Spray unit for leakage inspection, leakage inspection system, and leakage inspection method

Abstract

To provide a spray unit for leakage inspection that allows mist of fluorescence inspection liquid to reach a distant place with respect to piping of a building.SOLUTION: A spray unit for leakage inspection 30 comprises: an inspection liquid pipe 48 that supplies fluorescence inspection liquid; a spray air pipe 46 that supplies spray air; a two-fluid nozzle 44 that mixes the fluorescence inspection liquid and the spray air and discharges mist of the fluorescence inspection liquid; and a housing 40 that accommodates the inspection liquid pipe 48, spray air pipe 46, and two-fluid nozzle 44. The housing 40 includes a discharge port 50 that is formed in a discharge direction of the two-fluid nozzle 44 and discharges the mist to the outside of the housing 40, and a dilution port 62 that introduces assist air to a mixing chamber 42 inside the housing 40.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a spray unit for leak inspection, a leak inspection system, and a leak inspection method. [Background technology]

[0002] Japanese Patent Application Laid-Open No. 2023-039662 (Patent Document 1) discloses a method for detecting leaks in compressed air piping by introducing a mist of fluorescent test liquid into the piping and detecting the location of the leak by fluorescence generated by irradiating it with ultraviolet light. In this method, a lubricator is filled with the fluorescent test liquid and a mist of the fluorescent test liquid is generated. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-039662 Summary of the Invention [Problem to be solved by the invention]

[0004] However, it was found that when the flow rate and pressure of the compressed air supplied by the lubricator is low, it is difficult for the mist of fluorescent inspection liquid to reach long distances into the building's piping.

[0005] In particular, the refrigerant pipes of air conditioning equipment have a relatively large diameter, which reduces the flow rate of compressed air inside the pipes. As a result, the mist of fluorescent test liquid generated by the lubricator adheres to the inner wall of the pipes before reaching a long distance.

[0006] The present disclosure aims to solve the above-mentioned problems. [Means for solving the problem]

[0007] A first aspect of the present disclosure is a spray unit for leak inspection that sprays a fluorescent test liquid having a fluorescent dye dissolved therein into the inside of a pipe that is to be inspected for leaks, the spray unit comprising: a two-fluid nozzle that mixes the fluorescent test liquid with spray air and ejects a mist of the fluorescent test liquid; a test liquid pipe that supplies the fluorescent test liquid to the two-fluid nozzle; a spray air pipe that supplies the spray air to the two-fluid nozzle; and a housing that accommodates the test liquid pipe, the spray air pipe, and the two-fluid nozzle, the housing being formed in the ejection direction of the two-fluid nozzle and comprising: a discharge port that ejects the mist to the outside of the housing; and a dilution port that introduces assist air into a mixing chamber inside the housing.

[0008] A second aspect of the present disclosure is a leak inspection system comprising a leak inspection spray unit according to the first aspect, an air supply source that supplies the spray air to the spray air piping, and an inspection liquid tank that contains the fluorescent inspection liquid and supplies the fluorescent inspection liquid to the inspection liquid piping.

[0009] A third aspect of the present disclosure is a leak inspection method using the leak inspection system according to the second aspect, comprising the steps of connecting the leak inspection spray unit to the piping to be inspected for leaks, generating the mist using the leak inspection spray unit and circulating the mist together with the spray air through the piping to be inspected for leaks, and irradiating the outside of the piping with ultraviolet light to detect whether or not there is a leak of the fluorescent inspection liquid. [Effects of the Invention]

[0010] According to the present disclosure, even when a low-power air compressor is used, it is possible to make the mist of the fluorescent inspection liquid reach pipes located far away. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is an explanatory diagram showing an example of connection between the leak inspection system according to the first embodiment and a piping system to be inspected. [Figure 2]FIG. 2 is a configuration diagram of the leak inspection system of FIG. [Figure 3] FIG. 3 is a cross-sectional view of the leak detection spray unit of FIG. [Figure 4] FIG. 4 is a perspective view of the leak test spray unit of FIG. [Figure 5] FIG. 5 is a diagram for explaining the operation of the leak inspection spray unit of FIG. [Figure 6] FIG. 6 is a graph showing the particle size distribution of the mist generated in Experimental Example 1, with particle size on the horizontal axis and the number of particle counts on the vertical axis. [Figure 7] FIG. 7A is a configuration diagram of a test liquid supply unit according to a first modification of the first embodiment, and FIG. 7B is a configuration diagram of a test liquid supply unit according to a second modification of the first embodiment. [Figure 8] FIG. 8 is a configuration diagram of a leak inspection system according to the second embodiment. [Figure 9] FIG. 9 is a configuration diagram of a leak inspection system according to the third embodiment. [Figure 10] FIG. 10 is an explanatory diagram showing an example of the configuration of the recovery flow path in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] (First embodiment) As shown in Fig. 1, a leak detection system 10 according to this embodiment is connected to a piping system 12 and is used to detect leaks in pipes 16, connection points 14, valves 18, and the connection points of these components. The piping system 12 has a plurality of pipes 16 connected to each other at connection points 14. A plurality of valves 18 are attached to predetermined locations of the piping system 12. The piping system 12 is, for example, a water pipe that supplies purified water, or an air conditioning pipe that circulates a refrigerant between a heat source device and an air conditioner (indoor unit) located indoors in a building.

