3. Measuring equipment

3.1 State of the art

Publications on the air permeability of a large half of the XX ^e century have been devoted as much to results as to the design and development of measuring equipment. Only the principle based on the circulation of an air flow through the textile material led to the description of devices that gradually became commercially available. These instruments were rapidly classified into three types, depending on the expression of the measurement. This classification is still valid today, and examples of companies marketing these devices are quoted.

Shirley-type permeabilimeter: a device for measuring the speed of air flow through a fabric by creating a defined air pressure differential...