WAFU
Food Flexible Packaging Bag Airtightness Testing Solution
1. Product Overview
Food composite film flexible packaging bags are widely used for: cooked food, dried fruits, meat products, dairy products, frozen foods, vacuum packaging, gas-filled packaging (nitrogen/carbon dioxide), high-temperature cooking bags, etc.;
If the packaging bag is not properly sealed, it will directly affect food safety, freshness, and shelf life:
| Issue | Detailed Description |
|---|---|
| Bacteria/Oxygen Ingress | Food mold and spoilage |
| Gas Leakage | Vacuum failure, swelling, collapse |
| Oil or Liquid Seepage | Appearance contamination, affecting sales |
| Frequent Customer Complaints | Brand reputation damage |
| Sampling Test Failure | Unable to pass QS/HACCP standards or export inspections |
Figure 1: Illustration of Food Flexible Packaging Bag
Case Study
In 2023, a large food processing factory in Shandong experienced swelling and oil seepage during transportation of a batch of high-temperature cooking meat packaging bags for export. Investigation found that some bags had weak heat sealing and micro-leaks at the edges. The factory then introduced airtightness testers (vacuum negative pressure + mass flow methods) for sampling inspection, setting the standard as "negative pressure -30kPa, hold for 60 seconds, leakage ≤5 sccm." Subsequently, the outgoing pass rate significantly improved, successfully restoring stable export delivery.
2. Detailed Professional Testing Solutions
Comparison of Testing Methods
| Method No. | Method Name | Principle | Applicable Scenarios | Remarks |
|---|---|---|---|---|
| 1 | Vacuum Negative Pressure Method (Upgraded Vacuum Submersion) | Creates pressure difference by pressurizing or vacuuming to detect bag leakage | Non-destructive, suitable for vacuum packaging, modified atmosphere packaging (MAP), etc. | Can be combined with airtightness testers for automatic leak detection |
| 2 | Mass Flow Method | Measures volume of leaked gas per unit time | Accurate leak quantification, suitable for high-end MAP bags sampling or full inspection | |
| 3 | Bubble Water Test (Traditional) | Submerge bag in water under pressure, observe for bubbles | Destructive test, suitable for lab sampling validation | Not suitable for large-scale full inspection or automated production lines |
| 4 | Heat Seal Integrity Testing (Auxiliary) | Uses seal strength tester to check seal edge tensile strength for consistent sealing | Often used alongside airtightness testing |
3. Typical Testing Process Demonstration
Using the vacuum negative pressure method as an example:
| Step No. | Detailed Step |
|---|---|
| 1 | Place in testing chamber: Put the sealed flexible bag into the sealed chamber |
| 2 | Start vacuum: Set vacuum pressure (e.g., -30kPa), start evacuation |
| 3 | Observe changes: Maintain pressure, watch if the bag swells, ruptures, or rebounds |
| 4 | Leak detection: Use airtightness tester to monitor pressure/flow changes in real-time |
| 5 | Result judgment: No bubbles or deformation means pass, data is automatically recorded |
| 6 | Output/traceability: Automatic sorting of OK/NG results, upload to MES system for traceability |
4. Conclusion
The sealing quality of food composite flexible packaging bags directly determines product shelf life, compliance, and consumer experience. Using professional airtightness testers for seal testing is a key step to ensure quality, safety, and compliant production.