[0013] The leak detection system 10 is connected to a first end 12a of the piping system 12, and the exhaust unit 20 is connected to a second end 12b of the piping system 12. The exhaust unit 20 includes a filter 22 and an exhaust port 24. The filter 22 separates and collects the mist of the fluorescent test liquid from the compressed air. The exhaust port 24 discharges the compressed air supplied from the leak detection system 10.

[0014] 2, the leak inspection system 10 includes an air supply source 26, a first adjustment unit 28, a leak inspection spray unit 30, and an inspection liquid supply unit 31. The air supply source 26 is, for example, an air compressor, and generates compressed air. The air supply source 26 is connected to the leak inspection spray unit 30 through a first pipe 34, and supplies compressed air for spraying (spray air) to the leak inspection spray unit 30.

[0015] A first adjustment unit 28 is provided on the first piping 34. The first adjustment unit 28 adjusts the pressure and flow rate of the compressed air supplied to the leak inspection spray unit 30 to predetermined values. The first adjustment unit 28 has a first pressure reducing valve 36 and a first flow rate adjustment valve 38. The first pressure reducing valve 36 is located upstream of the first flow rate adjustment valve 38 (on the side closer to the air supply source 26). The first pressure reducing valve 36 adjusts the pressure of the compressed air to within a predetermined range. The first flow rate adjustment valve 38 is located downstream of the first pressure reducing valve 36 and adjusts the flow rate of the compressed air supplied to the leak inspection spray unit 30 to within a predetermined range.

[0016] As shown in FIG. 3, the leak test spray unit 30 includes a housing 40, a mixing chamber 42, a two-fluid nozzle 44, a spray air pipe 46, a test liquid pipe 48, and a discharge port 50. The housing 40 has a cylindrical body 52, a base end wall 54, and a tip end wall 56. The cylindrical body 52 is formed in a circular shape when viewed in the axial direction (see FIG. 4) and extends cylindrically in the axial direction. The axial dimension of the cylindrical body 52 can be, for example, 60 mm to 100 mm. The inner diameter of the cylindrical body 52 can be 80 mm to 100 mm. The cylindrical body 52 may also be formed in a polygonal shape. The polygonal cylindrical body 52 may be formed rotationally symmetrically with respect to the central axis C.

[0017] The base end wall 54 is located at the base end of the housing 40 in the axial direction, and covers and closes the base end of the cylindrical body 52. ​​The tip end wall 56 is located at the tip of the cylindrical body 52 opposite the base end wall 54 in the axial direction, and covers the tip of the cylindrical body 52. ​​The mixing chamber 42 is formed inside the cylindrical body 52, the base end wall 54, and the tip end wall 56.

[0018] 3 and 4, the base end wall 54 has a spray air port 58, a test liquid port 60, and a plurality of dilution ports 62. The spray air port 58 is disposed at a position offset outward from the central axis C of the housing 40. The spray air port 58 has a first connector 58a extending from the base end wall 54 toward the base end. The first connector 58a is connected to the first piping 34 (see FIG. 2). The spray air piping 46 is connected to the tip side of the spray air port 58 (inside the housing 40).

[0019] The test liquid port 60 is disposed at a position on the central axis C of the housing 40. The test liquid port 60 includes a second connector 60a extending from the base end wall 54 toward the base end. A second piping 64 (see FIG. 2) is connected to the second connector 60a. The test liquid piping 48 is connected to the tip end side of the test liquid port 60.

