Test gas applicator

Abstract

A test gas applicator (10) for applying test gas to a test object to test for the presence of a leak, the test gas applicator (10) comprising a housing (12) surrounding a test gas volume (14) and having a test gas outlet (24) having a membrane material (28) through which the test gas diffuses and / or permeates.

Description

[0001] This invention relates to a test gas applicator for applying test gas to a sample whose sealing performance is to be tested.

[0002] In vacuum leak detection, the airtightness of a sample is tested. This is done by introducing a test gas (e.g., helium or hydrogen) into the sample's external environment, simultaneously evacuating the sample, and testing the gas drawn from the sample to see if the test gas is present. If the gas drawn from the sample contains the test gas, a leak is indicated.

[0003] In traditional test gas applicators, the test gas is typically drawn from a pressure vessel and applied to the external environment of the sample using a spray gun. The disadvantages are that the test gas supply must be filled under pressure, and more test gas than needed is usually applied. Furthermore, the test gas cloud near the sample can be too large, making it difficult to locate leaks.

[0004] One object of the present invention is to provide an improved test gas applicator.

[0005] The test gas applicator according to the invention is defined by the features of claim 1.

[0006] Therefore, the test gas volume is surrounded by a housing that includes a test gas outlet that connects the test gas volume to the atmosphere surrounding the test gas applicator within the housing. The test gas outlet comprises a membrane material that allows the test gas to diffuse through and / or permeate from the membrane material.

[0007] This allows test gas to be applied from a test gas volume without requiring the test gas inside the housing to be pressurized relative to the outside atmosphere. This eliminates the need for complex depressurization techniques. Due to the diffusion / permeation principle of the test gas, a small amount of test gas continuously flows out of the test gas applicator, so the test gas concentration only increases near the test gas outlet. The test gas applicator can be moved along the test object to detect leaks.

[0008] The test gas outlet can be sealed with a cap.

[0009] The housing can be cylindrical or needle-shaped, with the test gas outlet concentrically formed in the distal region of the housing. An inflation valve can be located on the side opposite the test gas outlet. The housing may include a pressure relief valve in an area of ​​its surface, for example, to ensure that the test gas within the housing comprises only atmospheric pressure.

[0010] Advantageously, the test gas can be helium. The membrane material is configured such that the test gas diffuses through the membrane material without a pressure difference between the interior of the housing and the atmosphere surrounding the test gas applicator.

[0011] The membrane material can be an open-pore felt material. In particular, the test gas applicator can be designed as a felt needle. The test gas can diffuse through the pores of the felt material.

[0012] Alternatively, the membrane material can be a non-porous, closed material, such as silicon, through which the test gas can permeate.

[0013] The exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0014] The attached figure shows a longitudinal section through the test gas applicator.

[0015] The test gas applicator 10 includes a cylindrical housing 12 that completely surrounds the test gas volume 14. A pressure relief valve 16 is disposed in the housing surface of the housing 12 to allow pressure exceeding 110% of atmospheric pressure inside the housing 12 to be prevented when the test gas applicator 10 is filled with test gas.

[0016] A filling valve 20 is located on the front side 18 near the rear end of the housing 12 and is used to fill the test gas volume 14.

[0017] The distal front 22 of the housing 12, opposite the proximal front 18, includes a test gas outlet 24 in the form of a cylindrical opening 26. A membrane material 28 is disposed within the cylindrical opening 26 and is configured to allow the test gas to diffuse through and / or permeate from the membrane material 28. The test gas passes completely through the membrane material 28 solely by diffusion. For this purpose, no pressure difference is required on the opposite sides of the membrane material 28.

[0018] The membrane material 28 is a felt material, which is provided in the form of a cylindrical tube.

[0019] The cylindrical cover 30 is configured to slide airtight onto the distal end of the housing 12, so that no test gas enters the external environment of the cover 30 from the test gas volume 14.

[0020] Test gas volume 14 is filled with test gas in the form of helium through filling valve 20. Pressure relief valve 16 prevents the pressure inside housing 12 from exceeding 110% of atmospheric pressure in the external environment of test gas applicator 10. Once the test gas volume is fully filled, cap 30 can be removed to introduce the test gas into the external environment of the sample, allowing the test gas to diffuse from test gas volume 14 through membrane material 28 and test gas outlet 24. In doing so, only a small amount of test gas flows out of test gas applicator 10 compared to conventional pressurized test gas applicators with spray guns. The tip 32 of test gas applicator 10 can penetrate the surface of the sample so that as the amount of test gas drawn from the sample increases, the tip 32 of test gas applicator 10 is located at a leak point in the sample. Typically, the distal tip 32 then points towards the leak point. Therefore, the leak point can be located in a particularly simple manner.

Claims

1. A test gas applicator (10) for applying a test gas to a test object to be tested for the presence of a leak, the test gas applicator (10) comprising a housing (12) surrounding a test gas volume (14) and having a test gas outlet (24), the test gas outlet (24) having a membrane material (28) through which the test gas diffuses and / or permeates; wherein the housing (12) is elongated and cylindrical, and the test gas outlet (24) is concentrically arranged at a distal end of the housing (12); the test gas outlet (24) is provided as a cylindrical opening within the housing (12), the membrane material (28) completely filling the cylindrical opening; wherein the test gas applicator (10), the test gas outlet (24) and the membrane material (28) are configured to deliver the test gas only by diffusion and / or permeation from the test gas volume (14) into the atmosphere surrounding the test gas applicator (10).

2. The test gas applicator (10) according to claim 1, characterized in that the membrane material (28) is configured to diffuse or permeate a gas contained in the test gas volume (14) into the atmosphere surrounding the test gas applicator (10) at atmospheric pressure.

3. The test gas applicator (10) of claim 1, wherein, the membrane material (28) is an open-cell felt material or a non-porous, closed membrane material.

4. The test gas applicator (10) of claim 1, wherein, the housing (12) comprises a fill valve (20).

5. The test gas applicator (10) of claim 1, wherein, the housing (12) comprises a pressure relief valve (16).

6. The test gas applicator (10) of claim 1, wherein, the test gas applicator (10) comprises a safety cap which, when fitted on the housing (12), completely covers and seals off the test gas outlet (24).

7. The test gas applicator (10) according to any one of claims 1 to 3, characterized in that the membrane material (28) extends from the test gas outlet (24) into the test gas volume (14).

8. The test gas applicator (10) according to claim 1 or 2, characterized in that the test gas volume (14) comprises a test gas having an atmospheric pressure. the test gas volume (14) comprises a test gas having an atmospheric pressure.

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