WO2020138425A1

WO2020138425A1 - Search gas mixing method

Info

Publication number: WO2020138425A1
Application number: PCT/JP2019/051444
Authority: WO
Inventors: 直樹吉良
Original assignee: 株式会社キッツ
Priority date: 2018-12-27
Filing date: 2019-12-27
Publication date: 2020-07-02

Abstract

Provided is a search gas mixing method with which a diffusive gas and an inert gas are mixed in a short time by small and simplified equipment to safely produce a search gas for leakage inspection is safely generated, so that the inspection of leakage from a pressure apparatus can be simply and efficiently performed. A search gas composed of a diffusive gas and an inert gas is used, one of the gases is sealed in a sample 1 with a pressure corresponding to a predetermined concentration, and then, the other of the gases raises the pressure inside the sample 1 up to an inspection pressure. Thus, the inspection of leakage from the pressure apparatus is performed with the search gas having the predetermined concentration.

Description

Search gas mixing method

The present invention relates to a method of mixing a search gas used for a pressure test or a leak test of a pressure resistant device such as a valve or a pressure resistant component.

For example, pressure-resistant equipment such as valves and various pressure-resistant parts require high pressure resistance and airtightness. Therefore, to confirm strength and leakage before shipment, pressure resistance inspection and leak inspection using search gas are required. Is carried out. In the inspection using these search gases, a pressure inspection and a leakage inspection are generally performed by supplying the search gas into the work (sample) and detecting the leakage of the gas to the outside of the work with a sensor. For this reason, a diffusible gas whose leak is easily detected by a sensor is used as the search gas, and hydrogen gas is often used as the diffusible gas.

In this case, in order to increase the safety by lowering the chemical reactivity of high-concentration hydrogen gas, and to minimize the amount of hydrogen gas used during leak inspection as much as possible, high-concentration hydrogen gas is usually diluted. The diluted hydrogen gas is used as a search gas. In general, an inert gas is used as the diluting gas, and nitrogen is generally used as the inert gas for diluting the hydrogen gas.

As a device for providing a search gas by mixing this type of diffusible gas and an inert gas, for example, a diluted hydrogen gas generation device of Patent Document 1 is disclosed. This apparatus has a hydrogen gas supply passage, a dilution gas supply passage, a mixing tank, and a gas flow rate proportional control means. Then, hydrogen is generated by electrolysis by the hydrogen generation source, and this hydrogen is guided to the mixing tank by the hydrogen gas supply passage. On the other hand, the diluting gas is supplied from the diluting gas supply source, and the nitrogen gas in the diluting gas is guided to the mixing tank by the diluting gas supply passage. The hydrogen gas and nitrogen gas introduced into these mixing tanks are mixed in this mixing tank to generate diluted hydrogen gas (mixed gas). As described above, this device mixes hydrogen gas and nitrogen gas in separate mixing tanks to generate a mixed gas, and sends the mixed gas as a search gas to the inside of the work to perform a leak inspection. Is.

The gas flow rate proportional control means is composed of a first mass flow controller provided in the hydrogen gas supply passage and a second mass flow controller provided in the dilution gas supply passage. Each flow rate control is performed, and the mixing ratio of the diluted hydrogen gas is set by this flow rate control.

Japanese Patent Laid-Open No. 2018-65073

The diluted hydrogen gas generator of Patent Document 1 described above generates a search gas by mixing hydrogen gas, which is a diffusible gas, and nitrogen gas, which is an inert gas, but these hydrogen gas and nitrogen gas are mixed. There is also a problem that the whole equipment becomes larger by mixing in an external mixing tank, and the equipment becomes larger by providing two mass flow controllers for gas flow control, and the flow path becomes complicated. ing.

When performing a leak inspection, hydrogen gas and nitrogen gas are mixed in a mixing tank to generate a mixed gas, and this mixed gas is sent to the workpiece as a search gas to detect leaks. However, if the mixing ratio of hydrogen in the mixing tank is increased due to a malfunction of the mass flow controller or the like, safety will be reduced.
A large amount of mixed gas with a predetermined concentration is generated in the mixing tank, and the gas used for the leak inspection of each sample is supplied from this mixed gas. It is necessary to adjust again the concentration of the search gas remaining in.
Further, a search gas in which a diffusible gas and an inert gas are mixed is commercially available, but it is necessary to suppress an increase in cost with an increase in the amount used.

The present invention was developed in order to solve the conventional problems, and its purpose is to mix a diffusible gas and an inert gas in a short time by a small and simplified facility for leak inspection. Another object of the present invention is to provide a search gas mixing method capable of safely producing the search gas and performing leak inspection of a pressure device easily and efficiently.

In order to achieve the above object, the invention according to claim 1 is a method for inspecting a sample such as a valve using a search gas composed of a diffusible gas and an inert gas, wherein one of the gases has a predetermined concentration. After mixing the sample gas with the pressure according to the above, the other gas is used to increase the pressure inside the sample up to the inspection pressure, so that the leak gas of the pressure equipment can be inspected with the search gas of the specified concentration. Is the way.

The invention according to claim 2 is a search gas in which a pressure ratio between a diffusible gas and an inert gas is 2.5:97.5 to 5.5:94.5, and the test gas is enclosed in the sample. It is a method of mixing.

The invention according to claim 3 is a search gas mixing method, wherein the diffusible gas is hydrogen gas and the inert gas is nitrogen gas.

The invention according to claim 4 is a method for mixing a search gas, which is filled with nitrogen gas and then pressurized to a test pressure with hydrogen gas.

The invention according to claim 5 is a method of mixing search gas in which hydrogen gas is charged and then pressurized to a test pressure with nitrogen gas.

According to the invention of claim 1, one of the diffusible gas and the inert gas is sealed in the sample at a pressure corresponding to a predetermined concentration, and then the other gas is filled up to the inspection pressure in the sample. By boosting the pressure, there is no need for tanks for gas mixing, gas flow rate control, and equipment, and the entire facility can be made smaller and simpler, and this facility can safely generate search gas for leak inspection. Highly accurate leak inspection of pressure equipment such as valves by search gas. As described above, by only controlling the pressure, it is possible to easily and efficiently detect the leakage of the sample by the predetermined concentration and the inspection pressure, and it is possible to suppress the cost required for the search gas manufacturing facility. Since a minimum amount of search gas required for leak inspection can be generated for each sample, wasteful search gas can be prevented from being generated and post-processing after the leak inspection can be quickly performed.

According to the invention of claim 2, the pressure ratio of the diffusible gas and the inert gas is sealed in the sample at a pressure ratio of 2.5:97.5 to 5.5:94.5. As a result, the search gas can be generated as a noncombustible high-pressure gas, and the safety of the search gas can be improved, and the accuracy of detection of the search gas by the sensor can be improved to reliably detect the leak.

According to the invention of claim 3, hydrogen gas is used as the diffusible gas, so that it is easier to obtain than other diffusible gases, and exhibits high diffusivity to be easily detected by the sensor. By using nitrogen gas as the inert gas, this nitrogen gas is mixed with hydrogen to generate a search gas at a low cost, and the chemical reactivity of the search gas after generation is kept low to improve safety and diffusion. It is possible to generate search gas with high utility value while maintaining the property.

According to the invention of claim 4, after the nitrogen gas, which is an inert gas, is filled in the sample, hydrogen gas is added to the atmosphere of the inert state to raise the pressure to the inspection pressure, thereby safely leaking. An inspection can be done.

According to the invention of claim 5, when the hydrogen gas accumulated in the cylinder is used, this hydrogen gas can be finely supplied for each sample, so that the hydrogen gas in the cylinder is used to the maximum without being wasted. You can do it. As a result, the running cost for generating the search gas can be reduced.

