14-10-2016, 04:12 PM
1459077607-AIRPERMEABILITYslide.pptx (Size: 276.68 KB / Downloads: 6)
DEFINITION
It is defined as the volume of air in cubic cm which pass in 1 sec through 1cm square of fabric under a pressure load of 1cm of water .
WORKING
Place sample of 2.5 gm in case of measurement of pressure while in case of measurement of air we take the sample of 1.5 gm .
Now sample is packed into a container with perforated base.
Compress the sample with rod .
Retaining cap is placed on the sample.
Pump is used to suck the air through the sample.
Pressure across the sample is monitored and with the help of valve it is maintained constant.
Air blow is measured at fixed pressure drop.
Each sample is tested 4 times to give better results.
FACTORS AFFECTING AIR PERMEABILITY
Yarn parameters : yarn twist ,count , structure(ring or airjet yarn etc )
Fabric parameters : fabric weave and thread density
Yarn twist : as the twist is increased there is decrease in flow.
Fabric weave : as the thread spacing is decreased , the type of thread crossing would have significant effect on flow.
Fabric cover factor : air permeability decreases with the increase in cover factor.