JPS63157030A - Probe for leak test - Google Patents

Abstract

PURPOSE:To conduct an accurate leak test by blowing gaseous nitrogen for sealing to the joined part of a body to be tested locally and forming a gas film, and preventing a gaseous helium layer for detection from leaking to an atmosphere. CONSTITUTION:The inside 2 of a vacuum container 1 is evacuated by an exhauster 9, and when a specific vacuum degree is reached, a probe 4 is put close to the joined part 3 of the vacuum container 1 to blow the gaseous nitrogen 5A to nearby the joined part 3, thereby forming the gaseous nitrogen layer 5B. The probe 4 performs the evacuation from an exhaust port 7 and recovers the gas of the gas layer 5B so that it is scattered after striking on periphery of the joined part 3. This state is held for several seconds and then the inside surrounded with the gas layer 5B in the space of the joined part 3 and probe 4 becomes a vacuum space 11. Then the gaseous helium 6A is blown to the joined part 3 to form the gaseous helium layer 6B. The mixed gas 8 of the gaseous helium 6A after striking on the joined part 3 and part of the gaseous nitrogen 5A is recovered through the exhaust port 7. The gaseous helium 6A leaking from the joined part 3 to the inside 2 of the container is measured by a helium leak detector 10.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to leak testing of assemblies of nuclear fusion and superconducting experimental equipment, and particularly relates to leak testing of assemblies of nuclear fusion and superconducting experimental equipment, and in particular, to a simple and highly accurate leak test for larger and more complex equipment. This invention relates to a probe suitable for quantity detection.

[Conventional technology]

Conventionally, there are two types of leak tests for test objects using helium leak detectors or gas analysis equipment: For example, as shown in Japanese Unexamined Patent Application Publication No. 58-85129, the test section of the test object is covered with a plastic sheet after each component or assembly is completed, and the space between the test section and the plastic sheet is evacuated.

Injecting helium gas into the space and evacuation are repeated to replace the space with helium gas. Detect the amount of helium gas leaking into the test object using a helium leak detector or gas analyzer.

Also, as shown in Japanese Utility Model Publication No. 58-44352, after evacuating the inside of the test object, the tip of the nozzle tube is brought close to the joint on the surface of the test object, and helium gas for testing is applied to the joint from inside the nozzle pipe. Discharge toward the target.

After the discharged helium gas hits the joint, it is collected into a suction tube that is concentric with the nozzle tube and has a trumpet-shaped tip.

Helium gas leaking into the test object is detected using a helium leak detector or gas analysis equipment.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not allow accurate leak testing of assembled nuclear fusion and superconducting experimental equipment because the large size of the equipment requires masking the entire body, and masking with a plastic sheet is not possible due to the complexity of the shape. It was not possible to measure the amount of leakage, and furthermore, it was difficult to find the location of the leakage. Furthermore, in a method in which helium gas is sprayed onto the joint by bringing the tip of the nozzle pipe close to the joint of the test object, the detection sensitivity is lowered because the helium gas goes around other than the joint where it is being sprayed. Therefore, there was a problem with the reliability of the leak test.

The present invention provides highly accurate leakage detection and
The purpose of the present invention is to provide a probe that can easily detect a leak location.

[Means for solving problems]

The purpose of the above is to prevent the gas discharged from the leakage detection gas spraying tube from spreading to the surrounding area.The gas is sealed from the nozzle part, which is installed concentrically with the detection gas spraying tube and has a protruding tip. A gas film is formed by spraying a sealing gas locally onto the joint of the test object using a recovery pipe placed concentrically between the two gases and inside the tips of both nozzle pipes. This is achieved by injecting the detection gas into the space from the center of the nozzle pipe and adjusting the recovery rate and gas pressure of the recovery pipe at Wl in order to prevent the detection gas from scattering from the space.

[Effect]

The nozzle part that seals the detection gas blows the sealing gas locally onto the joint of the test object from the nozzle pipe that protrudes from the detection gas discharge part, and the exhaust pressure from the recovery port provided in the nozzle causes a gas film to form. It is formed.

Therefore, even if the detection gas is locally sprayed from the center of the nozzle pipe to the joint of the test object, the detection gas will not leak into the atmosphere, and the density of the detection gas will increase.
Highly accurate leak testing becomes possible.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on FIGS. 1 and 2. The nozzle part that seals helium gas 6A is
The sealing nitrogen gas 5A is locally sprayed onto the joint 3 of the test object from the nozzle pipe protruding from the detection helium gas discharge part, and a gas film 5B is formed by the exhaust pressure of the recovery lower provided in the nozzle. be done. Therefore, helium gas H for detection
Since 6B will not leak into the atmosphere and the density of helium will be increased, highly accurate leak tests will be possible.

In FIG. 1, the interior 2 of a vacuum container 1 is evacuated with an exhaust device 9, and when a specified degree of vacuum is reached, a probe 4 is inserted into the vacuum container 1.
Nitrogen gas W5B is produced by blowing nitrogen gas 5A near the joint 3. At that time,
The probe 4 performs evacuation through the exhaust lower, and after the gas in the nitrogen gas layer 5B hits the vicinity of the joint 3, it is collected through the exhaust lower so as not to be scattered. When this state is maintained for several seconds, the space between the joint 3 and the probe 4 automatically becomes a vacuum space 11 surrounded by the nitrogen gas layer 5B.

When helium gas 6A is sprayed onto the joint 3 in the space 11, helium gas ft6B is produced. At this time, the mixture 8 of the helium gas 6A and part of the nitrogen gas 5A after hitting the joint 3 is recovered by the exhaust lower.

A helium leak detector 10 measures the leakage of helium gas 6A from the joint 3 of the vacuum container 1 into the interior 2 of the vacuum container. The effect is the same even if multiple exhaust lowers are provided.

〔Effect of the invention〕

According to the present invention, it is possible to locally form a film with nitrogen gas on the joints of the test object, so even in leak tests of large and complex-shaped devices, there is no possibility of helium gas for detection going around. The amount of leak can be measured with high precision and the location of the leak can be easily discovered.

[Brief explanation of the drawing]

1 and 2 are a front view and a plan view showing an embodiment of the present invention. 1...Vacuum container, 2...Inside of vacuum container, 3...Joint part.

Claims (1)

[Claims] 1. A first nozzle pipe that discharges the leakage detection gas; a first nozzle pipe that is concentric with the first nozzle pipe and arranged on the outer periphery, the tip of which protrudes from the first nozzle pipe; a second nozzle pipe from which gas is discharged to seal the gas, and a recovery pipe disposed concentrically between the second nozzle pipe and inside the tips of the first and second nozzle pipes. A leak test probe characterized by: