between the upper and lower chamber ,clamping it. Then do the vacuum for the whole system .Close the lower testing chamber, input test gas in the upper chamber, make sure form constant pressure between the two side of test sample, for differential conditions, the gas will permeate from the high pressure to lower pressure side, by monitoring the pressure of the lower pressure side to get parameters of various kinds testing samples.
Measuring range: 0.02~5000 cm3/m2 .day.0.1Mpa
0.2~50000 cm3/m2