Tips and Techniques for Testing Induction Seal Leaks

One of the most frequently asked questions we receive is how to test for leaks. Unfortunately, there is not a simple answer to this question. There are no ASTM specifications, or guidelines relating to the testing of induction seals. Everyone seems to do it "their way."

Here at Enercon, we use several different methods to test the integrity of a seal. It varies based on how detailed the packager wants to get. We can incorporate two types of vacuum test systems, one a dry method and a water method.

The dry method uses a bell jar vacuum chamber which allows you to see at what pressure a seal fails. A more precise method, which allows us to see leaks on a much smaller scale, uses a water bath vacuum chamber. Using this method we see air starting to escape from the sealed package in the form of bubbles from the submerged package. It also allows us to test to the point of seal failure as well. This exact level is going to vary from package to package.

Some companies take pressure testing a step further. A large food packager has an altimeter attached to their vacuum chamber.  To pass the test packages need to maintain their seal up to 36,000 feet on the altimeter. Their reasoning: the product will never be at a higher altitude. While this works well for that specific package, it’s up to each packager to determine their standards.

A simpler method is simply to remove the closure from the sealed container, turn it upside down, or on its side and squeeze. This is a good test to get a feel for the strength of the seal.  However, you may have a microscopic leak that will not be detected with this method. 

From personal experience, another risk with this procedure is the possibility of ending up with product all over yourself, your colleague or the floor.

One of the less sophisticated methods is to remove the closure and stand on the bottle. Honestly, there are customers that do this! Fortunately, if you have a good seal, this method will work. Unfortunately, there is a good possibility you will end up with a mess.

 A number of manufacturers are making production speed systems that will inspect your bottles for leaks without removing the caps. Contact us for more information.

How do you test your containers? We would love to hear from you if you have a method that is not mentioned above. If you do have a good procedure, and would like to share it, let us know.

Enercon's induction sealing laboratory features a vacuum leak tester. It is effective at discovering microscopic leaks.