[0020] The dilution port 62 is disposed at a position away from the central axis C of the housing 40. A plurality of dilution ports 62 may be provided. In the example shown in FIG. 4, three dilution ports 62 are provided to surround the test liquid port 60. Each dilution port 62 has a third connector 62a protruding from the base end wall 54 toward the base end.

[0021] The tip side of the dilution port 62 opens toward the mixing chamber 42 and discharges assist air (air for dilution) into the mixing chamber 42. The opening position of the dilution port 62 is not limited to the base end wall 54, and it may be configured to open in the cylindrical body 52. ​​However, it is preferable that the opening position of the dilution port 62 be located closer to the base end than the axial position of the bi-fluid nozzle 44. Such an arrangement does not interfere with the discharge of the mist sprayed in a spreading manner from the bi-fluid nozzle 44.

[0022] In this embodiment, the base end of the third connector 62a is not connected to anything and is open to the atmosphere, allowing the atmosphere to be taken in directly. When mist is sprayed from the two-fluid nozzle 44, the air inside the mixing chamber 42 flows out toward the tip, creating negative pressure inside the mixing chamber 42. When negative pressure is created in the mixing chamber 42, the dilution port 62 introduces outside air into the mixing chamber 42 as assist air.

[0023] The assist air taken into the mixing chamber 42 from the dilution port 62 mixes with the mist sprayed from the two-fluid nozzle 44, reducing the density of the droplets of the fluorescent test liquid. The assist air also directs the mist, which is sprayed at a wide angle from the two-fluid nozzle 44 and remains inside the mixing chamber 42, toward the discharge port 50, thereby preventing mist loss and allowing more mist to be efficiently discharged from the discharge port 50. Furthermore, the assist air suppresses a decrease in the flow velocity of the airflow containing the mist within the piping 16, allowing the mist to reach long distances within the piping 16 more quickly.

[0024] The dilution port 62 is preferably disposed near the inner wall of the cylindrical body 52 and disposed so that the center of the flow hits the tip wall 56. Such a dilution port 62 generates a flow of assist air that covers the inner wall of the cylindrical body 52, suppressing the adhesion of mist to the inner wall of the cylindrical body 52. ​​In addition, the assist air that flows along the inner wall of the cylindrical body 52 hits the tip wall 56, generating a flow that is drawn inward near the tip wall 56, and efficiently directs the mist that has accumulated near the tip wall 56 to the discharge port 50.

[0025] The flow path cross-sectional area of ​​the multiple dilution ports 62 is larger than the effective flow path cross-sectional area of ​​the spray air piping 46 and the spray air port 58. This allows the leak inspection spray unit 30 to flow a larger amount of assist air than the flow rate of the spray air, thereby suppressing a decrease in the flow rate of the air flow containing mist inside the piping 16.

[0026] The discharge port 50 is formed by penetrating the tip wall 56 in the axial direction. The discharge port 50 is disposed on an extension of the discharge center of the two-fluid nozzle 44, and allows the mist discharged from the two-fluid nozzle 44 to pass through. In this embodiment, the discharge port 50 is formed as a hole centered on the central axis C of the casing 40. The cross section of the discharge port 50 perpendicular to the central axis C may be circular. The inner diameter of the discharge port 50 can be, for example, in the range of 10 mm to 60 mm. The inner diameter of the discharge port 50 can be adjusted appropriately depending on the axial position of the two-fluid nozzle 44.

[0027] The inner diameter of the discharge port 50 may be smaller than the diameter of the circle formed at the tip wall 56 by the conical area sprayed at a predetermined spread angle from the two-fluid nozzle 44 (see FIG. 5). Even with this configuration, the mist can be efficiently discharged from the discharge port 50 by the use of assist air.

[0028] A threaded structure (not shown) is provided on the inner periphery of the discharge port 50. A piping connector can be connected to the threaded structure. The piping connector is used to connect the leak inspection spray unit 30 to the piping system 12.

[0029] The spray air pipe 46 has its base end connected to the spray air port 58 and extends axially toward its tip. The spray air pipe 46 is bent toward the central axis C at a bent portion 46a provided near the tip and is connected to the bi-fluid nozzle 44. The spray air pipe 46 supplies spray air to the bi-fluid nozzle 44.

[0030] The base end of the test liquid piping 48 is connected to the test liquid port 60, and extends axially from the test liquid port 60 along the central axis C. The tip of the test liquid piping 48 is connected to the two-fluid nozzle 44. The spray air piping 46 and the test liquid piping 48 are formed from a hard material, and support the two-fluid nozzle 44 at a distance from the housing 40.

