抄録
We specially designed a tes_??_er to measure the air permeability of fabrics. The essential part of the tester consists of a blower, a sensitive manometer to measure the pressure difference on the two sides of the fabric, a wind channel in which a circular test piece of 8cm. diameter is held across the direction of air flow, and an electric anemometer to measure the volume of air passed through the fabric.
The result of research can be summerised as follows
1) It was proved that a relation, v=KP1/n where v: volume of air in c. c pased through Icm2 of fabric per seeohd p: pressure differece of air on the two sides of the fabric K, n: Constants depending on the fabric is hold for all fabrics. If we find, therefore, the value of K and n, the permeability of the fabric is known.
2) It is impossible to presume the accurate value of K and n of any type of fabric from its name, for small change in yarn and cloth chracters produces considerable variation in permeability.
3) Air permeability of a pile of same samples was studied, and it was proved that the resistance of single fabric to air passage decreases as the number of layers increases.
4) As the relative humidity of air increases, the value of K decreases, and this tendency is remarkable when the fabric is made of rayon, natural silk or wool.
5) Weave structure itself has little effect on the value of K and n, but it has close relation to the porosity of texture, and so indirectly affects the air permea-bility.
6) There is apploximately linear relation between the value of K and the ratio of appearent hole area to the whole area of the fabric.
7) Fifty common fabrics were selected and their permeability were measured. They gave mean value of 74.9 for K and 1.40 for n.
8) As the ratio of appearent hole area increases, the value of n increases rapidly at first and then rather gradually. It does not reach 1.6 even when the ratio of appearent hole area becomes 70%.