It is a circuit diagram which shows the initial state of the inspection line of the leak inspection equipment of a sample. FIG. 1A is a circuit diagram of an inspection line showing a state where nitrogen is pressurized in FIG. 1. (B) is a circuit diagram of an inspection line showing a state in which hydrogen is pressurized to (a). (A) is a circuit diagram of an inspection line showing a state of detecting external leakage of gas. (B) is a circuit diagram of an inspection line showing a state of purging residual hydrogen in the circuit. (A) is a circuit diagram of an inspection line showing a state in which air is exhausted from the sample. (B) is a circuit diagram of an inspection line showing a processing state after (a). (A) is sectional drawing which shows the chamber of a test sample. (B) is a partially cutaway front view showing a test sample. It is a graph which shows the behavior of the sensor to search gas. It is a schematic diagram which shows an example of a withstand voltage inspection apparatus. It is a longitudinal cross-sectional view showing a sample. (A) is a longitudinal sectional view of the cloth. (B) is a longitudinal sectional view of the tee. (C) is a longitudinal sectional view of the elbow. It is a flowchart of a withstand voltage inspection method. It is a partially-omitted schematic diagram which shows the inspection process by the withstand voltage inspection apparatus of FIG. It is a partially-omitted schematic front view which shows the inspection process by the withstand voltage inspection apparatus of FIG. It is a graph showing the voltage transition of the sensor. It is a schematic diagram which showed the other example of the withstand voltage inspection apparatus.

The search gas mixing method and the operation thereof according to the present invention will be described below in detail based on the embodiments.
The search gas mixing method of the present invention is an inspection method for a sample such as a valve using a search gas composed of a diffusible gas and an inert gas. When inspecting a sample, first, one gas is sealed in the sample at a pressure according to the specified concentration, and then the other gas is used to increase the pressure inside the sample to the inspection pressure to search for the specified concentration. It is designed to check the leak of pressure equipment with gas.

In this case, it is desirable to fill the sample with a pressure ratio of the diffusible gas and the inert gas at a pressure ratio of 2.5:97.5 to 5.5:94.5. When hydrogen gas is used as the diffusible gas, it is desirable to set the concentration of this hydrogen gas to 5%±0.5%, that is, 4.5 to 5.5%. The nitrogen gas and nitrogen gas are enclosed in the sample at a pressure ratio of 4.5:95.5 to 5.5:94.5.

The diffusible gas may be hydrogen gas, the inert gas may be nitrogen gas, and the diffusible gas may be a gas other than hydrogen gas as long as it has a property of having a small specific gravity and diffusing, for example, Various gases such as helium gas and methane gas can be used. When helium gas is used as the search gas, it has a high diffusivity like a mixed gas containing hydrogen. As the inert gas, a gas other than nitrogen gas may be used as long as it is a gas having low reactivity and inertness.

When mixing the search gas, it is advisable to fill the nitrogen gas and then increase the pressure up to the inspection pressure with hydrogen gas.
Alternatively, after filling the hydrogen gas, the pressure may be increased to the inspection pressure with nitrogen gas.

Subsequently, FIG. 1 shows an example of a circuit diagram of an inspection line 11 of a leakage inspection equipment 10 for performing a leakage inspection of the sample 1 by the search gas mixing method of the present invention. A method of mixing the search gas according to 10 will be described.

1 shows an initial state of the inspection line 11, and FIGS. 2 to 4 show circuit diagrams of respective steps when the search gas is generated by the inspection line 11 of FIG. In the figure, the solid line shows the open state of the flow path (circuit) of the inspection line 11, and shows the state in which gas can flow inside. On the other hand, the alternate long and two short dashes line shows the closed state of the flow path, and represents the state in which the gas does not flow inside.

In the inspection line 11, the first flow path 20 is a flow path for supplying nitrogen gas, and in this first flow path 20, a nitrogen gas supply source 21, a first regulator 22, and a first solenoid valve 23 are provided from the primary side. It will be established continuously. The second flow passage 30 is a flow passage for supplying hydrogen gas, and the hydrogen gas supply source 31, the second regulator 32, and the second electromagnetic valve 33 are continuously provided in the second flow passage 30 from the primary side. The third flow passage 40 is a flow passage for supplying compressed air, and an air supply source 41 and a third electromagnetic valve 42 are continuously provided in the third flow passage 40 from the primary side.

In this embodiment, a commercially available 100% nitrogen gas cylinder is used as the nitrogen gas supply source 21, a commercially available 100% hydrogen gas cylinder is used as the hydrogen gas supply source 31, and an air compressor is used as the air supply source 41.

The above-mentioned first flow path 20, second flow path 30, and third flow path 40 are connected so as to join the sample 1 at the primary-side flow path 50, and the nitrogen gas from the nitrogen gas supply source 21 Either the hydrogen gas from the hydrogen gas supply source 31 or the compressed air from the air supply source 41 is switched by the first solenoid valve 23, the second solenoid valve 33, and the third solenoid valve 42 to switch the flow passage on the primary side flow passage. It is possible to flow from 50 to DUT 1. The solenoid valves include fourth to sixth solenoid valves, which will be described later, in addition to the first, second and

third solenoid valves

23, 33 and 42. The solenoid valves of these first to sixth solenoid valves are provided. The entire flow path (circuit) can be opened/closed by the opening/closing control.

The first regulator 22 is provided so that the nitrogen gas from the nitrogen gas supply source 21 can be adjusted, and the second regulator 32 is provided so that the pressure of the hydrogen gas from the hydrogen gas supply source 31 can be adjusted. After adjusting the hydrogen gas to a pressure of 1.0 MPa by the second regulator 32 at 95 MPa, it is sent to the first electromagnetic valve 23 side and the second electromagnetic valve 33 side, respectively.

The primary side flow path 50 is provided so as to be connectable to the upstream side opening 1a of the sample (valve) 1 which is detachably mounted in the chamber 51 which is a housing part of the sample 1, A secondary side flow passage 52 is provided so as to be connectable to the downstream side opening portion 1b of the first unit 1. A branch passage 53 is provided in the primary passage 50, and the branch passage 53 is connected to an exhaust unit (exhaust port) 55 capable of exhausting to the outside via a fourth electromagnetic valve 54.

The secondary passage 52 is connected to the exhaust unit 55 via a pressure sensor 56 and a fifth solenoid valve 57. The pressure sensor 56 can detect the pressure value inside the DUT 1, and the pressure sensor 56 measures the pressure, and the pressure of hydrogen gas or nitrogen gas can be adjusted by the regulator described above.

The third flow path 40 is provided with an air supply path 60 that branches from before the third electromagnetic valve 42 and is connected to the chamber 51. The air supply path 60 branches in the middle and is provided at two locations of the chamber 51. The air from the air supply source 41 can be supplied into the chamber 51 and the fluid in the chamber 51 can be exhausted through the air supply path 60.
The air supply path 60 is provided with a sixth electromagnetic valve 61 and a vacuum part 62 capable of sucking air in the chamber 51. The vacuum part 62 has an exhaust part (exhaust port) 63 capable of discharging the sucked gas to the outside. It is connected.

The chamber 51 is provided inside with a volume large enough to accommodate the sample 1, and a sensor 70 for detecting gas leaking from the sample 1 is attached to the chamber 51. The chamber 51 has an inspection space having a space in which the search gas supplied to the DUT 1 can diffuse, and the inspection space is isolated from the outside. The inspection space does not necessarily have to be sealed, and may be provided in a semi-sealed state as long as the gas leaked from the sample 1 can be detected by the sensor 70. Regardless of whether the chamber 51 is in a closed state or a semi-closed state, the inspection volume is preferably as small as possible in order to make it easier to detect the leaked gas from the sample 1.

The sensor 70 is composed of a hydrogen gas sensor capable of detecting hydrogen gas, which makes it possible to reliably detect hydrogen in a mixed gas of hydrogen and nitrogen, which is a diffusible gas leaked from the sample 1. There is. The sensor 70 is mounted at a position where hydrogen can be detected in the chamber 51 by an arbitrary number, but may be mounted movably so that the position can be adjusted. When helium gas is used as the search gas, a gas heat conduction type sensor may be used as the sensor.

