SU1679229A1 - Method for checking large, long articles for tightness - Google Patents

Abstract

The invention relates to non-leaktightness tests, can be used to localize leaking zones in the shells of large-sized long products while also determining their total tightness and provides control in the case when the product is filled with test gas by sequential supply of test and ballast gases. The product is placed in a vacuum chamber with a leak detector and several test leaks connected to it. The chamber is evacuated, the leak detector is calibrated sequentially for each test leak by recording the time of occurrence and the magnitude of the leak detector signal. The product is filled with the test gas. After receiving the steady-state signal of the leak detector from the product, the pressure of the test gas in the product is reduced by at least 0.1 test pressure, the time and the decrease of the leak detector signal are recorded, and the leakage zone is determined by the ratio of the time of signal change to this change. 4 il. 4 V Ј

Description

The invention relates to leak tests and can be used to localize leaking zones in the shells of large-sized long products while also determining their total leakage.

The aim of the invention is to expand the technological capabilities of the method by providing control when filling with the test gas by sequential supply of test and ballast gases.

Figure 1 shows the vacuum circuit for carrying out the proposed method; FIG. 2 shows the recording of a leak detector signal from a test leak; in FIG. 3, the recording of the signal of the leak detector during filling of the product with the test gas and with a decrease in the pressure of the test gas; in fig. 4 shows graphs of the ratio of the time of occurrence of a leak detector signal to its magnitude, depending on the location of test leaks along the length of the chamber for different values of leaks.

The method is carried out as follows. Article 1 is placed in chamber 2. The chamber is sealed and pumped out by mechanical pumps 3 and high-vacuum aggregates 4. Calibration is performed — each of the control leaks 5 is opened in succession and the signals of the leak detector 6 are recorded on a tape of a self-recording potentiometer 7 similar to that shown in figure 2. Calibration is performed several times, each time

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control leaks 5 with other values of the control gas flow. On the basis of the records received, the values of m / a, the ratio of the time of occurrence of the signal of the leak detector 6 to its value, are determined.

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- the ratios of the values of con to a.

The pilot leaks 5 values of the set signals "to the leak detector 6, respectively, for the most close to the leak detector 6 leak 5 and the most separated from it during calibration.

The test article 1 is successively filled with test and ballast gas and from stand 8, and a leak detector signal is recorded. After receiving the steady-state signal, the Otechi lower the pressure of the test gas in the product by at least 0.1 test pressure to compensate for instrumental errors. On the tape recording potentiometer 7 get a curve similar to that shown in Fig.Z. The magnitude of the signal change is given. Give the magnitude g / Aa. Counting-max Omaks Leaks Leaks And

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From the obtained m / a values, a family of curves is constructed, similar to that shown in Fig. 4. Next, on the ordinate axis of the graphs obtained, the value of g / Da is set aside. From the obtained point, a straight line is drawn parallel to the abscissa axis, up to the intersection with the curves corresponding to the values of LEARN and. From the intersection points, perpendiculars are lowered on the abscissa axis, marking the LMHH points

LMSKC. The LMHH-LMSKC section defines a leakage zone.

The method allows monitoring in the case of sequential supply of test and ballast gases to the product when there is no linear section on the recording curve of the leak detector signal and increasing the signal.

Fogrulz invention

The method of controlling the tightness of large-sized long products, which consists in placing the product in a vacuum chamber with

With a leak detector and several control leaks installed along the length of the chamber, the chamber is evacuated, the leak detector is calibrated successively for each control leak by recording the occurrence time and signal value of the leak detector, the products are filled with a control gas, the time of the leak detector signal change is measured, and the area leaks are determined by

the ratio of the time of change of the signal to the magnitude of this change, characterized in that, in order to expand technological capabilities by providing control when filling

control gas by sequential supply of test and ballast gases, after receiving the steady-state signal of the leak detector from the product, reduce the pressure of the control gas in the product, and measuring

the time and magnitude of the change in the signal of the leak detector is carried out during the reduction of the signal.

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Claims (1)

10 Fogmula of the invention A method for monitoring the tightness of large-sized long products, namely, that the product is placed in a vacuum chamber with a leak detector connected to it 15 and several control leaks installed along the length of the chamber, the chamber is evacuated, the leak detector is calibrated sequentially for each control leak by recording the time of occurrence and size the leak detector signal, the products are filled with control gas, the time of the leak detector signal change by a specified value is measured, and the leakage zone is determined by 25, the ratio of the time the signal changes to the magnitude of this change, characterized in that, in order to expand technological capabilities by providing control when filling 30 with a control gas by sequentially supplying test and ballast gases, after receiving a steady-state leak detector signal from the product, the pressure of the control gas is reduced in product, and the measurement of 35 time and magnitude of the change in the signal of the leak detector is carried out during signal reduction.