SU1364938A1 - Method of determining local leaking of hollow articles - Google Patents

Abstract

The invention relates to methods for testing leak tightness in a vacuum chamber and allows local leakage in a product of a complex configuration to be determined. Chamber 1 is evacuated, and article 3 is filled with nitrogen. A discharge tube 7 with a layer 9 of a chemisorbent (phosphorus) in the interelectrode space is moved along the product. When tube 7 is placed over the furnace, the outgoing nitrogen under the action of the high-frequency field dissociates into chemically active atomic nitrogen, which is chemisorbed by a layer of phosphorus and does not enter the volume of chamber 1. The location and value of leakage is determined in the pressure drop in the chamber. 1 il.

Description

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The invention relates to a test apparatus, namely to methods of leak testing in a vacuum chamber.

The purpose of the invention is the expansion of technological capabilities by ensuring the control of products of complex configuration.

The drawing schematically shows a device for implementing the method.

In the vacuum chamber 1, equipped with a pumping group consisting of diffusion and mechanical pumps 2 and 3, a checked item 4 is placed, communicated with the system 5 of charging with test gas. The chamber 1 is equipped with sensors for measuring the vacuum level 6, and inside the chamber 1 it is movably positioned in contact with one product 4 with the discharge tube 7 with two electrodes 8 and placed in the interelectrode space a layer 9 of chemisorbent, for example, phosphorus.

The method for determining the local leakage of products is carried out as follows.

After loading the product 4 into the vacuum chamber 1 and withdrawing the pumps 3 and 2 of the chamber 1 to a certain vacuum level detected by the sensors 6, the discharge tube 7 begins to move in any of the directions indicated by the arrow using the movement mechanism in a vacuum (not shown). In the interelectrode space of the discharge tube 7 from an external source, a high-frequency electric field is created and the vacuum level corresponding to the background component of the test gas (nitrogen) in the vacuum chamber 1 is measured. Then the product 4 through the system 5 is filled with nitrogen to pressure and again measured by sensors 6 vacuum level in the chamber 1. In the presence of a leak in the zone of contact of the discharge tube 7 with the product 4, the nitrogen penetrating into the interelectrode space under the action of the high-frequency field dissociates into a chemically active atomic field. This is absorbed by the phosphorus layer 9 with the red phosphorus formation reaction. The active nitrogen absorption process reduces the level of vacuum in the vacuum chamber 1, according to which, at a constant pumping rate of chamber 1 by pump 2, it is possible to judge the magnitude of local leaks

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in the tested area of the product, fixed by the location of the discharge tube 7.

The method does not require the use of expensive test gases, since the tests are carried out when the product is filled with common nitrogen, almost neutral under normal conditions (the nitrogen becomes chemically active at high temperatures and pressures or in the presence of a catalyst), which eliminates the interaction of the test gas with inner surface of the inspected: product.

The method is applied when the mechanical cut-off of the leakage place from the volume of the vacuum chamber 1 is not possible when inspecting items with a complex spatial configuration, equipped with unpressurized heat-insulating materials and non-hermetic fairings or housings.

In this case, the chemisorption pumping from the leakage zone is preferable and provides a change in the vacuum level in the volume of the vacuum chamber with the registration of the leakage zone.

Claims (1)

Invention Formula The method of determining the local leakage of hollow products by placing the product in a vacuum chamber, filling it with a test gas, vacuuming the chamber, measuring the pressure of the test gas in the chamber, sequentially isolating the probable gas from the controlled areas of the product from the chamber volume and determining the leakage location from the position of the insulated plot at the time of pressure reduction of the sample gas in the chamber, and the value of non-leakage, by the value of the decrease in this pressure, characterized in that broadening technological capabilities by ensuring control of products of complex configuration; sequential isolation is carried out by creating a high-frequency electric field in the controlled area and placing in this zone a chemical that absorbs the test gas activated by the action of this field.