The sensor 70 is composed of a module that outputs a voltage according to the concentration of leaked hydrogen when a predetermined voltage is applied. Before the leak inspection, it is advisable to change the output voltage by the resistance adjusting volume and finely adjust the sensitivity according to the warm-up state of the sensor 70 and the change of the hydrogen concentration in the atmosphere.

As the sensor 70, a commercially available semiconductor sensor that can output an analog signal (0-5V) is used, and for example, a hot wire semiconductor hydrogen sensor is used. The hydrogen sensor 70 is a sensor that utilizes a change in electric conductivity due to adsorption of hydrogen gas on the surface of a metal oxide semiconductor such as stannic oxide (SnO ₂ ). In this case, the output voltage becomes logarithmic with respect to the gas concentration, and high-sensitivity output is possible even at low concentration.

Although not shown, a control unit including a CPU (central processing unit) is connected to the inspection line 11, and the control unit includes a sensor 70,

electromagnetic valves

23, 33, 42, 54, 57, 61, and regulators 22. , 32, nitrogen gas supply source 21, hydrogen gas supply source 31, air supply source 41, etc. are electrically connected. The control section stores a table (installation data) set based on the nominal pressure, nominal diameter, valve type, etc. of the sample 1, and the operation of each section is controlled based on this table.

The control unit is equipped with a digital display unit, and when hydrogen leaks from the DUT, it outputs to this digital display unit as a voltage according to the hydrogen gas concentration via the signal processing unit provided in the control unit. To be done. The digital display unit has an LCD (liquid crystal display), and the output voltage of each sensor 70 is displayed as an indicator on this LCD.

Specimen 1 is composed of piping parts such as valves and pipe fittings, and a ball valve is used in this example. The sample (ball valve) has a nominal diameter of 1/2 to 2 inches, and the inspected volume for pressure resistance inspection is about 12 to 236 mL. The sample 1 may be other than the ball valve, and may be, for example, various valves such as a gate valve, or a housing of a pneumatic actuator (not shown) used for opening and closing the ball valve. In this case, the volume to be inspected for the pressure resistance inspection of the housing is about 150 to 610 mL. Thus, the volume of the sample to be mounted in the chamber 51 is preferably less than 1000 mL, for example. The sample 1 including the ball valve of this example is connected between the primary side flow passage 50 and the secondary side flow passage 52 by a joint having appropriate pressure resistance.

Next, a method of mixing the search gas by the above-described leak inspection facility 10 and a leak inspection method of the sample 1 will be described.
FIG. 1 shows an initial state when performing a leak test with a search gas. In this case, the first, second, third

electromagnetic valves

23, 33, 42, and the sixth electromagnetic valve 61 are closed, and the first, second,

third flow paths

20, 30, 40, and the air supply path 60 are connected. The flow path of is blocked. From this state, the nitrogen gas from the nitrogen gas supply source 21 is controlled by the first regulator 22 and the pressure of the hydrogen gas from the hydrogen gas supply source 31 is controlled by the second regulator 32, respectively, so that each gas having a predetermined pressure is supplied. There is. In FIG. 1, the ball valve as the sample 1 is in a fully closed state, and before pressurization in FIG. 2, the ball valve 1 is in a half-opened state. The search gas leak inspection shown in FIG. 3 is performed in this half-opened state.

At that time, by adjusting the

regulators

22 and 32 so that the pressure of the nitrogen gas is 0.95 MPa and the pressure of the hydrogen gas is 1.00 MPa, the pressure ratio between the hydrogen gas and the nitrogen gas after pressurization is adjusted. The ratio is 5:95, and the hydrogen-nitrogen mixed gas having a pressure of 1.0 Ma is mixed inside the sample 1 according to the ratio of the pressure ratio, and the pressure resistance leak test is performed at this pressure value. At this time, the fourth solenoid valve 54 and the fifth solenoid valve 57 are maintained in the open state. In the following description, the open/closed state is maintained unless each solenoid valve is operated.

2(a) shows a state in which the inside of the sample 1 is pressurized with nitrogen gas. At this time, the first solenoid valve 23 is opened and the fourth solenoid valve 54 and the fifth solenoid valve 57 are closed. At that time, the first flow path 20, the primary-side flow path 50, and the secondary-side flow path 52 communicate with each other. In this way, the sample 1 is first pressurized with nitrogen gas, and the pressure is increased to 0.95 MPa described above. In this case, in addition to adjusting the pressure of the nitrogen gas by the first regulator 22, the pressure is also confirmed by the pressure sensor 56, and the measured value of the pressure is measured by the pressure sensor 56 in this way to obtain the gas with the accurate pressure. Supply is possible. By pressurizing with nitrogen gas first, a safe leak inspection work is possible.

FIG. 2B shows a state in which the inside of the sample 1 is continuously pressurized with hydrogen gas. In this case, the first solenoid valve 23 is closed and the second solenoid valve 33 is opened. As a result, hydrogen gas is supplied from the second flow path 30 to pressurize the sample 1 while the supply of nitrogen gas from the first flow path 20 is stopped. The pressure of the hydrogen gas at this time is 1.00 MPa described above, and the pressure of the hydrogen gas is raised to 1.0 MPa in a state where the hydrogen gas and the nitrogen gas are mixed. As a result, a mixed gas of about 5% hydrogen is formed in the sample 1 with the ratio of hydrogen gas and nitrogen gas being 5:95 as described above, and the search gas of this predetermined concentration is used as a pressure device. Perform a leak inspection of sample 1.

FIG. 3A shows a state in which the second electromagnetic valve 33 is closed, and in this state, the sensor 70 set in the chamber 51 detects the leak of the search gas from the sample 1. At this time, the search gas leaked from the sample 1 is accurately detected by the sensor 70 in a state where the chamber 51 prevents the diffusion of the search gas to the surroundings. According to the measurement result of the leak inspection, it becomes possible to judge the pass/fail of the sample 1 as a product.

Fig. 3(b) shows a state in which residual hydrogen in the circuit is purged with air after performing a leak test. In this case, the fourth solenoid valve 54 and the fifth solenoid valve 57 are opened to exhaust from the exhaust unit 55, and then the fourth solenoid valve 54 is closed to the third solenoid valve 42 and the fifth solenoid valve 57. Are opened, so that the third flow path 40 communicates with the exhaust part 55 of the secondary flow path 52 through the primary flow path 50. As a result, the residual hydrogen in the circuit including the inside of the DUT 1 is discharged from the exhaust unit 55 by air.

FIG. 4A shows a state in which the third solenoid valve 42 is operated in the open state, and then the DUT 1 is operated in the valve open state by the drive device (not shown). As a result, the DUT 1 can be disconnected from the circuit and the internal pressure can be exhausted.

FIG. 4B shows a state in which the upstream side opening 1a and the downstream side opening 1b of the sample 1 are removed from the primary side flow path 50 and the secondary side flow path 52, respectively, and unclamped from the circuit. There is. In this state, the sixth solenoid valve 61 is operated to open so that the third flow passage 40 and the air supply passage 60 are communicated with each other, thereby purging the chamber 51 with air through the air supply passage 60. The residual hydrogen in the air supply path 60 is vacuumed by the vacuum section 62, and the vacuumed residual hydrogen is discharged from the exhaust section 63. After passing through the above steps, the leak inspection of one sample 1 is completed, and the inspection line 11 of the leak inspection facility 10 is continuously set to the initial state of FIG. 1 to perform the leak inspection of another sample 1. It will be possible to do.

In the above-described embodiment of the search gas mixing method of the present invention, the first regulator 22 and the first solenoid valve 23 are provided in the first flow passage 20 and the second regulator 32 is provided in the second flow passage 30 in the inspection line 11 of the leak inspection equipment 10. Since the second solenoid valve 33 is provided, the first regulator 22 sets the nitrogen gas from the nitrogen gas supply source 21 to 0.95 MPa, and the second regulator 32 sets the hydrogen gas from the hydrogen gas supply source 31 to 1.00 MPa. It is possible to regulate the pressure and supply each gas of these predetermined pressures into the test valve 1 with high accuracy by opening/closing the first solenoid valve 23 and the second solenoid valve 33.