[0031] As shown in FIG. 3 , the bi-fluid nozzle 44 mixes the fluorescent test liquid supplied from the test liquid pipe 48 with the spray air supplied from the spray air pipe 46 to generate a mist of the fluorescent test liquid. The bi-fluid nozzle 44 has a central flow passage 44a extending axially and connected to the test liquid pipe 48 at its base end, and radial flow passages 44b extending radially and communicating with the central flow passage 44a. The spray air pipe 46 is connected to the radial flow passages 44b, through which spray air is supplied. The bi-fluid nozzle 44 ejects a mist of the fluorescent test liquid into a conical region centered on an extension of the central flow passage 44a toward its tip. The bi-fluid nozzle 44 is located at the center of the cylindrical body 52 in a cross section perpendicular to the central axis C. Therefore, the central flow passage 44a is coaxial with the central axis C, and the mist is ejected along the central axis C.

[0032] Here, the axial position of the bi-fluid nozzle 44 is represented by the distance d between the tip of the bi-fluid nozzle 44 and the tip wall 56. The distance d is defined as 0 when the position (proximal position) 56a of the tip wall 56 is on the proximal side. The value of the distance d increases as the tip of the bi-fluid nozzle 44 moves farther from the proximal position 56a of the tip wall 56 toward the proximal end. The distance d of the bi-fluid nozzle 44 can be set to, for example, −1 mm to 45 mm. A distance d of −1 mm means that the tip of the bi-fluid nozzle 44 is positioned 1 mm further distal than the proximal position 56a of the tip wall 56. In this case, part of the tip of the bi-fluid nozzle 44 may be inserted into the discharge port 50.

[0033] The axial position of the bi-fluid nozzle 44 may be near the center of the axial direction of the housing 40. In this case, the amount of mist that is discharged from the bi-fluid nozzle 44 and remains inside the mixing chamber 42 changes, thereby making it possible to further increase the effect of the assist air.

[0034] The test liquid supply unit 31 includes a test liquid tank 32 and a second pipe 64. The test liquid tank 32 is a container that contains a fluorescent test liquid. The test liquid tank 32 is connected to the leak test spray unit 30 through the second pipe 64. The fluorescent test liquid is sucked out of the test liquid tank 32 by the two-fluid nozzle 44.

[0035] The fluorescent test solution contained in the test solution tank 32 is an aqueous solution containing fluorescent dyes dissolved in water. The fluorescent dyes may be green, blue, or red, either singly or in combination. Examples of green fluorescent dyes include riboflavin, fluorescein, acridine orange, phloxine B (Red No. 104), and lycopene. Examples of blue fluorescent dyes include a mixture of formylmethylflavin and lumichrome, quinine, pyrene, anthocyanin, and umbelliferone. Examples of red fluorescent dyes include chlorophyll, rhodamine B, acid red (Red No. 106), eosin, cochineal pigment, tannin, phycocyanin (spirulina pigment), carthamin (safflower pigment), phycoerythrin, erythrosine (Red No. 3), and rose bengal (Red No. 105).

[0036] The mixture of riboflavin, formylmethylflavin, and lumichrome loses its fluorescence when the water evaporates, simplifying cleaning after the test is completed. The fluorescent dyes listed above are substances used as food additives, are safe for humans and the environment, and decompose and disappear in a relatively short time. This allows for easy disposal of the recovered fluorescent test solution. The fluorescent test solution may contain preservatives such as parabens. The fluorescent test solution may also contain a surfactant to improve wettability to the inner surface of the pipe 16.

[0037] The leak inspection system 10 of this embodiment is configured as described above. A leak inspection method using the leak inspection system 10 will be described below. Note that the leak inspection is performed, for example, after the piping system 12 is installed in a building and before it is put into use. The leak inspection can also be performed when inspecting the piping system 12.

[0038] 1, a leak inspection system 10 is connected to one end of a piping system 12. An exhaust unit 20 is connected to a predetermined end of the piping system 12.

[0039] Next, the supply of atomizing air begins through the air supply source 26. As shown in Figure 5, the atomizing air flows into the atomizing air port 58 through the first pipe 34 and is supplied to the bi-fluid nozzle 44 through the atomizing air pipe 46. The atomizing air that flows into the bi-fluid nozzle 44 is discharged toward the axial tip of the bi-fluid nozzle 44 through the central flow path 44a of the bi-fluid nozzle 44. The discharge of the atomizing air generates negative pressure in the central flow path 44a, and this negative pressure causes the fluorescent test liquid to be sucked out of the test liquid tank 32 through the second pipe 64 and the test liquid pipe 48, and the fluorescent test liquid is supplied to the central flow path 44a.

