SU1717981A2 - Method of testing article fluid tightness - Google Patents

Abstract

The invention relates to the monitoring of the leaktightness of products and makes it possible to increase the information content by determining the number of leaks and sensitivity. The product is filled with liquid, and the leak detector is measured against the background of the leak detection system. The liquid together with the product is cooled and held for a certain time. The leakage of the fluid is recorded by the leak detector before the background value is obtained. The liquid from the product is drained, maintaining the test pressure in the product. The leakage is determined by the difference in the maximum reading of the leak detector at the source of liquid after draining the liquid and background reading. The number of leaks is determined by the characteristic changes in the leak detector signal, i.e. by the number of bursts of the signal. 2 Il.

Description

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The invention relates to the field of testing, in particular to methods for monitoring the tightness of products, and can be used in the engineering and other industries.

There is a known method of controlling the tightness of products, which consists in filling the product with liquid and measuring the amount of liquid vapor outside the product, moreover, before measuring the leakage, the liquid from the product is drained.

However, this method does not allow to determine the number of leaks on the product, and is also not sensitive enough.

The purpose of the invention is to increase the information content by determining the number of leaks on the product and increasing the sensitivity.

The goal is achieved by the method of monitoring the tightness of products, which consists in filling the product with liquid and measuring leakage of liquid vapors through leakage after draining the liquid from the product, the liquid is cooled before draining, and the number of leaks is judged by characteristic changes in the leak detector signal.

Figure 1 shows the experimental setup for implementing the method; figure 2 is a diagram of the result of the experiment.

In figure 2, the following designations are given: “f is the background signal of the leak detector; “Ed. 1 — leak detector signal for liquid leakage through micro-densities when a sample is filled with liquid;

.2 - leak detector signal after moving the meniscus in the microchannel after the liquid evaporates;

.2 - leak detector signal after moving the meniscus in the microchannel after the liquid evaporates.

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The evaporation of a liquid from the surface of the product after it is drained is uneven, i.e. Some areas of the surface dry out faster than others, as a result of which, if the product has several leaks, the effect of meniscus movement in microchannels occurs non-simultaneously. As a result, the signal recording the increase in the flow rate from the microchannel has characteristic changes in which the number of leaks is judged. In order to spread these changes over time and to make them more pronounced, they slow down the evaporation process by cooling the liquid.

In addition, the cooled liquid has an increased surface tension, and since the movement of the meniscus caused by the action of surface forces increases with increasing capillary and surface forces, the effect of increasing the flow rate and relative signal increment in the case of cooled liquid is higher than that of the heated that increases the sensitivity of the control.

The method of controlling the tightness of the product is carried out as follows.

Controlled product 1 is placed in a snap 2. Set the leak detector 3 to detect leakage of liquid vapors. The background of the leak detection system is measured. The product 1 is filled with a liquid 4. Under the action of capillary forces, the liquid is drawn into the through microchannels 5 and 6 of the product wall. Cool the liquid together with the product and stand for a certain time. Record the leakage of the liquid by the leak detector 3. The signal of the leak detector is recorded on a chart recorder of a recording device. The signal is recorded until its background value is obtained. Drain the liquid from the product, maintaining the test pressure in the product. After draining the liquid, the flow of liquid from the microchannel increases, which is recorded by the leak detector. The leakage is determined by the difference in the maximum reference of the leak detector to the outflow of liquid after draining the liquid and the background reading obtained before filling the product with liquid. The amount of leaks is determined by characteristic changes in the leakage signal.

tel i. by the number of bursts (steps) in the diagram.

Example. Sample 1 (Fig. 1) was placed in snap-in 2. On the sample there were two microchannels: 5 — with a tightness value of l.m.m.rt./s and 6 — with a leakage value of 1l.m.m.rt./s. The entrance to the mouth of microchannel 5 was located above the entrance to capillary 6. On one side, sample 1 was connected to an LHM-80 chromatograph used as leak detector 3, the other side formed a bath into which working fluid 4 was poured. In the experiment, freon was used as a working fluid - 113.

The background of systems 2f was measured (figure 2). The working fluid was cooled to a temperature of about -10 ° C and poured into the bath. After pouring refrigerant - 113, the signal of the leak detector increased to the value of aizd.1. After evaporation of refrigerant - 113 over microchannel 5, the signal increased to the value of a. Ed. 2, after evaporation of liquid over microchannel 6, the signal changed to a value of ed 2, then the signal decreased to a background value, which corresponds to complete evaporation of freon - 113 of the microchannels. sample 1.

According to the experiment, the sensitivity of the proposed method compared to the known increased by 10 - 15%, according to the analysis of the chart confirmed the presence of two microchannels in the sample.

Economic efficiency in applying the proposed method is achieved by detecting leaks at the stage of manufacturing the product, which reduces the cost of subsequent repairs.

Claims (1)

Invention Formula The way to control the tightness of products auth.St. No. 1652845, characterized in that, in order to increase the information content by determining the number of leaks and increasing the sensitivity, the liquid is drained before draining the product, and the number of leaks is judged by the change in the output signal of the leak detector. L X & ed.2 rt ed. 2 з.изд.1 &.R - FIG. one