As a result, after nitrogen gas of 0.95 MPa is filled in the sample 1, hydrogen gas can be supplied to accurately increase the pressure to 1.0 Ma, which is a predetermined inspection pressure. A 5% mixed gas having a concentration of 5:95 can be provided as a leak inspection search gas, and this search gas can be used as a leak inspection gas for the sample 1. As described above, since a search gas having a concentration of about 5% that is safe and suitable for detection can be provided in the sample 1, there is no need to provide a tank or equipment for mixing the search gas outside, and the entire leak inspection facility 10 can be provided. It is possible to carry out an accurate leak inspection in a short time while achieving a compact size.

On the other hand, by adjusting the

regulators

22 and 32 such that the pressure of hydrogen gas is 0.05 MPa and the pressure of nitrogen gas is 1.0 MPa, the pressure ratio of the hydrogen gas and the nitrogen gas after pressurization is 5%. It is also possible that the hydrogen-nitrogen mixed gas having a pressure of 1.0 MPa is mixed inside the test sample 1 according to this mixing ratio, and the pressure resistance leak test is performed at this pressure value.
As a result, the hydrogen gas in the cylinder can be used up to 0.05 MPa, and the hydrogen gas in the cylinder can be used up to the maximum without being wasted.

Next, a simulation experiment was conducted using the test sample. FIG. 5B shows an experimental sample (experimental jig) 80. The experimental sample 80 is made by imitating a ball valve having a nominal diameter of 2 inches. Was formed into a substantially cylindrical shape. Regarding the dimensions of the hollow portion 81 inside the test sample 80, the inner diameter φd was 50 mm and the length was 120 mm.

FIG. 5A shows a chamber 82 for accommodating the experimental sample 80 in a state of being clamped by the clamp jigs 90 and 91, and the axial length of the chamber 82 is the experimental sample. It is formed slightly longer than the length of the sample. Gas sensors 83 are provided at six places in the chamber 82, and the gas leaked from the test sample 80 can be detected by these gas sensors 83. In the figure, the search gas was made to flow from the “front” clamp jig 90 side toward the “rear” clamp jig 91 side.

The experimental sample 80 was stored in the chamber 82, and this was connected to the inspection line of the leakage inspection equipment to measure the amount of leakage. At this time, three types of search gases were supplied to the sample, and the behavior of the gas sensor 83 was measured through a constant flow rate device with a leak rate of 0.3 mL/min. In this case, the initial voltage output from the gas sensor 83 is set to 2.0V, and when the initial voltage reaches 105%, that is, when the voltage rises from 2.0V to 2.1V or more, a gas leak is detected. I decided to do it.

The three types of search gas were (1) a commercially available mixed gas, and (2) and (3) a gas mixed in a local leak inspection facility by the search gas mixing method of the present invention. (1) As a commercially available mixed gas, a mixed gas containing 5% hydrogen and 95% nitrogen was used. As the on-site mixed gas of (2), after supplying nitrogen gas 1.14 MPa into the experimental sample 80, hydrogen gas is supplied to set the pressure in the experimental sample 80 to 1.20 MPa, that is, hydrogen gas. The pressure ratio of nitrogen gas to nitrogen gas was set to 5:95, so that a mixed gas of about 5% hydrogen and about 95% nitrogen was provided in the experimental sample 80. As the on-site mixed gas of (3), after supplying nitrogen gas of 1.17 MPa into the experimental sample 80, hydrogen gas is supplied so that the pressure inside the experimental sample 80 is 1.20 MPa, that is, hydrogen gas. The pressure ratio of nitrogen gas to nitrogen gas was 2.5:97.5, so that a mixed gas of approximately 2.5% hydrogen and approximately 97.5% nitrogen was provided in the experimental sample 80.

The gas sensor 83 is used for the pseudo-leakage (0.3 mL/min) generated through the constant flow rate device by pressurizing the inside of the experimental sample 80 with the above three kinds of search gases (1) to (3). The graphs in FIG. 6 show how each of these reacts.

In FIG. 6, comparing the commercially available mixed gas of (1) with the on-site mixed gas of (2), the voltage of the gas sensor 83 both rises approximately 15 seconds after the start of the inspection. From this, it can be said that the on-site mixed gas of (2) can be subjected to a leak test in a state close to the commercially available mixed gas of (1) by pressure control.

On the other hand, regarding the on-site mixed gas of (3), a voltage increase was confirmed by the gas sensor 83 approximately 20 seconds after the start of the inspection, and a leak was detected. From this, it can be said that even if the concentration of hydrogen gas is about 4.5%, it can be said that the safe inspection can be completed within a predetermined time (for example, within the cycle time of the processing process which is a pre-process of the leak inspection). ..
From these, it can be said that the mixed gas prepared by the search gas mixing method of the present invention can be sufficiently used as a substitute for a commercially available mixed gas.
In that case, the concentration of the mixed search gas (hydrogen gas) can also be controlled by controlling the pressure of each gas. It was confirmed that even a low-concentration search gas can be detected, so even if the hydrogen gas concentration is lowered in consideration of safety, it can be used as a search gas for a pressure test or a leak test.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the description of the embodiments, and does not depart from the spirit of the invention described in the claims of the present invention. Therefore, various changes can be made. For example, the present invention can be applied as a search gas for inspecting a valve seat such as a ball valve or a globe valve. Specifically, in the case of the ball valve according to the embodiment, in FIG. 9A, after performing an external leakage inspection of the search gas from the ball valve within a predetermined inspection time, that is, a pressure resistance inspection, Prior to the air purging in (1), the ball valve is fully closed and the search gas is sealed in the cavity of the valve, so that it can be applied to the leak inspection from the valve seat within a predetermined inspection time. To detect the search gas in the valve seat inspection, a flow sensor (not shown) connected to the primary side flow passage 50 or the secondary side flow passage 52 is used.
Further, the present invention can be applied as a search gas for valves other than ball valves such as globe valves and gate valves, and can perform pressure resistance inspection of various pressure devices such as housings of pneumatic actuators, including piping devices other than valves. It can be applied to leak inspection.

Next, as an example of a specific example of the search gas mixing method of the present invention, a case of applying it to a pressure resistance inspection device will be described.

For example, since piping components such as fittings are required to have high pressure resistance, a pressure resistance inspection using a search gas is carried out before shipment to confirm strength and leakage.
In this case, when a pressure test is performed on a work (test sample) such as a piping component, a test called a pressure change method may be performed. In the pressure resistance test using the pressure change method, prepare a leak-free standard product (master), pressurize the work and master simultaneously, and use the differential pressure sensor to determine the pressure change in the work due to leakage Leakage is detected by detecting the difference as a change.

On the other hand, as a pressure resistance test other than the pressure change method, a pressure resistance test may be performed by detecting leakage of fluid from the inside of the work to the outside. In this case, it is known that air may be used as a search fluid in a pressure resistance test of a valve having a small nominal diameter (for example, a nominal diameter of 50 A or less). As a pressure resistance test by detecting such gas leakage, For example, a hydrogen leak test may be used. In this case, hydrogen/nitrogen mixed gas is applied to the work, and the leak is judged by detecting the leak of gas to the outside with a gas sensor.
As a device for performing such a test by detecting a fluid leak to the outside, for example, Japanese Patent Laid-Open No. 62-55538 (hereinafter referred to as "reference 1") discloses a submersible pressure leak inspection device. This leak inspection device is designed to inspect a work for pressure leak by filling a work to be inspected with a fluid having a predetermined pressure and observing the presence or absence of bubbles in the work in a state of being submerged in a water tank. ing.

