SU1402820A1 - Method of detecting leakage - Google Patents

Abstract

The invention relates to the field of testing equipment. The aim of the invention is to eliminate the contamination of the test surfaces of the product, increase productivity, which is achieved through the use of: - evaporating tracer substances, and in addition, increasing the accuracy of leak detection in closed products by creating a pressure drop across the walls of the product. The test wall of the product is, on the one hand, treated with a highly evaporated liquid with a freezing point of less than 0 ° C and a coolant. After exposure of the atmospheric air to the opposite side of the wall, leaks of thawing frost are recorded on it. To create a pressure differential, the cavity of the test product is evacuated. 1 hp f-ly.

Description

(L

with:

4 o to

00

Yu

about

The invention relates to a testing technique and can be used to detect "cold leaks in vacuum technology.

The purpose of the invention is to eliminate the contamination of the product surface with the indicator substance by evaporation and increase productivity by eliminating the operation of removing the indicator substance from the test surface, improving the accuracy of leak detection in closed products, which is achieved by creating a pressure differential on the product walls.

The leak detection method is implemented as follows.

On the one hand, the wall of the tested product is wetted with light pulp by means of indicator penetration with high penetrating power and freezing point of less than 0 ° C, and the coolant is applied to the wall of the product from the same side. As a result of the interaction of the cooled opposite side of the product wall with atmospheric air, atmospheric moisture freezes in the form of a white frost layer. As the test product cools, cold leaks open up in it and the indicator substance penetrates through the channels of these leaks to the opposite side of the product wall. At the sites of occurrence of the indicator substance, frost does not form frosting through large leaks, as there is no adhesion of ice crystals to the indicator substance, the freezing temperature of which is less than 0 ° C, i.e., less than the freezing temperature of atmospheric moisture, which makes it possible to register leaks due to thawing points. A small amount of the indicator substance penetrates the surface of the product wall through small leaks and the adhesion of ice crystals of frost to the unfrozen indicator air in these places is poor, which allows small leaks to be recorded on transparent spots of thawing on a white background of frost.

To detect leaks in closed articles using this method, the product cavity is preliminarily evacuated, and then, repeating the operations described above, the presence of leaks in the product is recorded. Pre-evacuation of the cavity of closed products provides the opening of leaks and increases the penetrating ability of the indicator weft due to the created pressure drop on the product walls.

In addition, this leak detection method is applicable to cryogenic vessels operating on a cryogenic liquid (e.g., liquid helium), which contact with atmospheric air at room temperature is unacceptable. Isyntu.my my cryogenic vessel is subjected to the usual for him to vacuum pumping. Then the walls of the inner cavity of the vessel are wetted with an indicator substance.

five

vom and pour cryogenic liquid. After cooling, the test cryogenic vessel is evacuated and removed to “warm it up to atmospheric air. The presence of thawing hoarfrost on the outer surface of the vessel wall indicates the presence of leaks and their local location.

Example. Vacuum the nitrogen cryostat cavity. The indicator substance is poured in, which is used as an evaporating liquid with high penetrating power and a freezing point of less than 0 ° C, for example, alcohol, in an amount sufficient to completely wet the surfaces of the inner walls of the cryostat. Then gradually pour liquid nitrogen. As the inner walls of the cryostat cool down, cold leaks open up, through which alcohol penetrates to the opposite side of the walls, and on them, a layer of frost forms after atmospheric air evaporates. As the surface warms up, the alcohol thaws, resulting in transparent spots on frost, which indicate the location of the cold leaks.

As can be seen from this measure, this method of leak detection does not require additional operations to remove the indicator substance from the surface of the test vessel, since the indicator substance completely evaporates, while the remaining operations of the method are normal working operations for cryogenic devices, which allows improve performance.

In addition, the use of a readily evaporating indicator substance in the proposed method allows it to be used to detect leaks in products in cryogenic devices that prevent contamination of their surfaces with various substances, and the operations of the method are carried out without the use of harmful and dyes that ensures compliance with the safety conditions and production culture.

Claims (2)

Invention Formula . The method of detecting leaks is that the tested wall of the product is influenced by the indicator substance and coolant on one side, and atmospheric air is applied on its opposite side and the leaks are recorded from this side by spots on hoarfrost, distinguished by . that, in order to avoid contamination of the surface of the product with the indicator substance and increase productivity, an evaporating liquid with a freezing point of less than 0 ° C is used as the indicator substance 5, and Spots used to defrost hoarfrost. 0 five 0 1402820 34 2. The method according to claim 1, characterized in that the action of the indicator substance on the wall in order to improve the accuracy of product detection, the cavity of the product on this side Leaks in closed products, before vacuum evacuate.