500 . Further, as shown in FIG. 5, an identification code 520 may be arranged near the inspection object 500. In this case, the identification code 520 is read, and the type of the inspection object 500 is determined from the read identification code 520. , the direction control mechanism 200 may control the direction so that the detection light 120 is irradiated to the irradiation region specific to the determined type. The determination of the type may be performed by acquiring an image of the inspection object 500 and determining the type of the inspection object 500 from the acquired image.

When the gas detector 100 detects the estimated leakage concentration exceeding the background concentration, the direction control mechanism 200 changes the directional displacement speed of the detection light 120 in the vicinity of the irradiation position of the detection light 120 at the time when the estimated leakage concentration is detected to the normal may be controlled to be slower than the directional displacement speed of . Alternatively, when the gas detector 100 detects an estimated leakage concentration exceeding the background concentration, the gas detector 100 may detect the gas to be detected with a measurement integration time longer than the normal measurement integration time. By measuring slower than the normal directional displacement speed or longer than the normal measurement integration time, that is, by performing detailed measurement, it becomes possible to detect a very small amount of leakage with high accuracy.

FIG. 6 is a flow diagram showing an example of a leak test method. First, the stop valve 408 of the gas supply system 400 is opened, the background measurement gas substantially free of the gas to be detected is introduced into the gas conduit inside the inspection object 500, and the stop valve 408 is closed. The background measurement gas is sealed (step 602). It is preferable that the gas in the gas conduit is exhausted before the background measurement gas is introduced, and the sealed background measurement gas is preferably pressurized to the atmospheric pressure or higher.

Next, the inspection object 500 into which the background measurement gas has been introduced is irradiated with the detection light 120, the background concentration of the gas to be detected is measured (step 604), and the background measurement gas is exhausted (step 606).

Next, the stop valve 404 of the gas supply system 400 is opened to introduce the inspection gas containing the gas to be detected into the gas conduit inside the inspection object 500, and the stop valve 404 is closed to release the inspection gas. Seal (step 608). In addition, it is preferable that the sealed inspection gas is in a pressurized state of atmospheric pressure or higher.

Next, the inspection object 500 into which the inspection gas has been introduced is irradiated with the detection light 120 while controlling the direction of the detection light 120, and the concentration of the gas to be detected is measured (step 610). The difference between the concentration measurement value of the detected gas and the background concentration measured in step 604 is calculated, and the difference is corrected as the concentration of the detected gas (step 612). After that, it is determined whether the measured (corrected) concentration is equal to or higher than a predetermined value (step 614), and if it is determined that the concentration is equal to or higher than the predetermined value, the presence of gas leakage is notified (step 616).

Leakage inspection can be performed as described above. According to the method shown in FIG. 6, since the concentration measurement value is corrected using the background concentration of the gas to be detected, it is possible to improve the measurement accuracy of the concentration of the gas to be detected and to perform an accurate leak inspection. In the method shown in FIG. 6, the measurement of the background density is not essential, and the step of measuring the background density and the step of correcting with the background density may be omitted.

FIG. 7 is a flow diagram showing an example of a leak test method. The leakage inspection method shown in FIG. 7 is an inspection method when the identification code 520 as shown in FIG. 5 is arranged, and the description of the same configuration as the method shown in FIG. 6 is omitted.

First, the identification code 520 is read to determine the type of the inspection object 500 (step 702). A type-specific illumination area is then selected (step 704) and a leak test is performed according to steps 602 through 616 described above. However, in the concentration measurement of the gas to be detected in step 610, the measurement is performed by controlling the detection light 120 to the irradiation area selected in step 704 (step 706).

In the leak inspection method shown in FIG. 7, even if there are a plurality of types of gas products to be inspected, the type is specified by the identification code 520. Therefore, the inspection area corresponding to the type can be inspected. It is possible to perform inspections by appropriately controlling inspections in which types are mixed.

FIG. 8 is a flow diagram showing an example of a leak test method. The leak inspection method shown in FIG. 8 is a method capable of detecting minute leaks with high sensitivity, and the description of the same configuration as the method shown in FIG. 7 will be omitted.

