regulator provides constant gas pressure to the upstream chamber. The ambient

temperature was measured using a glass capillary thermometer.





 ion Pressure
 Regulator .--Force Gauge

 1 ( Downstream Chamber

 S....... -a* Outlet Vatve
 "'"'[-c Upstrearn Chmber
 Outlet Valve






 Capillafy Tube --ow-






Figure 4-3. Permeability testing apparatus.

 The specimens are mounted horizontally between the upstream and downstream

chambers and clamped firmly by applying a compressive load as shown in Figure 4-4.

The specimen is sealed with a rubber gasket and an O-Ring (38 mm inner diameter). A

force gauge mounted at the top measures the compressive load to ensure that the same

amount of compressive load is applied on the specimens for every test. The compressive

load should be enough to prevent gas leakage, but should not damage the specimens. The

upstream chamber has an inlet vent and an outlet vent. The inlet vent allows the gas flow

into the upstream chamber and the outlet vents is used to purge the test gas to atmosphere