RU2079121C1 - Process testing tightness of article - Google Patents

Abstract

FIELD: testing equipment. SUBSTANCE: chamber with article is pumped out. Additional volume communicated with vacuum chamber and connected to leak detector is pumped out with different productivity by evacuated gases. In this case total pumping-out capacity is chosen from necessity of creation of full pressure in additional volume corresponding to minimal full pressure of working pressure range in chamber of mass spectrometer of leak detector. Gas pumping out capacity is chosen from necessity of formation in additional volume of partial pressure of testing gas not exceeding maximum partial pressure registered by leak detector. Calibrated flow of testing gas is fed into chamber and readings are taken from calibrated flow of testing gas by leak detector. Changing flow of analyzed gas from chamber to additional volume till it reaches specified working range of leak detector by registration of partial pressure of tasting gas one feeds flow of neutral gas into additional volume. Its value is changed to obtain full pressure corresponding to maximum reading of leek detector from calibrated flow of testing gas. Article is filled with testing gas and readings from article are measured by leak detector. Lack of tightness of article is determined by analysis of gas from chamber, by relation of measured readings from article and calibrated flow. EFFECT: enhanced sensitivity of test, reduced labour input when testing for tightness.

Description

 The invention relates to the field of testing equipment, in particular to testing products for leaks, and can also find application in those areas of technology where high demands are placed on the reliability of products.

 A known method of monitoring the tightness of products, which consists in placing the product in an evacuated chamber, and the tightness of the product is judged by comparing the concentration of the control gas in the vacuum chamber before and after supplying the control gas to the product using a mass spectrometric leak detector / 1 /.

 The closest in technical essence and the achieved result to the proposed one is a method for monitoring the tightness of products, carried out using the device as follows / 2 /. The method consists in evacuating the chamber with the product placed in it, supplying a calibrated control gas flow to the chamber, filling the product with control gas, measuring the readings from the calibrated flow and from the product using a mass spectrometric leak detector by analyzing the gas from the chamber and evaluating the leakage of the product by the ratio of measured readings.

This method is accepted by the applicant for the prototype. The disadvantage of the analogue and prototype is that when tested for tightness of products they do not provide the required sensitivity of the tests. This is especially true when testing large-sized products in large-volume vacuum chambers (V 300 m ³ and more), where the sensitivity depends on the depth of the vacuum achieved, the amount of gas separation from the test product and leakage into the chamber, the location of the pumped vacuum devices and their performance.

 The objective of the invention is to increase the sensitivity of the tests and reduce labor costs when conducting leak tests.

 The technical result of using the proposed method for monitoring the tightness of products is the expansion of its functionality due to the registration of small leaks during testing, in particular, large-sized products in large vacuum chambers.

The technical result of using the proposed method is also to reduce test time and reduce energy consumption due to the fact that the chamber is evacuated only by mechanical pumps to a pressure of not more than P 5 • 10 ^-1 mm RT. Art. and evacuation of the chamber with high-vacuum units is not required.

The specified technical result is achieved by the fact that in the known method for monitoring the tightness of products, including evacuating the chamber with the product placed in it, supplying a calibrated flow of control gas to the chamber, refueling the product with control gas, measuring readings from the calibrated flow and from the product by a mass spectrometric leak detector by analysis gas from the chamber, the leakage of the product by the ratio of the measured readings in it, the chamber is evacuated to a pressure of not more than 5 • 10 ^-1 mm RT. Art. the leak detector is connected to the additional volume communicated with the chamber, the additional volume is evacuated with different pumped gas capacities, and the total vacuum productivity is selected from the need to create the total pressure in the additional volume corresponding to the minimum total pressure of the operating pressure range in the chamber of the leak detector mass spectrometer, and pumped gas performance is selected from the need to create an additional partial pressure of control gas, not exceeding the maximum partial pressure recorded by the leak detector, after supplying a calibrated control gas flow to the chamber, the flow of the analyzed gas from the chamber is changed to an additional volume until the specified operating range of the leak detector is reached to register the partial pressure of the control gas, and then a neutral flow is supplied to the additional volume gas and change its value to obtain full pressure corresponding to the maximum leak detector reading from a calibrated flow ka control flow of the control gas.

 It is the change in the flow of the analyzed gas from the chamber into the additional volume, as well as the additional supply of a neutral gas flow and its adjustment that lead to the solution of the problem.

 Compared with the prototype, the claimed technical solution reduces energy consumption and test time.