[0040] The fluorescent test liquid is mixed with spray air in the central flow passage 44a inside the bi-fluid nozzle 44, and is turned into mist, which is then discharged from the bi-fluid nozzle 44 toward the tip in the axial direction. The mist discharged from the bi-fluid nozzle 44 is discharged together with the spray air from the discharge port 50. The flow of the mixed fluid of mist and spray air creates negative pressure inside the mixing chamber 42. This negative pressure causes outside air to flow into the mixing chamber 42 through the dilution port 62 as assist air.

[0041] The assist air flows from the base end of the bi-fluid nozzle 44 toward the tip end while spreading inside the mixing chamber 42. A portion of the assist air strikes the tip wall 56, generating turbulence inside the mixing chamber 42 near the tip wall 56. The flow of assist air prevents the mist from adhering to the inner wall of the housing 40, thereby suppressing mist reduction. The assist air also dilutes the mist and directs the mist remaining inside the mixing chamber 42 toward the discharge port 50, thereby efficiently discharging particles with a particle size of 1 μm to 10 μm, which can reach long distances, from the discharge port 50. Note that mist with a particle size less than 1 μm easily evaporates and cannot reach long distances inside the piping system 12. Furthermore, mist with a particle size greater than 10 μm falls within the piping 16 within a relatively short distance due to the effects of gravity, making it difficult for a low-power air compressor to deliver the mist long distances inside the piping 16.

[0042] In this way, the mist diluted with assist air in the mixing chamber 42 and the discharge port 50 flows into the piping system 12 shown in Figure 1 and circulates through the piping 16. The mist generated by the leak detection spray unit 30 flows like smoke, spreading to each of the piping 16 that branches off inside the piping system 12. Some of the mist adheres to the inner surface of each piping 16. Other parts of the mist and the compressed air are discharged from the exhaust section 20. The mist that flows into the exhaust section 20 is removed by the filter 22, and only the compressed air is discharged into the atmosphere from the exhaust port 24.

[0043] There may be a leak in the piping system 12. The leak may be, but is not limited to, a location where the joints connecting the pipes 16 are not tight enough, or a damaged part of the pipes 16, the connection point 14, the valve 18, or the like. If there is a leak in the piping system 12, mist leaks from the leak along with compressed air. As a result, the droplets that make up the mist adhere to the leak and its surroundings, staining the leak with a fluorescent dye.

[0044] Next, each part of the piping system 12 is irradiated with ultraviolet light. In this process, the presence or absence of fluorescent points on the surface of the piping system 12 is checked by irradiating ultraviolet light. The location of the leak is identified by detecting the fluorescence. If a leak is found, work such as tightening joints or replacing parts is performed, and a leak inspection is performed again. Thereafter, the leak inspection system 10 and the exhaust unit 20 are removed from the piping system 12, and the leak inspection is completed.

[0045] (Experimental Example 1) In Experimental Example 1, compressed air was supplied to the two-fluid nozzle 44 of the leak detection spray unit 30 shown in Figure 3 at a pressure of 0.3 MPa and a flow rate of 22 L / min to generate a mist of fluorescent test liquid. The particle size distribution of the mist discharged from the leak detection spray unit 30 was measured using a particle counter. As a result, as shown in Figure 6, it was confirmed that the leak detection spray unit 30 of this embodiment can generate a mist of fluorescent test liquid containing many fine particles with particle sizes of 1 μm to 10 μm that can reach long distances.

[0046] (Modification 1 of the first embodiment) As shown in FIG. 7A, this modified example has a test liquid supply unit 31A according to another example configuration. The test liquid supply unit 31A has a pump 66 in the second pipe 64 connecting the leak test spray unit 30 and the test liquid tank 32. The pump 66 pressurizes the fluorescent test liquid in the test liquid tank 32 and sends it toward the two-fluid nozzle 44. This modified example can supply the fluorescent test liquid to the two-fluid nozzle 44 at a constant pressure and flow rate, thereby increasing the flow rate of the fluorescent test liquid and increasing the amount of mist generated. Furthermore, this modified example can stabilize the spray conditions of the two-fluid nozzle 44 and stabilize the particle size of the mist.

