As teaching materials in home economics, a simplified device used to measure air permeability properties of fabrics was developed. Each fabric was fixed on the open ring, made from poly-propylene sheet, and /as put in the cylinder of this device. The air permeability of multiple layers of fabrics was closely related to the air pressure difference of two sides of layers and the flow rate (v) of air through the layers. Both of them were measured as the change of water level, ΔP (mmH_2O), and of v (200cm^3/sec) respectively. In the case of 16 different kinds of fabrics, a plot of ΔP vs. the number of layers of fabrics (N) gave a straight line in the range of N≦5 layers. The slopes of the lines, for fabrics of low air permeability (such as polyester taffeta, nylon taffeta and so on), were larger than those for permeable fabrics (such as cotton shirting, cotton knitting and so on). This device was applied to the following three cases as a teaching material in elementary school; (1) combination effect of three layers of fabrics (two sheets of cotton knitting and a sheet of polyester taffeta), (2) washing influence of cotton shirting, (3) sizing effect of cotton shirting.
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