где Q_кт тарированный поток контрольного газа, л•мкм рт.ст./с;
Δα_кт показания течеискателя по тарированному потоку контрольного газа, В;
α_min достоверный отсчет по течеискателю, равный удвоенному значению флюктуации фона контрольного газа в камере, В;
заправляют изделие контрольным газом и изменяют показания от изделия масс-спектрометрическим течеискателем путем анализа газа из камеры;
по соотношению измеренных показаний от изделия и тарированного потока определяют негерметичность изделия по формуле

где Q_кт тарированный поток контрольного газа, л•мкм рт.ст./с;
Δα_изд. реакция течеискателя на поток контрольного газа из течей изделия, В;
Δα_кт реакция течеискателя на поток контрольного газа от тарированного потока, В.The proposed method is implemented as follows:
place the product in a vacuum chamber and vacuum it using mechanical vacuum pumps to a pressure of not more than 5 • 10 ^-1 mm RT. Art. (at higher pressures, a sharp deterioration in the test sensitivity occurs due to a decrease in the mean free path of molecules and an increase in the duration of transients);
they connect a mass spectrometric leak detector, for example, TI1-14, with an additional volume communicated with the chamber and vacuum an additional volume with different capacities for evacuated gases, for example, using a cryosorption pump, while the total vacuum capacity is set so as to obtain the total pressure in the additional volume corresponding to the minimum total pressure of the operating pressure range in the chamber of the leak detector mass spectrometer, for example, up to 7 divisions of the dial gauge The properties of the TI1-14 leak detector detecting UR-14, and the test gas pumping capacity, for example, helium, is set so that the partial pressure of the control gas (the output signal of the UR-14 recording device) does not exceed the maximum partial pressure recorded by the leak detector, for example, by scale "3 • 10 ^-8 " of the recording device, 1, 0 V;
the calibrated control gas flow is fed into the chamber and the readings from the calibrated control gas flow are measured by a TA1-14 mass spectrometric leak detector, changing the flow of the analyzed gas from the chamber to an additional volume until the specified operating range of the leak detector is reached by registering the partial pressure of the control gas, for example, on the scale " 3 • 10 ^-8 "recording device, 2.5 V;
a neutral gas stream, for example nitrogen, is supplied to the additional volume, and its value is adjusted to the obtained full pressure in the chamber of the leak detector mass spectrometer corresponding to the maximum test sensitivity:

where Q _CT calibrated flow of control gas, l • μm Hg / s;
Δα _ct leak detector readings on a calibrated flow of control gas, V;
α _min reliable readout by leak detector equal to twice the value of fluctuation of the background of the control gas in the chamber, V;
fill the product with control gas and change the readings from the product with a mass spectrometric leak detector by analyzing the gas from the chamber;
the ratio of the measured readings from the product and the calibrated flow determine the leakage of the product according to the formula

where Q _CT calibrated flow of control gas, l • μm Hg / s;
Δα _ed. leak detector response to control gas flow from product leaks, B;
Δα _kt leak detector response to the control gas flow from the calibrated flow, V.

Implementation example. Tests were conducted on the tightness of the products of our company in a vacuum chamber having a volume of V 350 m ³ . When testing the prototype, the chamber was evacuated to a pressure of p 5 • 10 ^-4 mm RT. Art. The sensitivity of the tests was SQ _max 5 • 10 ^-3 l • μm RT. st / s The total test time was 10 hours. When tested according to the proposed method, the chamber was evacuated to a pressure of p 1.2 • 10 ^- 1 mm RT. Art. The sensitivity of the tests was SQ _max 5 • 10 ^-4 l • μm RT. st / s Moreover, due to the fact that there was no need to vacuum the chamber with high-vacuum units that consume electricity and require cooling with water, it was possible to save 1,100 kW / h of electricity and 50 m ^{3 of} water. In addition, the total test time was 8 hours.

 The proposed technical solution can significantly reduce the amount of expensive tests, increase the sensitivity of the tests and expand the functionality of the method when testing products for tightness.

Claims (1)

A method for monitoring the tightness of products, including evacuating the chamber with the product placed in it, supplying a calibrated control gas flow to the chamber, refueling the product with control gas, measuring readings from the calibrated flow and the product with a mass spectrometric leak detector by analyzing gas from the chamber, evaluating the leakage of the product by the ratio measured readings, characterized in that the chamber is evacuated to a pressure of not more than 5 • 10 ^-1 mm Hg. the leak detector is connected to the additional volume communicated with the chamber, the additional volume is evacuated with different pumped gas capacities, and the total vacuum productivity is selected from the need to create the total pressure in the additional volume corresponding to the minimum total pressure of the operating pressure range in the chamber of the leak detector mass spectrometer, and the pumped gas productivity is selected from the need to create in an additional partial pressure in volume After the supply of a calibrated control gas flow to the chamber, the analyzed gas flow from the chamber is changed into an additional volume until the specified operating range of the leak detector is reached to register the partial pressure of the control gas, after which a neutral flow is supplied to the additional volume gas and change its value until full pressure is obtained corresponding to the maximum leak detector reading from a calibrated eye control gas.