In the leak inspection method shown in FIG. 8, after difference calculation in step 612 and before leak determination in step 614, leak estimation determination is performed (step 802). Leak estimation judgment is a step for enabling highly accurate measurement when a minute leak is detected, although it does not lead to a leak judgment. If the value is equal to or greater than (the value at which it can be considered that there is a minute leak although it does not lead to the leak determination), steps 804 and 806 are performed. In addition, when the concentration of the gas to be detected is detected in step 802 to the extent that leakage can be determined, the process may proceed to step 616 to notify the presence of leakage.

In step 804, the concentration of the gas to be detected in the same irradiation area where leakage is presumed is re-measured in detail. As detailed re-measurements, reducing the directional displacement speed of the detection light 120 or lengthening the measurement integration time of the gas detector 100 can be mentioned. By decreasing the directional displacement speed of the detection light 120 or by increasing the measurement integration time of the gas detector 100, the measurement accuracy can be increased.

After that, the difference between the background concentration measurement value and the detected gas concentration remeasured value is calculated (step 806), and the leakage determination in step 614 is performed using the difference as the concentration measurement value of the detection gas.

According to the leak inspection method shown in FIG. 8, leak determination is performed with high accuracy only in areas where leakage is likely, and measurement is performed with normal accuracy in other areas. Since concentration measurement with high accuracy generally takes time, it can be said that this inspection method minimizes an increase in inspection time while increasing the accuracy of inspection. That is, according to this inspection method, it is possible to improve the inspection accuracy while shortening the inspection time.

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. For example, in the above embodiment, direction control of the detected light 120 is performed by the direction control mechanism 200 having the base stage 202, the vertical direction control stage 204, the horizontal direction control stage 206, and the direction control section 208. The detection light 120 exiting 102 may be reflected by a single or multiple mirrors, and direction control may be achieved by controlling the angle of reflection of the mirrors. In the above-described embodiment, the identification code 520 is used to determine and select the type of the inspection target 500. However, the image of the inspection target 500 is image-recognized, and the type is determined from the result of the image recognition.・You may choose.

It is obvious to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the description of the scope of claims that forms with such modifications or improvements can also be included in the technical scope of the present invention.

For example, in the above-described embodiment, an example of leak determination with the background measurement gas or inspection gas sealed was explained. good.

DESCRIPTION OF SYMBOLS 10... Leak inspection system 100... Gas detector 102... Light source part 104... Light receiving part 106... Signal detection part 108... Concentration calculation part 110... Display part 120... Detected light 122... Reflected light 200 Direction control mechanism 202 Base stage 204 Vertical control stage 206 Horizontal control stage 208 Direction control unit 300 Control unit 302 Leak determination unit 304 Notification unit 400 Gas supply System 402 Inspection gas cylinder 404 Stop valve 406 Background measurement gas cylinder 408 Stop valve 500 Inspection object 502 Housing 504 Heat exchange unit 506 Combustion unit 508 Controller Portion 510 Gas connection port 512 Line 514 Route 516a to 516d Predetermined area 520 Identification code.

Claims (15)