As a technique for pressure resistance inspection of piping parts with a submersion type leak inspection device, for example, Kojima Seisakusho Co., Ltd. (HP author unknown), "100% inspection submerged joint leak inspection", [online], October 31, 2000 , Kojima Seisakusho Co., Ltd. [Search on December 11, 2018], Internet <URL:http://kojima-core.co.jp/20001031report.html> (hereinafter referred to as "Reference 2") submersion ceremony Joint leak testing is disclosed. In this leak inspection, a joint, which is a piping component, is sunk into a water tank as a work, air pressure is applied, and the joint is visually inspected to confirm the leak location when a leak occurs.

When performing pressure resistance inspection of a work (test sample) by the pressure change method described above, if the volume of this work is large or the inspection pressure is high, the time at the stage of adjusting to the same pressure as the reference product before starting leak measurement In some cases, leakage may not be detected because it becomes necessary or the differential pressure becomes difficult to stabilize.

On the other hand, in the case of detecting the leakage of gas from the work submerged in water to the outside as in Reference 1 and Reference 2, the operator visually confirms whether bubbles are generated from the work. The work takes time, and it is difficult to make the inspection time constant for each work, and the work time tends to be uneven. Since the visual inspection imposes a heavy burden on the operator, if the inspection work is carried out continuously, it will take more time due to accumulation of fatigue.
Furthermore, it takes time to move up and down when the work is submerged in the water tank, and further time is required when the water drops of the work wet with water are wiped off or dried after the inspection. Since water is used for confirming gas leaks, there is a problem that facilities for wastewater treatment are required and post-treatment is time-consuming, and reduction in environmental load is also required.
For these reasons, it has been earnestly desired to develop a high-accuracy and simple withstand voltage inspection device that can shorten the withstand voltage inspection time and facilitate the detection work.

In order to solve the above problems, in the specific example of the withstand voltage inspection apparatus shown below, the withstand pressure inspection using a search gas capable of continuously and quickly performing the withstand pressure inspection of the sample under a short time and capable of easily and accurately detecting the leak is provided. A device is provided.

This specific example is a pressure resistance inspection device 101 using a search gas such as hydrogen, and includes an opening/closing plate 111 for opening and closing the inspection space S, a sensor 112 attached to the opening/closing plate 111 for detecting the search gas, and a sensor 112 for detecting the search gas. The DUT 102 in which the sensor 112 is arranged in the inspection space S is brought close to or provided with a proximity withdrawal means for withdrawing the opening/closing plate 111 from the inspection space S after the inspection is completed. As a result, the withstand voltage inspection device 101 uses the search gas in which the influence of the search gas leaked when the sample 102 is unclamped is reduced.

In this specific example, the proximity withdrawing means 113 is a rotating mechanism using a servomotor 130 or the like, and in the withstand voltage inspection device 101 using a search gas, the opening/closing plate 111 is withdrawn from the inspection space S by this rotating mechanism. is there.

Further, the proximity retraction means 151 is a slide mechanism that uses a cylinder 152 and the like, and is a pressure resistance inspection device 150 that uses search gas to retract the opening/closing plate 153 from the inspection space S by this slide mechanism.

Further, another aspect of this specific example is a pressure resistance inspection method using a search gas such as hydrogen, in which the inspection space S is opened and closed by the opening/closing plate 111 and the sample 102 is arranged in the inspection space S. The search gas is detected while the sensor 112 attached to the opening/closing plate 111 is brought close to the DUT 102 by the proximity retreating means, and after the inspection by the search gas is completed, the opening/closing plate 111 is removed from the inspection space S by the proximity retreating means. This is a withstand voltage inspection method using a search gas in which the influence of the search gas leaked when the sample 102 is unclamped is reduced by evacuating the sensor 112 and exposing the sensor 112 to the outside air.

Further, even after the inspection is completed, the sensor 112 is kept in the measuring state, and when hydrogen remains above a predetermined level, the gas diffusion means such as the fan 140 is used to perform forced intake or forced exhaust in the vicinity of the sensor 112. This is a withstand voltage inspection method using a search gas that reduces the influence of the search gas leaked during the unclamping of the sample 102 and allows the next sample 102 to be inspected early.

As an effect of this specific example, after the withstand voltage inspection is completed, the opening/closing plate 111 is retracted from the inspection space S by the proximity retraction means 113, the sensor 112 is exposed to the outside air, and the influence of the search gas leaked when the sample 102 is unclamped is influenced. By reducing the amount, the search gas around the sensor 112 can be removed after the inspection is completed, and the influence of the search gas remaining in the inspection space S can be suppressed early to shorten the processing time after the breakdown voltage inspection. Therefore, the time required for the withstand voltage inspection of each sample 102 can be shortened, and the next sample 102 can be set in a state capable of withstanding voltage inspection to continuously and quickly inspect the sample 102. In addition, since the sensor 112 is brought into proximity to the sample 102 by the proximity retracting means 113 in the state where the sample 102 is arranged in the inspection space S, it is possible to easily open and close by using this one proximity retracting means 113. The plate 111 can be brought close to or retracted from the DUT 102, and the sensor 112 attached to the opening/closing plate 111 can be arranged at a predetermined position of the DUT 102 to accurately detect a leak.
There is little influence due to the size of the sample product and the high or low of the inspection pressure, the above-mentioned functions are stably exhibited, and in addition to the piping parts such as the joints, the sample 102 of all aspects can be quickly subjected to the pressure resistance test. Can be implemented.
Since the search gas is used as the inspection fluid, post-treatment is easy and the load on the environment is small.

Further, the proximity retracting means 113 is a rotating mechanism using the servo motor 130 and the like, and the opening/closing plate 111 is retracted from the inspection space S by this rotating mechanism. The sensor 112 is less susceptible to the influence of the search gas in the inspection space S because the opening/closing plate 111 is rotated in a direction away from the inspection space S to be in an open state by making contact with the.

Further, the proximity retracting means 151 is a slide mechanism using a cylinder 152 or the like, and since the opening/closing plate 153 is retracted from the inspection space S by this sliding mechanism, the sensor 112 can be quickly moved to the atmosphere when the opening/closing plate 153 is retracted. The influence of the search gas can be reduced early by contacting the. Since the open/close plate 153 slides in the direction away from the inspection space S to be in the open state, the sensor 112 is less likely to be affected by the search gas in the inspection space S, and further, the slide amount of the open/close plate 153 is increased to perform the inspection. By increasing the distance of the sensor 112 from the space S, the influence of the search gas on the sensor 112 can be further suppressed.

After the inspection, the influence of the search gas remaining near the sensor 112 can be reduced early to shorten the processing time after the breakdown voltage inspection. Therefore, the time required for the withstand voltage inspection of each sample 102 can be shortened, and the sample 102 can be inspected continuously in a short time in a state where the next sample 102 can be quickly subjected to the withstand voltage inspection. Moreover, the opening/closing plate can be easily brought close to or retracted from the DUT by one proximity retreat means, and the sensor 112 attached to the opening/closing plate can be arranged at a predetermined position of the DUT 102 to accurately detect the leak. Become.
There is little influence due to the size of the sample 102 and the high or low of the inspection pressure, the above-mentioned functions are stably exhibited, and in addition to the piping parts such as the joints, the sample 102 of all modes can be quickly pressure-resistant. Inspection can be carried out.

By forcibly inhaling or forcibly exhausting the vicinity of the sensor 112 with the gas diffusion means such as the fan 140, the search gas staying after the pressure resistance test can be quickly removed, and the influence of the search gas leaked at the time of unclamping can be reduced. By performing the inspection of the sample 102 early, the withstand voltage inspection of the sample 102 can be continuously performed in a short time.

FIG. 7 shows an example of a withstand voltage inspection apparatus (hereinafter referred to as an apparatus main body 101) for performing a withstand voltage inspection by the search gas mixing method of the present invention, and in FIG. 8, a sample to be inspected by the apparatus main body 101. (Work) 102 is shown. FIG. 9 shows a flowchart in this example of the withstand voltage inspection method using the search gas.