[0047] (Modification 2 of the first embodiment) As shown in FIG. 7B, this modified example includes a test liquid supply unit 31B according to yet another exemplary configuration. The test liquid supply unit 31B includes a pressurizing air source 68 connected to the test liquid tank 32. The pressurizing air source 68 pressurizes the fluorescent test liquid by supplying pressurizing air (compressed air) to the test liquid tank 32. The fluorescent test liquid in the test liquid tank 32 is pressurized by the pressure of the pressurizing air and sent to the leak test spray unit 30. This modified example increases the flow rate of the fluorescent test liquid supplied to the two-fluid nozzle 44, thereby increasing the amount of mist generated. Furthermore, this modified example can stabilize the spray conditions of the two-fluid nozzle 44, enabling stable generation of mist.

[0048] (Second embodiment) 8, in the leak inspection system 10A of this embodiment, part of the compressed air from the air supply source 26 is supplied to the dilution port 62 of the leak inspection spray unit 30. In the configuration of the leak inspection system 10A, the same components as those in the leak inspection system 10 of the first embodiment (see FIG. 2) are designated by the same reference numerals, and detailed description thereof will be omitted.

[0049] The leak inspection system 10A includes a third pipe 70 branching off from the first pipe 34. The upstream end of the third pipe 70 communicates with the first pipe 34 at a branch point 70a located upstream of the first pressure reducing valve 36. The downstream end of the third pipe 70 is connected to the dilution port 62. The leak inspection spray unit 30 has three dilution ports 62. The third pipe 70 branches off into three near the leak inspection spray unit 30 and is connected to each of the three dilution ports 62. The third pipe 70 supplies a portion of the compressed air from the air supply source 26 to the leak inspection spray unit 30 as assist air.

[0050] A second adjustment unit 72 is provided midway along the third piping 70. The second adjustment unit 72 adjusts the pressure and flow rate of the assist air supplied to the mixing chamber 42 through the dilution port 62 to predetermined values. The second adjustment unit 72 includes a second pressure reducing valve 74 and a second flow rate adjustment valve 76. The second pressure reducing valve 74 adjusts the pressure of the assist air to a predetermined value. The second flow rate adjustment valve 76 adjusts the flow rate of the assist air to a predetermined value.

[0051] In the leak inspection system 10A, the configurations of the leak inspection spray unit 30 and the inspection liquid supply unit 31 are the same as those of the leak inspection system 10 of the first embodiment.

[0052] The leak detection system 10A of this embodiment is configured as described above. The leak detection system 10A can increase the flow rate of the assist air, and can spray a larger amount of mist at a faster flow rate into the piping system 12 (see FIG. 1). As a result, the leak detection system 10A can increase the flow rate of the mist inside the piping 16, and can further extend the reach of the mist.

[0053] (Third embodiment) 9, the leak inspection system 10B of this embodiment is provided with a recovery flow path 78 that recovers the fluorescent inspection liquid adhering to the inner wall of the mixing chamber 42 and the piping 16 near the leak inspection spray unit 30. In the configuration of the leak inspection system 10B, the same components as those in the leak inspection system 10 of the first embodiment (see FIG. 2) or the leak inspection system 10A of the second embodiment (see FIG. 8) are designated by the same reference numerals, and detailed description thereof will be omitted.

[0054] 10, the recovery flow path 78 has a first recovery flow path 78a and a second recovery flow path 78b. The first recovery flow path 78a connects a drain hole 80 formed in the bottom of the housing 40 of the leak test spray unit 30 to the test liquid tank 32. The first recovery flow path 78a returns the fluorescent test liquid adhering to the inner wall of the mixing chamber 42 of the leak test spray unit 30 to the test liquid tank 32.

[0055] The second recovery flow path 78b is connected to a connector 82 that connects the leak detection spray unit 30 and the piping system 12. The connector 82 has a main flow path 82a and a drain port 82b that branches off from the bottom of the main flow path 82a. The drain port 82b recovers and discharges the fluorescent test liquid that has adhered to the inside of the connector 82 and to the inner wall of the piping system 12 near the leak detection spray unit 30. The second recovery flow path 78b connects the drain port 82b to the test liquid tank 32, and allows the fluorescent test liquid collected in the drain port 82b to flow into the test liquid tank 32.

[0056] The leak inspection system 10B of this embodiment is configured as described above. The leak inspection system 10B can collect and reuse the fluorescent inspection liquid that has adhered to the inside of the leak inspection spray unit 30 or the inner surface of the piping 16 in close proximity to the leak inspection spray unit 30, and therefore has excellent utilization efficiency of the fluorescent inspection liquid.

