Leak and Seal Strength Tester
Application
Tests the compression resistance of various plastic films, aluminum films, paper-plastic composite films, aluminum-plastic composite films and other packaging bags.
1. Significance of Testing
Plastic composite bags are among the most widely used flexible packages in food, pharmaceutical, daily chemical, medical device and industrial sectors. Because they are sealed only by heat-sealed edges, the seal is the weakest link in the whole package. Small drifts in heat-sealing temperature, pressure or dwell time can produce weak seals, channel leaks, micro-holes or seal contamination — defects that are invisible to the eye but decisive for product safety.
During filling, stacking, transport and long-term storage, the package is exposed to internal pressure build-up, compression, drop impact and temperature-humidity cycling. Once the seal strength or the overall pressure resistance is insufficient, the package bulges, bursts or leaks, leading to product deterioration, sterility loss, returns, recalls and financial loss.
Quantitative testing therefore matters. By measuring the burst pressure, the pressure decay under constant load and the time to failure, manufacturers can optimize heat-sealing parameters, verify material and structure selection, screen incoming and outgoing lots, and demonstrate compliance with GB/T 10004, GB/T 18454, GB 19741, ISO 11607-1/-2, ASTM F1140 and ASTM F2054. It turns packaging quality control from experience-based judgement into data-based decision making.
2. Test Principle
The Leak and Seal Strength Tester operates on the positive-pressure (internal pressurization) principle. Compressed air is injected into the inner cavity of the specimen through a sealed inflation head, and the internal pressure rises at a controlled rate. A high-precision pressure sensor together with closed-loop PID pressure control records the full pressure–time curve, while the instrument completes pressurization, pressure holding, timing and pressure release automatically in one touch.
Three test modes are available:
- Burst Test — the specimen is continuously pressurized until it bursts, and the maximum pressure it withstands before failure (burst pressure) is measured. This characterizes the pressure limit of the whole package.
- Creep — the specimen is pressurized to a specified pressure, for example 70% of that maximum pressure, and held for a specified period, during which any change in pressure is observed. This evaluates seal stability under sustained load.
- Creep-to-Burst — the specimen is pressurized to 90% of the maximum pressure and the time taken for it to burst is recorded. This simulates long-term stacking or storage fatigue and yields the time to failure.
Two expansion conditions are supported:
- Unrestrained expansion — the bag inflates freely, stress concentrates at the centre, and the overall pressure resistance of the whole bag is measured.
- Restrained expansion (restraint plate) — the bag is clamped between two rigid plates, stress is redistributed evenly along the heat-sealed edges, and the strength of the seal itself is measured in accordance with ASTM F2054.
In addition, gross leaks can be detected by the internal-pressure method: the specimen is pressurized and either monitored for pressure decay (quantitative) or immersed in water to locate escaping bubbles (qualitative).
3. Test Method
- Specimen preparation — Randomly take sound specimens from the lot (typically 5 pieces). Condition them in a standard atmosphere in accordance with the applicable standard before testing.
- Mounting and sealing — Connect the inflation head to the inner cavity of the bag and seal the connection. An open bag is clamped at its opening; a finished sealed bag is pierced with a hollow needle fitted with a sealing gasket.
- Parameter setting — Select the test mode (Burst, Creep or Creep-to-Burst), then set the pressurization rate, target pressure, holding time and failure criteria.
- Automatic testing — Start with one touch; the instrument automatically performs pressurization, pressure holding, timing and pressure release, and displays the pressure–time curve in real time.
- Result reading and judgement — Read the burst pressure, the pressure decay during holding, or the time to failure. The result is judged pass or fail automatically, with specimen number, test time and curve recorded.
- Data handling — Results are stored, printed or exported via USB for traceability and quality archiving, with Chinese and English report options.
4. Summary
The Leak and Seal Strength Tester is a positive-pressure solution dedicated to packaging bags. With a test range of 0–1000 kPa, accuracy class 0.5, imported SMC pneumatic components and one-touch intelligent control, it delivers three test modes — burst, creep and creep-to-burst — and supports both restrained and unrestrained expansion, providing a complete evaluation of seal quality, seal strength and pressure resistance for plastic composite bags.
The same instrument also covers medical sterile packaging bags, pilfer-proof closures, flexible tubes, aerosol valves and blister packs, and is designed around GB, ASTM, ISO, YBB, BB and QB standards, including ASTM F1140, ASTM F2054, ISO 11607-1/-2, GB/T 10004, GB/T 18454 and YY/T 0681. It is a practical tool for packaging R&D, incoming inspection, process validation and lot release, helping manufacturers reduce packaging failure risk, shorten package qualification cycles and safeguard product quality from the filling line to the end user.
5. Contact Us
Packaging failure rarely announces itself — it shows up as a returned lot, a failed audit or a customer complaint. Let us help you catch it first.
Whether you need to confirm a test method, evaluate your package against ASTM F1140 / F2054 or ISO 11607, or find out how the MF-700D fits your own products, our technical team is ready to help. We offer method consultation, sample testing and customized fixture design.
Contact us
Tel: 15553140527｜ Email: maomao@dansentech.com
Tell us your packaging type and target standard — we will come back with a recommended test configuration and a test report sample.
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