The apparatus main body 101 in this example is installed at the position of the chamber 51 in the leak inspection equipment 10 of FIG. 1 described above, and the device main body 101 enables the sample 102 to be subjected to pressure resistance inspection.

The sample 102 to be pressure-tested by the apparatus main body 101 is composed of, for example, pipe parts such as a pipe joint and a valve. In this example, an integrally molded screw-in type having a female screw on the flow path opening side as a pipe end connection part. Pipe fittings are used. As the pipe joint (test sample) 102, there are a cross shown in FIG. 8A, a tee shown in FIG. 8B, an elbow shown in FIG. 8C, and the like. However, pipe fittings in which the central axes of all the branch flow paths 103 are arranged substantially on the same plane are suitable, which intersect each other at intervals of 90°. Female screws 105 are formed on the inner peripheral sides of the open end surfaces 104 of the cloth, tee, and elbow, respectively. The pipe joint to be inspected has, for example, a nominal diameter of 1/8 inch to 4 inches, and although not shown, it is also possible to perform pressure resistance inspection of a straight pipe joint sample.

The apparatus main body 101 of FIG. 7 is a pressure resistance inspection apparatus that uses a search gas such as hydrogen, and includes a mounting jig 110, an opening/closing plate 111, a sensor 112, and a proximity retreat means 113.
The mounting jig 110 is provided on the apparatus main body 101 to clamp the DUT 102 so as to perform pressure resistance inspection, and includes a frame body 120, a fixed side jig 121, a movable side jig 122, and a cylinder mechanism 123. ..

The frame 120 is in the shape of a rectangular parallelepiped, and the inside of the frame 120 is hollowed out to form a concave housing portion 120a. A fixed-side jig 121, a movable-side jig 122, and a cylinder mechanism 123 are housed in the housing portion 120a, and an inspection space S for pressure resistance inspection of the sample 102 is provided.

The inspection space S has a volume capable of accommodating the DUT 102, and has a size capable of diffusing the search gas supplied to the DUT 102 and leaked out, and is provided with a small volume in which this gas can be easily detected. To be The inspection space S is provided so as to be isolated from the outside by the opening/closing plate 111. In this case, if the leaked gas can be detected, it can be provided in a closed state or a semi-closed state.

The opening/closing plate 111 is provided by a transparent, semi-transparent, or opaque acrylic plate, and one end side thereof is attached to the movable side jig 122 as a rotating shaft (not shown). It is rotatable. By rotating the opening/closing plate 111, the region of the inspection space S can be opened/closed. When the opening/closing plate 111 shown in FIGS. 10(a) and 10(e) is fully opened, the opening/closing plate 111 becomes substantially horizontal. On the other hand, when the opening/closing plate 111 shown in FIG. 10D is fully closed, the inspection space S can be closed to be isolated from the outside.

The sensors 112 are arranged in the vicinity of four clamp parts described later, and the four sensors 112 can detect the leak of the search gas corresponding to the four branch flow paths 103 when the DUT 102 is a cross. Further, when the DUT 102 is a tee or an elbow, the DUT 102 is placed at an appropriate position. In FIG. 7, a through hole 124 is provided at a sensor mounting position of the opening/closing plate 111, and a gas detection unit 125 provided in the sensor 112 when the opening/closing plate 111 is fully closed is provided in the inspection space S with respect to the through hole 124. When facing, the sensor 112 is mounted so as to be flush with the surface of the opening/closing plate 111 on the inspection space S side. This makes it easier for the gas detection unit 125 to detect the leaked gas near the inspection space S, and when the opening/closing plate 111 opens, the gas detection unit 125 causes the inspection space to increase as the opening degree increases. It is designed to move away from S.

As the search gas detected by the sensor 112, for example, a mixed gas of nitrogen gas which is an inert gas and hydrogen gas having diffusivity is used, and 5% hydrogen in which the ratio of the nitrogen gas and the hydrogen gas is 95:5. Mixed gas is used.
Therefore, the sensor 112 is composed of a hydrogen gas sensor capable of detecting hydrogen gas, and the hydrogen gas sensor 112 detects hydrogen in a mixed gas of hydrogen and nitrogen, which is a diffusible gas leaked from the sample 102. It will be possible. The sensor 112 is attached at a position where hydrogen can be detected in the inspection space S by an arbitrary number of attachments.

The sensor 112 is composed of a module that outputs a voltage according to the concentration of leaked hydrogen when a predetermined voltage is applied. Before the breakdown voltage test, the output voltage may be changed by the resistance adjusting volume, and the sensitivity may be finely adjusted according to the warm-up state of the sensor 112 or the change of the hydrogen concentration in the atmosphere.

As the sensor 112, a commercially available semiconductor sensor that can output an analog signal (0-5V) is used, and for example, a hot wire semiconductor hydrogen sensor is used. The hydrogen sensor 112 is a sensor that utilizes a change in electrical conductivity due to adsorption of hydrogen gas on the surface of a metal oxide semiconductor such as stannic oxide (SnO ₂ ). In this case, the output voltage becomes logarithmic with respect to the gas concentration, and high-sensitivity output is possible even at low concentration.

The proximity retracting means 113 is a rotating mechanism using the servo motor 130, and is attached to the rotating shaft of the opening/closing plate 111 so that the opening/closing plate 111 can be opened/closed about the rotating shaft. From this fact, if the opening/closing plate 111 is operated in the closing direction by the proximity retreat means 113, the gas detection part 125 of the sensor 112 attached to the opening/closing plate 111 is brought close to the sample 102 arranged in the inspection space S, or By operating the opening/closing plate 111 in the opening direction after the inspection, the opening/closing plate 111 can be retracted from the inspection space S.
At this time, the opening/closing plate 111 is retracted from the inspection space S by the rotating mechanism 113, and the gas detection unit 125 is brought into contact with the outside air while the sensor 112 is separated from the inspection space S, whereby leakage occurs when the sample 102 is unclamped. The influence of the released search gas is reduced.

The fixed-side jig 121 is mounted in a fixed state in the frame 120, and after the sample 102 is placed on the fixed-side jig 121 in a predetermined state, it is provided by the movable-side jig 122. The withstand voltage test can be performed with the prototype 122 clamped. The fixed-side jig 121 includes two cylindrical

fixed clamp portions

131 and 131, and these fixed clamp portions 131 have a clamp surface 132 having a sealing property on the clamp side.

Each clamp surface 132 is provided in such a shape and at an interval that the open end surfaces 104, 104 of a pair of adjacent

branch flow channels

103, 103 of the sample 102 can be clamped in a sealed state. They are provided at intervals of 90° according to the angle of the branch channel 103. Although not shown, these fixed clamp parts 131 are provided with protrusions for supporting the sample 102 in a stable state.

Inside each of the fixed clamp portions 131, fluid flow paths (not shown) for flowing a fluid such as a search gas are formed so as to communicate with the connection side with the sample 102, respectively.

Connection parts

133 and 133 for external flow path connection are provided outside each fixed clamp part 131. In this example, the connection portion 133 on the right side of FIG. 7 is the pressurizing side by the search gas, and the connection portion 133 on the left side is the exhaust side, and the pressurizing side connecting portion 133 and the exhaust side connecting portion 133 have external flow paths (not shown), respectively. When connected, the search gas and compressed air can be flowed from the right side to the left side of the DUT 102.

On the other hand, the movable jig 122 is attached to a piston 134 provided in the cylinder mechanism 123, and is provided by the piston 134 so as to be capable of reciprocating in the vertical direction in FIG. 7. The movable-side jig 122 is provided with two cylindrical

movable clamp portions

135, 135, and these movable clamp portions 135 have sealing

surfaces

136, 136, which are sealingly sealed and have a sealing property. Both or one of the clamping surfaces 136 is brought into contact with the sample 102, and the sample mechanism 102 is pressed by the cylinder mechanism 123 in the direction of the fixed-side jig 121, whereby the sample 102 can be clamped.

