Direct answer
Select the test around the failure you need to detect. Visual checks find gross defects; squeeze or inversion tests screen obvious leaks; vacuum, pressure-decay, bubble, dye, burst and seal-strength methods address different rigid and flexible pack failure modes.
Why this matters
A pack can look sealed while containing a channel leak or weak seal. The acceptance method should be defined before changing sealer temperature, cap torque or induction power.
Decision table
| Method | Best suited to | Limitation |
|---|---|---|
| Visual and manual screen | Gross damage, missing seals and setup | Cannot detect small hidden leaks |
| Vacuum or pressure decay | Rigid packs or chamber-based testing | Requires stable fixtures and limits |
| Bubble emission | Locating gross leaks | Usually destructive or wet |
| Dye penetration | Locating seal channels | Destructive and method-specific |
| Burst or seal strength | Seal strength and weak areas | Does not always represent leakage |
Information to collect
- Define the failure size and business risk.
- Identify rigid, flexible, porous and product-contact constraints.
- Choose destructive or non-destructive sampling.
- Condition samples consistently after sealing.
- Include transport and storage effects.
- Agree pass/fail limits and test frequency.
Practical method
- 1
Start with a known good and known defective pack.
- 2
Validate the method against real failure modes.
- 3
Control test pressure, time and fixture.
- 4
Trend results by sealing head, material and shift.
- 5
Link failures to containment and corrective action.
Common mistakes to avoid
- Using appearance as the only integrity check.
- Applying one method to every pack format.
- Testing before the seal has cooled or stabilised.
- Changing machine settings without a defined defect.
- Ignoring microscopic or intermittent failures.
Questions people also ask
Is a squeeze test sufficient?
It is useful for gross screening but may not detect small or intermittent leaks.
What is the difference between leak and seal-strength testing?
Leak testing looks for a pathway; strength testing measures the force or pressure the seal withstands.
Can leak testing be inline?
Some pressure, vacuum and vision-based systems can be integrated, but the method must suit the pack and required sensitivity.
How often should packs be tested?
Use a risk-based plan covering startup, material changes, each sealing head and normal production intervals.
Continue from the requirement to the equipment
Use the specialist route that matches the product, pack and process. Final suitability requires representative samples, output targets and site information.