A gas detector that emits detection light to an object to be inspected, receives light reflected from the object to be inspected, outputs a signal corresponding to the intensity of the received light, and calculates the concentration of the gas to be detected based on the signal. and,
a direction control mechanism for controlling the direction of the detected light;
a leakage determination unit that acquires the concentration of the gas to be detected from the gas detector in conjunction with the direction control mechanism and determines whether the concentration is equal to or greater than a predetermined value;
has
type determination means for reading an identification code placed near the inspection object and determining the type of the inspection object from the read identification code; further comprising type determination means for determining the type of the inspection object;
The direction control mechanism controls the direction so that the detection light is irradiated to an irradiation area specific to the type determined by the type determining means.
leak test system. The leakage inspection system according to claim 1, further comprising a notification unit that notifies the determination result of the leakage determination unit. 3. The leak inspection system according to claim 1, wherein the direction control mechanism controls the direction so that the detection light is scanned over the entire area of the inspection object. 3. The leak inspection system according to claim 1, wherein the direction control mechanism controls the direction such that the detection light is scanned along a predetermined route of the inspection object. 3. The leakage inspection system according to claim 1, wherein the direction control mechanism controls the direction so that the detection light is applied to a single predetermined area of the inspection object. 3. The leak inspection system according to claim 1, wherein the direction control mechanism controls the direction so that the detection light is sequentially applied to a plurality of predetermined regions of the inspection object. When the gas detector detects the estimated leakage concentration exceeding the background concentration, the direction control mechanism changes the directional displacement speed of the detection light in the vicinity of the irradiation position of the detection light at the time when the estimated leakage concentration is detected to: 7. A leak test system according to any one of claims 1 to 6 , wherein the directional displacement speed is controlled slower than normal. 8. Any one of claims 1 to 7 , wherein when the gas detector detects an estimated leakage concentration exceeding a background concentration, the gas detector detects the gas to be detected with a measurement integration time longer than a normal measurement integration time. or the leakage inspection system according to paragraph 1. A leak inspection method using a leak inspection system ,
The leak test system includes:
A gas detector that emits detection light to an object to be inspected, receives light reflected from the object to be inspected, outputs a signal corresponding to the intensity of the received light, and calculates the concentration of the gas to be detected based on the signal. and,
a direction control mechanism for controlling the direction of the detected light;
a leakage determination unit that acquires the concentration of the gas to be detected from the gas detector in conjunction with the direction control mechanism and determines whether the concentration is equal to or greater than a predetermined value;
has
The leak inspection method includes:
a step of introducing an inspection gas containing the gas to be detected into the inspection object;
a step of irradiating the detection light while controlling the direction of the detection light to the inspection object to which the inspection gas has been introduced, and measuring the concentration of the gas to be detected;
determining whether the measured concentration is equal to or greater than a predetermined value;
has
introducing a background measurement gas substantially free of the gas to be detected into the inspection object before the step of introducing the inspection gas;
irradiating the inspection object to which the background measurement gas has been introduced with the detection light to measure the background concentration of the gas to be detected;
In the step of measuring the concentration, a difference between the measured concentration of the gas to be detected and the background concentration is calculated, and the difference is corrected as the concentration of the gas to be detected.
Leak test method. In the step of measuring the concentration, when the concentration measurement value of the gas to be detected is greater than or equal to a predetermined value exceeding the background concentration, the directional displacement speed of the detection light is reduced, or the measurement integration of the gas detector is performed. The leak inspection method according to claim 9 , wherein the time is lengthened. The leak inspection method according to claim 9 or 10, wherein the gas to be detected is a combustible gas, and the concentration of the combustible gas contained in the inspection gas is below the lower explosion limit. The leak inspection method according to claim 11 , wherein the gas to be detected is methane, and the concentration of methane contained in the inspection gas is less than 5 vol%. 13. The leak inspection method according to any one of claims 9 to 12 , wherein if the concentration is determined to be equal to or greater than a predetermined value in the determining step, a notification that there is a gas leak is provided. a first step of introducing an inspection gas containing a gas to be detected into an object to be inspected;
An identification code placed near the inspection object is read, and the type of the inspection object is determined from the read identification code, or an image of the inspection object is acquired, and the inspection object is acquired from the acquired image. a second step of determining the type of
irradiating the inspection object to which the inspection gas has been introduced with the detection light while controlling the direction of the detection light by a direction control mechanism, receiving the reflected light from the inspection object, and obtaining the intensity of the received light; a third step of outputting a signal in response to and calculating the concentration of the gas to be detected based on the signal by the gas detector;
a fourth step of acquiring the concentration of the gas to be detected from the gas detector in conjunction with the direction control mechanism and determining whether the concentration is equal to or greater than a predetermined value;
has
In the third step, the direction control mechanism controls the direction so that the detection light is irradiated to an irradiation region specific to the type determined in the second step.
Leak test method. A gas detector that emits detection light to an object to be inspected, receives light reflected from the object to be inspected, outputs a signal corresponding to the intensity of the received light, and calculates the concentration of the gas to be detected based on the signal. and,
a direction control mechanism for controlling the direction of the detected light;
a leakage determination unit that acquires the concentration of the gas to be detected from the gas detector in conjunction with the direction control mechanism and determines whether the concentration is equal to or greater than a predetermined value;
has
a first mode for measuring the background concentration of the target gas by irradiating the inspection object into which the background measurement gas that does not substantially contain the target gas is irradiated with the detection light;
a second mode for measuring the concentration of the gas to be detected by irradiating the inspection object into which the inspection gas containing the gas to be detected is introduced with the detection light while controlling the direction of the detection light;
A third mode for judging whether the measured concentration is equal to or higher than a predetermined value, calculating the difference between the concentration measurement value of the detection target gas and the background concentration, and correcting the difference as the concentration of the detection target gas. the third mode;
having
leak test system.

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