You should know that sachets are packages that present several difficulties in terms of leakage testing:
1- Lack of Air
Generally, there is little air in the sachet, so this can cause 2 problems at the moment of leak detection:
1-1 When we do the immersion test in a vacuum chamber → ASTM D3078, we may not be able to create enough pressure difference on the walls of the package to be able to observe the leaks. This will depend on the size of the sachet and the volume of air remaining inside.
1-2 Even if the conditions are ideal for testing in a vacuum chamber, if a leak occurs, only a few bubbles will escape from the bag for 5 to 10 seconds. The pressures will quickly equalize and all the air will have been sucked out. So the operator must be attentive and observant. → The test becomes very subjective.
Solution: Do the test by injecting air -> internal pressurization in the sachet (bag) with a needle: ASTM F2096 standard
2- Low viscosity index of the product
The other difficulty is the product it contains.
The lower the viscosity index of the product (gel or peanut butter), the more likely it is that the product itself will block any leaks and prevent the expulsion of air (bubbles) or the flow of product. This phenomenon is unfortunately difficult to detect. The only solution is to do validation tests with empty products or with a product with a higher viscosity index.
So you will have understood, it is not simple.
If it suits you, I can quote you a CDV2 vacuum chamber (28x20x20cm) SVVI (SemiAuto, Vacuum, Venturi, Immersion) with PI option (Internal Pressurization). So you can do tests according to the D3078 and F2096 standards.
We have published some videos on Youtube that show how you can perform a leak test on sachets:
🎥 https://youtu.be/_1ErmBGiyVU