As described above, the movable clamp part 135 can be provided in various structures as long as it can press the sample 102 in the direction of the fixed-side jig 121, but it is symmetrical to the fixed clamp part 131 as in this example. By providing it in a shape, the non-inspection side of the sample 102 can be fixed between the fixed clamp part 131 and the sample clamp 102 by pressing the non-inspection side with the movable clamp parts 135 at 90° intervals. Become. As a result, in addition to the case where the DUT 102 is the cloth shown in FIGS. 7 and 8A, the fixed side jig 121 is used even when the tee shown in FIG. 8B and the elbow shown in FIG. And the movable jig 122 are firmly held, and the two open end surfaces 104 of the sample 102 and the clamp surface 132 of the fixed clamp portion 131 can be fixed while securing the sealability. In this case, it is possible to replace the movable clamp portion 135 with a different shape according to the shape and size of the tee or elbow, and this makes it possible to handle tees and elbows of various shapes and sizes.

A search gas supply source and an exhaust flow path (not shown) are connected to the connection part 133, respectively, and the search gas is supplied from one connection part 133 side in the clamped state of the sample 102 to apply a predetermined pressure to the inside of the cloth 102. The pressure is checked by detecting the gas leaking into the inspection space S with the sensor 112, and then exhausted from the other connecting portion 133 side.

Although not shown, for example, if the fixed clamp part 131 and the movable clamp part 135 are formed in a rectangular shape and the volume thereof is larger than the inspection space S, the inspection space S increases as the volume of the

clamp parts

131 and 135 increases. Volume becomes relatively small. By narrowing the inspection space S in this way, the inspection time can be shortened.

The apparatus main body 101 may have a clamp structure different from the one described above, or an attachment structure other than the clamp structure may be used to fix and hold the sample 102 in the inspection space S. As long as it can be withdrawn from the inspection space S, it can be provided in any form depending on the shape and structure of the sample 102.

The search gas can be used in various forms as long as it is a mixture of a diffusible gas and an inert gas. For example, helium gas or methane gas can be used as the diffusible gas, or an inert gas can be used. Alternatively, argon gas may be used.

The sample 102 is not limited to a screw-in type pipe joint, but may be a pipe joint formed by integral molding of other structures. Further, the pipe joint is not limited to the integrally molded product, and may be a pipe joint in which a plurality of parts are combined. For example, a cap nut-shaped pipe end connecting portion is provided via a seal member such as an O-ring, screw connection or caulking. The pipe end connecting portion may be integrated with the joint main body. Further, not only the pipe joint, but also a piping device such as a valve may be the DUT 102. When the valve is the DUT 102, various valves such as a ball valve and a gate valve can be inspected for pressure resistance.

The DUT 102 may be a straight pipe joint. In this case, a mounting jig having a straight gas flow path at the clamp portion may be used. Even when the intervals of the flow paths 103 are provided at angles other than 90°, by using a mounting jig provided with a clamp portion corresponding to the angle, a joint of any shape or piping of various structures can be obtained. Can handle parts.

The open/close plate may be made of various materials other than the acrylic plate, and may be set to open at a larger angle than the horizontal direction when fully opened.

Next, the pressure resistance inspection method and operation using the above-mentioned apparatus main body using the search gas will be explained. FIG. 9 shows a flow chart of the withstand voltage inspection method, and FIGS. 10 and 11 show schematic diagrams of the inspection process by the apparatus main body of FIG. In this example, a cloth having a nominal diameter of 3/8 inch was used as the sample.

First, in the state of FIG. 10A and FIG. 11A, the rotating mechanism 113 is operated to rotate the opening/closing plate 111 to the open state (fully open state), and the inspection space S is opened. At this time, the movable jig 122 is moved upward by the cylinder mechanism 123.

In this state, as shown in FIG. 10B and FIG. 11B, the cloth (sample) 102 is placed on the fixed clamp portion 131 of the fixed-side jig 121 so that the predetermined position of the inspection space S is reached. To place. At this time, the open end surfaces 104, 104 of the arbitrary two

branch flow paths

103, 103 of the cloth 102 are placed so as to abut on the two

clamp surfaces

132, 132 of the fixed clamp part 131, respectively, and the protrusions are supported by the protrusions. Make the cloth 102 stable.

In FIG. 10C and FIG. 11C, the cylinder mechanism 123 is operated to lower the movable side jig 122, and the two clamp surfaces 136 of the movable clamp portion 135 are connected to the two branch flow paths above the cross 102. The open end faces 104, 104 of the 103, 103 are brought into contact with and clamped. As a result, the two opening end surfaces 104, 104 on the upper portion of the cloth 102 are closed by the clamp surfaces 136, 136 in a sealed state, while the two opening end surfaces 104, 104 on the lower portion of the cloth 102 are connected to the gas flow path in a communicating state. It is possible to supply the search gas into the cloth 102 from the pressure side connecting portion 133 and exhaust the search gas from the exhaust side connecting portion 133.

10(d) and 11(d) show the state in which the inspection space S is isolated from the outside by operating the rotating mechanism 113 to rotate the opening/closing plate 111 to the fully closed state. At this time, the inspection space S is in a semi-sealed state, and the gas detection unit 125 of the sensor 112 attached to the opening/closing plate 111 is in a state of being close to the cloth 102.

A search gas having a pressure of 1.4 MPa is supplied from the pressurizing side connection portion 133 into the cloth 102, and a withstand pressure test of the cloth 102 is performed. In this case, when the cloth 102 has a porosity due to cracks or cavities, gas leakage occurs outside, and the leaked search gas diffuses into the inspection space S. The quality of the cloth 102 as a product is determined by detecting the search gas with the sensor 112.

After the completion of the pressure resistance inspection with the search gas, compressed air is supplied from the pressurizing side connecting portion 133, and the compressed air is used to air purge the internal flow path from the pressurizing side connecting portion 133 toward the exhaust side connecting portion 133. The residual hydrogen inside is discharged to the outside.

Subsequently, in FIG. 11E, the rotating mechanism 113 is operated to rotate the opening/closing plate 111 to the fully opened state, the opening/closing plate 111 is retracted from the inspection space S, and the gas detection unit 125 of the sensor 112 is positively activated. Try to expose it to the open air. As a result, as shown in the figure, when the cloth 102 is unclamped, there is no possibility that the search gas leaked from the inspection space S will come into contact with the gas detection unit 125, and the influence of the search gas on the sensor 112 is reduced. The next cloth (test sample) 102 can be inspected at an early stage.

In this case, when the opening/closing plate 111 at the time of full opening is opened at an angle larger than the horizontal direction, the sensor 112 becomes farther from the search gas (inspection space S) and the gas detection unit 125 faces the inspection space S. Therefore, the influence of the residual search gas released from the inspection space S to the outside can be further suppressed. Further, if the gas is lighter than air, such as hydrogen gas, it becomes easy to diffuse above the inspection device.
Subsequently, the cloth (sample) 102 is unclamped with the opening/closing plate 111 fully opened, and the cloth 102 is taken out from the inspection space S.

As described above, after the inspection with the search gas is completed, the opening/closing plate 111 is retracted from the inspection space S by the rotating mechanism 113 that is the proximity retraction means, so that the sensor 112 is exposed to the outside air and leaks when the cloth 102 is unclamped. Since the influence of the search gas is reduced, the search gas can be quickly removed from the vicinity of the gas detection portion 125 of the sensor 112, and the time until the next withstand voltage inspection can be shortened.

A through hole 124 is provided in the opening/closing plate 111, and when the sensor 112 is mounted in the through hole 124, the gas detection part 125 faces the inspection space S and is flush with the surface of the opening/closing plate 111 on the inspection space S side. Since the gas is leaked to the inspection space S during the pressure resistance inspection, the gas detection unit 125 contacts the outside air to detect the outside air when the opening/closing plate 111 is rotated in the opening direction. A large contact area can be secured. Therefore, it is possible to effectively remove the residual gas in the vicinity of the gas detection unit 125 and quickly return the sensor 112 to a gas detectable state.

