RU1837176C - Method for testing articles for tightness - Google Patents

Description

flowing from the surface of the inner container of the product 1, and also flowing through discontinuities in the walls of the product. In this case, the gas pressure in the closed shell 5 surrounding the product 1 (for example, in the spacecraft compartment) is equal to Pi, the pressure at which the evacuated product 1 is operated. Then, the gas pressure in the closed shell 5 is increased to Ra, for example, the pressurization of the spacecraft compartment compressed air from cylinder 6, and the total gas flow Oa is again measured. Finally, the total gas flow Oz is measured at a gas pressure in the shell 5 equal to Pz, with Pz exceeding Pa.

If there is a discontinuity in the wall of the article 1, the gas flow through the discontinuity increases with the gas pressure at the inlet of the discontinuity.

The magnitude of the gas flow stripping from the surface of the inner container of the article 1 does not change, and the increment of the total flow

A0a 0s-01 0nz-0n1 A (P3-Pi) + B (P32-Pi2).

(3)

5Reshing system of linear equations (2)

and (3) with respect to A and B, we obtain the following relations:

10

g1

A-RP2-P1) (RZ-RO (RZ-P2) L

(Pz2-P12) AQi- (P22-Pi2) (4)

B (P2-Pi) (Рз-Р2) (Рз-Р1) Г1 15 (Рз-Р1) AQi + () A 02. (5)

If the value of the actual leakage of Ofact, product 1 is taken as the gas flow flowing into the internal cavity of the product at a pressure in the shell 5 equal to PI (for example, equal to atmospheric pressure), then use the relations (4) and (5) we get

25

Ofak AR1 + BP12 (P2-P1) x

AQi Qa-Qi

(and

A Wa Q3-Qi)

equal to the increment of the gas flow flowing through the discontinuity. Thus, an increase in the total flow with increasing gas pressure in the shell 5 indicates the fact of a leak in the article 1. The actual leak is determined as follows. The known dependence of the magnitude of the flow of gas It into the vacuum through the microchannel on the pressure at the inlet to the microchannel (see, for example, Y. Groshkovsky, High Vacuum Technique. M: Mir, 1975, pp. 104-106):

QH Ap + Bp2

(D

where A and B are coefficients depending on the geometric shape and dimensions of the microchannel, as well as on the kind of gas flowing through the microchannel.

From relation (1), the expressions for incrementing the total flow A Qi and AOa follow:

A Qi Qa-Qi 0 on- QHI

 A (P2-Pi) + B (P22-Pi2):

(2)

1-1

Claims (1)

x (P3-Pi) (Rz-Ra) G Pi Rz x x (Rz-RO DSP-Pa (Pa-Pi) AQa. Formula from finding A method of testing the product for leakage, which consists in vacuuming the internal cavity of the article and measuring the total flow of gas separation from the surface of the internal cavity and leakage of the control gas into the internal cavity, characterized in that, in order to provide the possibility of checking the tightness of products having gas separation from the surface of the internal cavity, exceeding the value of the allowable leakage of the product, the product is placed in the chamber, the external gas pressure on the surface of the product is twice increased and additionally measure the value of the total flow of gas separation from the surface of the inner cavity and leakage of the control gas into the inner cavity, and the leakage value of the product is determined from the ratio g1 55 Q (P2-.Pi) (Pz-Pi) (Pz-P2) T, / Pi P3 (P3-Pi) - (Q2-Qi) -P2x x (P2-PiXQ3-Qi). ; where Pi is the working pressure of the external environment; I Qi - the value of the total gas flow | at working pressure; I P2 pressure of the environment with its additional increase; X { Qa is the value of the total gas at an additionally increased pressure; Pz is the pressure of the external environment with a repeated increase in pressure; Oz is the value of the total gas flow upon repeated increase in pressure.