Commonly used standard leaks reachs its demarcate method
From;    Author:Stand originally
Standard leaks is the element that offers foregone gas discharge to vacuum system interior below certain condition. Should make clear this throughput commonly (leak namely rate) the condition such as aeriform sort, temperature, pressure. If not only,fasten demonstrate, show temperature is 1.01×10 for pressure of 296±3K, entrance5Pa, outlet pressure under 1.33×103The dry air of Pa (temperature of its dew point under 248K) leakage rate.
The standard leaks with commonly used 1.
Glass is capillary model standard leaks is the glass that uses local fine-draw capillary make, leakage rate is 10- 8~10- 7Pam3/ S.
Leaks of metallic squash standard is to use the copper that do not have oxygen to cut down is in charge of suppress and may be become normally, leakage rate is 10- 8~10- 6Pam3/ S.
Leaks of vitreous platinic silk standard is use glass and platinic silk not match sealing is made. It is 0.1~0.5mm when platinic silk diameter; Seal when receiving length to be 5~10mm, leakage rate is about 10- 7Pam3/ S. When temperature is changed, its leakage leads change.
Leaks of filmy ooze helium standard is to use what the ooze helium rate of filmy ball bubble makes quartz, its leakage rate is commonly 10- 5~10- 9Pam3/ S. Because temperature is right the impact that leakage leads is very big, when using, ought to notice to amend.

The calibration of 2. standard leaks
The method of commonly used calibration of standard leaks has law of the step up that decide a look and leak detector of helium mass spectra to compare a standard.
(1) law of the step up that decide a look
Via smoking V of roast cubage beforehand hind, standard leaks carries pressure P into gas1< 1.33×103Pa, and V achieves ultimate vacuum. It is 1.01×10 when pressure5The calibration gas of Pa (for example N2Gas) V of cubage of inpour of classics standard leaks, press force P in V2After stability, shut valve S2Clock and environmental temperature T, measure the step up Δp that gives corresponding Δt time2Criterion the leakage rate of standard leaks can be calculated piece.
(2) the comparison of leak detector of helium mass spectra law
In requirement of leak detector work changeless premise falls, measure a foregone leaks L early or late1And wait for school leaks L2the helium that take energy of life is pressed and question mark, the leakage rate that needs school level leaks is calculable piece. QL, 01- L of foregone standard leaks1leakage rate; P1, P2- it is L respectively1, L2Leaks carries helium pressing into gas; I1, I2- it is L respectively1
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