ASTM E 493/E 493M:2011

1.1 This practice covers 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 10 - 10 to 10 - 6 Pa m³/s (10 - 9 standard cm³/s to 10 - 5 standard cm³/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 Units - The values stated in either SI or std-cc/sec units are to be regarded separately as standard. The values stated in each system may not be exact equivalents: therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. 1.4 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.

19.100