ISO 7231 permeability test machine Polymeric materials, cellular, flexible — Determination of air flow value at constant pressure-drop This document specifies two methods for determining the air flow value of flexible cellular polymeric materials:

—     method A, for conventional types of flexible cellular polymeric material;

—     method B, for all types of flexible cellular polymeric material, but especially for materials with a low permeability to air.

For method B, two methods are specified in this document:

—     method B1: with manual measurement;

—     method B2: with automatic measurement.

NOTE 1       Air flow values can be used to give an indication of the effects of formulation and production variables on the cellular structure.

NOTE 2       In this document, the expression “conventional type of flexible cellular polymeric material” means types which are unsuitable for sealing purposes.