Each sheet of paper, from a simple paper bag to an advanced filter, has an undiscovered characteristic that determines its performance: its impedance to air. That behaviour — which is referred to as air permeance or porosity — is kind of a gatekeeper substance. It dictates if a bag will shield its insides from spoiled air, the speed at which ink will dry on a printed page, or how effectively a filter can operate.
The well-known international standard for determining such an important property is described in ISO 5636-5:2013 – Paper and board — Determination of air permeance (medium range) — Part 5: Gurley method. This international standard gives us a repeatable and accurate method to measure the flow resistance of paper, providing this key number that can help predict real-world performance.
Anyone devoted to the pursuit of paper and packaging excellence needs to have a firm grasp on this standard. At TNV inspection division, we have long catered to providing the best solution for expert, impartial verification of these foundational tests — TNV is an accredited inspection body located right here in Lucknow, a crucial node in Indian industry.
The international standard for Gurley-method determination of medium-range air permeance of paper and board is ISO 5636-5:2013. The test measures how long it takes for a standard volume of air to pass through a standard area of the material at a constant, low-pressure differential.
Air permeance control is a performance-driven design strategy that offers many substantial benefits across a multitude of industries.
The Gurley method is a beautiful test based on a simple principle yet a laborious process with a unique apparatus.
The test is not a direct measure of airflow. Instead, it gauges the time taken in seconds for a specific volume of air (100 ml) to flow through a specific area of the paper (one square inch). The motive behind this is an infinitesimal stable pressure from a vertical cylinder weight. This outcome is expressed in “Gurley seconds.” More seconds indicate a denser and less permeable paper, while fewer seconds indicate a more open and porous paper.
The standard calls for Gurley-type air permeance testers as follows:
What it is: ISO 186 states that a representative sample must be drawn. Most importantly, the test pieces must be equilibrated to a standard atmosphere according to ISO 187 (e.g., 23°C and 50% relative humidity).
Why it Matters: This is not optional. The size of the pores in the sheet is dramatically influenced by the moisture content of the paper fibres, which are known to swell or shrink based on the moisture content. One less variable – your conditioning. This ensures the results are accurate and comparable globally.
TNV, as an Inspection Body accredited by UAF and complying with the requirements of ISO/IEC 17020, is authorized to provide professional third-party witnessing and verification for the whole ISO 5636-5 testing procedure.
Our meticulous verification process includes:
In the world of paper and packaging, controlling the airflow is essential. The greatest assurance that your material satisfies the exact standards that you and your customers demand is independent verification of your testing process.
For professional, accredited, and globally recognized inspection services, Contact TNV Inspection Division today for professional, accredited, and internationally recognized inspection services.
TNV Inspection Division — Your full ISO 17020 accredited inspection partner to ensure your paper products have the performance and integrity.
