52


 Gas Pressure
 To Double Stage
 Manomenter Regulator
 00,

 SDrying Gas
 Column inlet



 Capillary ( Pressure
 Tube Oil TrapsY Valve
 S(Buhbber)

 Constant
 Temperature
 Bath


 JPermeab2 Filter Papersatus

 eeaes t oe se o e s specimen esas



 I.I I ,-,, ---- .,
 Exchanger








 Permeability Apparatus

 This apparatus basically consists of a specimen placed between two chambers as


shown in Figure 4-3. The test gas is pressurized in the upstream chamber. The gas


permeates through one side of the specimen and escapes out of the other side. The


escaped gas is collected in the downstream chamber and flows into a glass capillary tube.


The amount of gas escaping per unit time is measured. The permeance is determined by


gas transmitted rate and the partial pressure differential across the specimen. The


permeability P is defined by the product of permeance P and the specimen thickness t.


 The gauge pressure of the gas in the upper upstream chamber is measured using a


pressure transducer (P-303A from the Omega Engineering Inc). The ambient pressure is


measured by a barometric sensor (2113A from the Pasco Scientific). A precision pressure