Airflow

A method of measuring the mean fibre diameter of a sample of wool in which a test specimen (a measured mass of the scoured, dried and carded sample or a measured mass of silver), after exposure to a conditioning atmosphere, is compressed to a fixed volume and a current of air is passed through it. The rate of flow is then adjusted so that the pressure drop across the sample equals the predetermined value, or the pressure drop across the sample is adjusted until the air flow equals a predetermined value. The rate of flow in the first case or the pressure difference in the second case, is an indicator of the mean fibre diameter of the wool in the sample.