ASTM F2338-09 (2020) pdf free.Standard Test Method for Nondestructive Detection of Leaks in Packages by VacuumDecay Method.
The test package is placed in a test chamber to whichvacuum is applied. The chamber is then isolated from thevacuum source and a pressure transducer (absolute or gauge)alone or in combination with a second differential pressuretransducer, is used to monitor the test chamber for both thelevel of vacuum,as well as the change in vacuum over time.Vacuum decay,or rise in chamber pressure,is a result ofpackage headspace gas being drawn out of the package through any leaks present,plus background noise. Vacuum decay canalso result from the volatilization of packaged liquid thatpartially or fully occludes the leak path. In this case, vacuum decay will only occur if the chamber test pressure is loweredbelow the liquid’s vaporization pressure.
Porous barrier lidded tray or cup packages are tested forleaks located in the tray or cup, and at the lidding material/trayseal junction. Leaks in the porous lidding material itself cannotbe detected. When testing such packages，steps are taken tophysically mask or block the porous barrier surface to preventthe migration of package gas through the porous lid.Thesesteps may require some sample preparation, depending on themasking approach required,but must be nondestructive andnoninvasive. Vacuum decay from porous barrier lidded pack-ages may potentially include background noise from gastrapped between the lidding material and the masking surface,or from transverse gas flow through the porous barrier material
itself at the lid/tray seal junction.The sensitivity of a test is a function of test packagedesign,transducer(s)’sensitivity, test chamber design, test system design,and critical test parameters of time and pressure.The test system and leak test parameters selected for any givenproduct-package system must be based on the packages contents (liquid or solid with significant or little gasheadspace)， and the nature of the package (flexible or rigid,
porous or nonporous). Instruments with more sensitive pres-sure transducers and with minimal void volumes within the testchamber and the test system have the potential to detect thesmallest leaks.Lengthening test time enables smaller gaseousleaks to be detected. Minimizing pressure variation background noise can also improve test sensitivity. For porousbarrier lidded packages，masking techniques will minimizebackground noise.For flexible or semirigid packages, restricting package expansion via properly designed test chamberslessens noise. Background noise may also occur upon releaseof residual gases or vapors trapped in the test system orbetween test package components. Such noise can be differen-tiated from actual leakage by lengthening the time to reachinitial vacuum or lengthening equalization time.ASTM F2338 pdf download.