[0057] The following additional notes are further disclosed regarding the above embodiment.

[0058] (Appendix 1) The present disclosure relates to a leak inspection spray unit (30) that sprays a fluorescent test liquid having a dissolved fluorescent dye into the inside of a pipe (16) that is the subject of a leak inspection, and includes a two-fluid nozzle (44) that mixes the fluorescent test liquid with spray air and ejects a mist of the fluorescent test liquid, a test liquid pipe (48) that supplies the fluorescent test liquid to the two-fluid nozzle, a spray air pipe (46) that supplies the spray air to the two-fluid nozzle, and a housing (40) that houses the test liquid pipe, the spray air pipe, and the two-fluid nozzle, the housing being formed in the ejection direction of the two-fluid nozzle and including a discharge port (50) that ejects the mist to the outside of the housing and a dilution port (62) that introduces assist air into a mixing chamber (42) inside the housing.

[0059] The above-mentioned leak detection spray unit can spray the mist of the fluorescent detection liquid to reach pipes located far away, even when a low-power air compressor is used as the air supply source.

[0060] (Appendix 2) In the spray unit for leak inspection described in Appendix 1, the two-fluid nozzle may be supported at a distance from the housing by the spray air piping and the test liquid piping. This spray unit for leak inspection can efficiently cause the mist discharged from the two-fluid nozzle and remaining inside the housing to flow into the piping to be inspected.

[0061] (Appendix 3) In the spray unit for leak inspection described in Appendix 2, the housing may include a cylindrical body (52) extending in an axial direction along the discharge direction and covering the two-fluid nozzle, a tip wall (56) covering the tip side of the cylindrical body, and a base end wall (54) covering the base end side of the cylindrical body opposite the tip side, and the dilution port may be provided in the base end wall. In this spray unit for leak inspection, by providing the dilution port in the base end wall, the assist air flows while spreading, and the mist can be efficiently flowed into the piping to be inspected.

[0062] (Appendix 4) In the leak detection spray unit according to Supplementary Note 3, the two-fluid nozzle may be inserted into the discharge port of the tip wall. This leak detection spray unit can cause a larger amount of mist of the generated fluorescent test liquid to flow into the piping to be inspected.

[0063] (Appendix 5) In the spray unit for leak detection described in Supplementary Note 3, the two-fluid nozzle may be located at the center of the housing in a cross section perpendicular to the axial direction. This spray unit for leak detection can efficiently dilute the mist with assist air inside the housing.

[0064] (Appendix 6) In the leak detection spray unit described in Appendix 3, the base end wall may have a test liquid port (60) for supplying the fluorescent test liquid to the test liquid piping, and a plurality of the dilution ports may be provided surrounding the test liquid port. This leak detection spray unit prevents mist from adhering to the inner wall of the housing and allows more mist to flow into the piping to be inspected.

[0065] (Appendix 7) In the leak detection spray unit according to any one of Supplementary Notes 1 to 6, the dilution port may be open to the atmosphere, and outside air may be introduced as the assist air. This leak detection spray unit can supply a large amount of mist to the piping to be inspected with a small amount of compressed air, and can supply the mist over a longer distance by suppressing a decrease in flow velocity in the piping to be inspected.

[0066] (Appendix 8) In the leak detection spray unit according to any one of Supplementary Notes 1 to 7, the dilution port may introduce compressed air as assist air. In this leak detection spray unit, the flow rate of the assist air is increased by the compressed air, and the flow rate of the airflow containing the mist in the piping to be inspected is increased, thereby enabling the mist to be supplied over a longer distance.

[0067] (Appendix 9) In the spray unit for leak inspection described in any one of Supplementary Notes 1 to 8, the flow rate of the assist air introduced into the dilution port may be greater than the flow rate of the spray air supplied to the two-fluid nozzle. This spray unit for leak inspection suppresses a decrease in the flow rate of the airflow containing the mist inside the piping to be inspected, and allows the mist to reach a longer distance.

[0068] (Appendix 10) A leak detection system (10, 10A, 10B) of the present disclosure includes a leak detection spray unit according to any one of Supplementary Notes 1 to 9, an air supply source (26) that supplies the spray air to the spray air pipe, and a test liquid tank (32) that stores the fluorescent test liquid and supplies the fluorescent test liquid to the test liquid pipe. This leak detection system can spray a mist of the fluorescent test liquid over a long distance even when a low-power air compressor is used.

