Smithers measure the porosity and air permeance of a range of porous materials including tissue, paper and non-woven materials for packaging applications such as filters, labels and packaging materials for medical devices.

The permeability of paper to air affects how the material behaves during many conversion and application processes. It can be measured using a range of air leakage instruments of different types:

  • The Bendtsen air permeance tester measures the flow of air through a fixed area in ml/min.
  • The manual Gurley tester measures the time for 100ml of air to flow through a set area.

The Model 4340 Automatic Densometer and Smoothness Gurley Tester

An example of Smithers' Automatic Gurley machine to measure air permeability in paper.

This machine is also available for measuring the air permeability and smoothness of a wide range of materials.

The Automatic Gurley combines the abilities of a low, standard and high pressure manual tester. It uses several state-of-the-art mass flow meters and a servo-regulator, so that both low and high-flow materials can be tested accurately between 0 and 50 Gurley seconds. 

Standards and accreditation

Smithers' UKAS, ISO 17025 accredited testing is performed to British standard, BS 6538: Part 2 (Bendtsen) and BS 6538 Part 3 (Gurley), and international standards, ISO 5636 Part 3 (Bendtsen) and ISO 5636 Part 5 (Gurley).

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