Is there a rule of thumb for channels or voids in a seal area?
The medical device industry generally classifies the presence of any channel that passes through the entire heat seal as a breach of sterility and is therefore unacceptable. The presence of voids in a heat seal is sometimes evaluated in a different manner. Some packaging engineers choose to perform a package validation with the worst-case scenario seal. For example, if a medical pouch has a ⅜-in. ±⅛-in. wide heat seal, a package validation on pouches with ¼-in. may be subjected to distribution testing. This will ensure pouches that possess the minimum seal width of ¼-in. will still pass a distribution test. This logic is then applied to a void in the seal area; if the void interrupts less than ⅛-in. of the seal, the pouch is accepted. If the void interrupts more than ⅛-in., the pouch is rejected as this represents a condition that has not been evaluated by the packaging engineer.