Since the cloth 102 is arranged in the inspection space S and the search gas leaking from the cloth 102 is electrically detected by the sensor 112, the leaking search gas can be accurately detected in a short time regardless of the volume of the cloth 102. Can be detected. As a result, automation can be achieved, an error in the detection result for each worker is prevented, and the inspection time becomes substantially constant. Since there is no need for the operator to check for leaks, the burden on the operator is small, and there is no need to perform post-processing such as drying on each cloth 102 after the pressure resistance test.

10(e) and 10(f) show a state in which the exhaust fan 140 is arranged as a gas diffusion means in the device main body 101 in a direction intersecting with the opening/closing direction of the opening/closing plate 111. When the residual gas (hydrogen) remains above the predetermined level with the fan 140 provided in this manner and the sensor 112 kept in the measurement state even after the inspection is completed, the fan 140 is used to forcibly inhale the vicinity of the sensor 112. Alternatively, forced exhaust may be performed. As a result, the influence of the search gas leaked when the cloth 102 is unclamped can be reduced more quickly, and the next cloth (test sample) 102 can be inspected earlier. As the gas diffusion means 140, something other than a fan may be used.

As described above, the sensor 112 not only detects the gas leaking from the cloth (sample) 102 into the inspection space S, but also detects the search gas remaining in the atmosphere around the apparatus main body 101. It may be operated at a time other than during the withstand voltage inspection. As a result, as described above, the measurement by the sensor 112 is continued even after the inspection is completed, and while the ambient atmosphere is measured by the sensor 112, the gas diffusion means 140 performs the forced intake or the forced exhaust to perform the search gas reduction control. As a result, the search gas can be removed in a short time while grasping the residual degree.

Here, in FIG. 12, in the case where the above gas diffusion means 140 is provided, an example of voltage transition when the search gas (mixed gas of hydrogen 5% and nitrogen 95% in this embodiment) is measured by the sensor 112. It is shown schematically. In the graph, the horizontal axis represents the passage of time and the vertical axis represents the change in the voltage of the sensor 112 with the passage of time.

The sensor 112 was adjusted by a digital potentiometer (not shown), and the reference voltage when the search gas was not detected was 2.0V. Assuming that the sample 102 without leakage is inspected, the change in voltage from before clamping to after measuring the pressure of the sample 102 is shown as a change in the graph. In this graph, when the voltage rises to 2.1 V after unclamping the DUT 102, it is determined that there is a large amount of residual search gas, the fan 140 is activated, and air purge is performed. If the voltage does not drop below 2.05 V, it is determined that there is residual gas, and the next withstand voltage test of the sample 102 is not performed.

(1) to (9) in the graph show the main points during the withstand voltage inspection.
(1) shows the initial voltage of the sensor 112, which is the voltage immediately after the power of the apparatus main body 101 is turned on. In (2), the sample 102 is clamped by the mounting jig 110, the opening/closing plate 111 is fully closed to make the inspection space S semi-closed, and the sensor 112 is zero-adjusted toward the start of the pressure inspection. The reference voltage is set to 2.0V. (3) shows a change in voltage when the DUT 102 is pressurized with the search gas, and the inspection time is set to 30 seconds to check the presence or absence of gas leakage from the change in voltage. In this example, since the test piece 102 has no leakage, the voltage at this time does not substantially change and is maintained at about 2.0V.

(4) shows the voltage when the opening/closing plate 111 is fully opened after the withstand voltage test, and then the DUT 102 is unclamped and removed. After this unclamping, the residual gas in the sample 102 diffuses around the apparatus main body 101, and the voltage of the sensor 112 rises.

In the vicinity of (5), when the measured voltage rises above a preset value (for example, 2.1 V) set in advance as a criterion for determining the presence or absence of residual gas, a fan 140 or an air purge is used to remove residual gas. Let it start. As a result, the residual gas is diffused from the apparatus main body 101, and the voltage starts to decrease. In this way, by forcibly removing the residual gas after unclamping the sample 102, it becomes possible to prepare for the next sample 102 to be subjected to a pressure resistance test.

At (6), when the voltage drops to around the set voltage (for example, 2.1 V), the fan 140 and the air purge are stopped. At this time, the residual gas is almost diffused from the apparatus main body 101.

At (7), the following DUT 102 is clamped by the mounting jig 110 and the opening/closing plate 111 is fully closed to make the inspection space S semi-closed. At this time, the voltage slightly rises due to the gas remaining slightly from the device body 101.

At this time, as shown in the state (8), when the sensor 112 rises to the reference voltage or higher (for example, 2.05 V or higher), it is determined that the gas that interferes with the withstand voltage test remains, and the residual gas remains. The fan 140 and the air purge are activated to remove the gas. In this way, by forcibly removing the residual gas after the second and subsequent clamping of the sample 102, it is possible to continuously perform the withstand voltage inspection.

In (9), when the voltage drops below a set value (for example, 2.05 V or less), the fan 140 and the air purge are stopped, and the next sample 102 is subjected to a withstand voltage test.

As described above, by performing the forced evacuation of the residual gas twice by starting the fan 140 and the air purge during the pressure resistance inspection, the time required for the pressure resistance inspection of the sample 102 can be significantly reduced. In the case of FIG. The time from the power-on of the main body 101 to the start of the inspection of the first DUT 102 can be carried out in about 75 seconds, which enables a quick withstand voltage inspection.

FIG. 13 shows a partially cutaway side view of another example of the withstand voltage inspection device. The same parts as those of the apparatus body 101 described above are denoted by the same reference numerals, and the description thereof will be omitted.

In this apparatus main body 150, the proximity retraction means 151 is composed of a slide mechanism using a cylinder 152, and the opening/closing plate 153 made of an acrylic plate is changed from the closed state shown in FIG. 13A to a frame as shown in FIG. 13B. By sliding in parallel to the length direction of the body 154 and opening the body 154, the region of the inspection space S inside the frame 154 can be opened and closed.

Also in this case, similarly to the rotating mechanism 113 described above, when the opening/closing plate 153 is in the open state shown in FIG. 13B, the gas detection unit 125 of the sensor 112 is in contact with the outside air, and the gas is not in contact with the outside air. It is possible to effectively remove the residual search gas in the vicinity of the gas detection unit 125 while ensuring a large contact area.

In this device body 150, when the sample is clamped, the opening/closing plate 111 slides in the same direction as the cylinder 152, so that space saving can be achieved. Although the opening/closing plate 111 slides in the length direction of the frame body 154, it may be configured to slide in a direction orthogonal to the length direction of the frame body 154. The slide mechanism 151 may be a drive mechanism other than the cylinder 152.

1,102 EUT (work)
10 Leakage inspection equipment 11 Inspection line

Claims

A method for inspecting a sample such as a valve using a search gas composed of a diffusible gas and an inert gas, in which one gas is sealed in the sample at a pressure according to a predetermined concentration, and then the other A method for mixing a search gas, characterized in that a leak test of a pressure device is performed with a search gas having a predetermined concentration by increasing the pressure inside the sample to a test pressure with gas.
The search gas according to claim 1, wherein a pressure ratio of the diffusible gas and the inert gas is sealed in the sample under a pressure ratio of 2.5:97.5 to 5.5:94.5. How to mix.
The method for mixing search gas according to claim 1 or 2, wherein the diffusible gas is hydrogen gas and the inert gas is nitrogen gas.
The method of mixing a search gas according to any one of claims 1 to 3, wherein after filling the nitrogen gas, the pressure of the hydrogen gas is increased to an inspection pressure.
The method for mixing search gas according to any one of claims 1 to 3, wherein after the hydrogen gas is filled, the pressure is increased to the inspection pressure with the nitrogen gas.