Differential Pressure vs. Equal Pressure Methods Tester for Measuring Film Gas Permeability

Keywords: Film Permeability Testing, Differential Pressure Method, Vacuum Process, Volume Method, Equal Pressure Method, Oxygen Permeation Testing

Film permeability testing plays a crucial role in material and quality control for flexible packaging. This report focuses on two main test methods for auto gas permeability: differential pressure and equal pressure.

Differential Pressure Method

The differential pressure method is the established standard for scientific research due to its versatility and ability to test various gases. It operates by creating a pressure difference across the film sample. Two sub-methods exist within this category:

Vacuum Process: This method utilizes a 0.1MPa pressure difference to measure gas transmission rate. High-precision vacuum gauges ensure accurate and repeatable measurements.

Volume Method: This simpler and cheaper alternative eliminates the need for a vacuum state, making instrument manufacturing less complex.

C106H Gas Permeability Test System is based on the differential pressure method, and is professionally applicable to the determination of gas transmission rate, solubility coefficient, diffusion coefficient and permeability coefficient of plastic films, composite films, high barrier materials, sheets, and metal foils at different temperatures. The test system conforms to GB, ISO, ASTM and other international standards.

Equal Pressure Method

Primarily used for oxygen permeation testing, the equal pressure method employs a sensor to detect oxygen permeating the film under a difference in oxygen partial pressure. While simpler to operate, the sensor requires periodic replacement due to its consumable nature. But with the latest Labthink technical achievements Coulometric Oxygen Sensor has a service life twice the service life of a traditional Coulometric sensor.

C403H Oxygen /Water Vapor Transmission Rate Test System is based on the testing principle of Coulometric oxygen sensor and infrared water vapor sensor. Its duo sensors allow it to test oxygen and water vapor transmission rate in one instrument, greatly enhance the test precision and efficiency. The instrument conforms to ASTM D3985、ASTM F1249，ISO 15106-2, etc. It is suitable for testing the oxygen and water vapor transmission performance of films, sheets and related materials in the fields of food, medicine, medical devices, daily chemicals, photovoltaic, electronic and many others.

Comparison and Conclusion

The differential pressure method offers advantages in versatility, accuracy, and the ability to test various gases. However, the equal pressure method provides a simpler and potentially more cost-effective solution for specific oxygen permeability testing. Both methods have their limitations, and the choice depends on the specific testing requirements.

Future Trends

Advancements in technology are continuously improving instruments used in these methods. These improvements focus on enhancing precision, expanding functionalities, and incorporating features like temperature control.

As the demand for functional packaging materials grows, testing methods are evolving to ensure a more comprehensive evaluation of packaging films.

Labthink encourages collaboration with packaging industry companies for quality control! Visit the website www.labthink.com to learn more!