Patent ID: 8117899

Claim:
A method for measuring permeability of a gas sample through a thin film or a wall, comprising the steps of: arranging said thin film or wall as a membrane between a first chamber and a second chamber in a sealed way, said membrane separating and sealing said first chamber and said second chamber; causing said gas sample to flow into and out of said first chamber causing a carrier gas to flow into and out of said second chamber, whereby an amount of said gas sample permeates into said second chamber through said membrane over a period of time and is conveyed away from said second chamber by said carrier gas; determining a rate at which said gas sample permeated into said second chamber and was present in the flow of said carrier gas exiting from said second chamber; characterized in that said steps of causing said gas sample and said carrier gas to flow are made at a total pressure of said gas sample and said carrier gas in said first and second chambers at a predetermined value which is higher than ambient pressure; while the total pressure difference between said first and second chamber remains substantially equal to zero.