[0069] (Appendix 11) The leak detection system described in Appendix 10 may further include a recovery flow path (78) for recovering the fluorescent test liquid adhering to the piping to be inspected inside the housing or near the housing and returning the fluorescent test liquid to the test liquid tank. This leak detection system can reduce waste of the fluorescent test liquid.

[0070] (Appendix 12) The present disclosure may provide a leak inspection method using the leak inspection system described in Appendix 10 or 11, comprising the steps of connecting the leak inspection spray unit to the pipe to be inspected for leaks, generating the mist using the leak inspection spray unit and circulating the mist together with the sprayed air through the pipe to be inspected for leaks, and irradiating the outside of the pipe with ultraviolet light to detect the presence or absence of leakage of the fluorescent inspection liquid. This leak inspection method enables leak inspection of large-scale pipes even when a low-output air compressor is used.

[0071] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments. [Explanation of symbols]

[0072] 10, 10A, 10B...Leak inspection system 16...Piping 26...Air supply source 30...Leak inspection spray unit 32...Inspection liquid tank 40...Housing 42...Mixing chamber 44...Two-fluid nozzle 46...Atomizing air piping 48...Test liquid piping 50...Discharge port 52...Cylinder 54...Proximal wall 56...Tip wall 62...Dilution port 78...Recovery channel

Claims

1. A leak inspection spray unit that sprays a fluorescent inspection liquid containing a dissolved fluorescent dye into the inside of a pipe that is to be inspected for leaks, a two-fluid nozzle that mixes the fluorescent inspection liquid with spray air and discharges a mist of the fluorescent inspection liquid; a test liquid pipe for supplying the fluorescent test liquid to the two-fluid nozzle; a spray air pipe that supplies the spray air to the two-fluid nozzle; a housing that houses the test liquid pipe, the spray air pipe, and the two-fluid nozzle, The housing includes: a discharge port formed in a discharge direction of the two-fluid nozzle and configured to discharge the mist to the outside of the housing; A spray unit for leak testing, comprising: a dilution port for introducing assist air into a mixing chamber inside the housing.

2. 2. The spray unit for leak detection according to claim 1, The two-fluid nozzle is supported at a distance from the housing by the spray air pipe and the test liquid pipe.

3. 3. The spray unit for leak detection according to claim 2, The housing includes: a cylindrical body extending in an axial direction along the discharge direction and covering the two-fluid nozzle; a tip wall covering the tip side of the cylindrical body; a base end wall covering a base end side opposite to the tip end side of the cylindrical body, The dilution port is provided in the proximal end wall.

4. 4. The spray unit for leak detection according to claim 3, The two-fluid nozzle is inserted into the discharge port of the tip wall.

5. 4. The spray unit for leak detection according to claim 3, The two-fluid nozzle is located at the center of the housing in a cross section perpendicular to the axial direction.

6. 4. The spray unit for leak detection according to claim 3, the base end wall has a test liquid port for supplying the fluorescent test liquid to the test liquid pipe; A spray unit for leak inspection, wherein a plurality of the dilution ports are provided so as to surround the periphery of the inspection liquid port.

7. 2. The spray unit for leak detection according to claim 1, The dilution port is open to the atmosphere, and outside air is introduced as the assist air.

8. 2. The spray unit for leak detection according to claim 1, The dilution port introduces compressed air as the assist air.

9. 2. The spray unit for leak detection according to claim 1, A spray unit for leak inspection, wherein the flow rate of the assist air introduced into the dilution port is greater than the flow rate of the spray air supplied to the two-fluid nozzle.

10. A spray unit for leak inspection according to any one of claims 1 to 9, an air supply source that supplies the spray air to the spray air pipe; a test liquid tank that stores the fluorescent test liquid and supplies the fluorescent test liquid to the test liquid pipe.

11. 11. The leak detection system of claim 10, The leak inspection system further comprises a recovery flow path for recovering the fluorescent inspection liquid adhering to the pipe that is the subject of leak inspection inside the housing or in the vicinity of the housing, and returning the fluorescent inspection liquid to the inspection liquid tank.

12. A leak inspection method using the leak inspection system according to claim 10, comprising: connecting the leak test spray unit to the pipe to be tested for leaks; a step of generating the mist using the leak inspection spray unit and circulating the mist together with the spray air through the piping that is the target of the leak inspection; and irradiating the outside of the piping with ultraviolet light to detect whether or not the fluorescent inspection liquid is leaking.

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