ASTM E493-97 PDF

1.1 These test methods cover procedures for testing devices that are sealed prior to testing, such as semiconductors, hermetically enclosed relays, pyrotechnic devices, etc., for leakage through the walls of the enclosure. They may be used with various degrees of sensitivity (depending on the internal volume, the strength of the enclosure, the time available for preparation of test, and on the sorption characteristics of the enclosure material for helium). In general practice the sensitivity limits are from 4.4 X 10 -15 to 4.4 X 10 -11 moles/s (10 -9 standard cm /s to 10 -5 standard cm /s at 0°C) for helium, although these limits may be exceeded by several decades in either direction in some circumstances.

1.2 Two test methods are described:

1.2.1 Test Method A -Test part preparation by bombing.

1.2.2 Test Method B -Test part preparation by prefilling.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.