Patent ID: 8015857

Claim:
A method for measuring the permeability of a sample gas through a container or a sealing element, said container or said sealing element having an outer face, an inner face, and a thickness containing a measured starting concentration of the sample gas, said method comprising the steps of: exposing the outer face of said container or sealing element to a fixed flow rate of said sample gas; exposing the inner face of said container or sealing element to a flow rate of carrier gas, said carrier gas being different from said sample gas; contacting the inner face with said carrier gas and measuring the sample gas that has permeated through said container or sealing element and is conveyed by said carrier gas; awaiting a steady condition of measured permeated gas value, whereby said measured permeated gas value represents the permeability of the container or sealing element to the sample gas; whereby said method is further characterized in that: a) said concentration of the sample gas to which said outer face is exposed is chosen such that the difference between the concentration of the sample gas to which said outer face is exposed and said sample gas starting concentration in said thickness is substantially equal to the difference between (a) the sample gas starting concentration in said thickness and (b) an expected concentration of sample gas to which said inner face is exposed, wherein the sample gas starting concentration in said thickness is calculated by assuming a solubility coefficient close to 1.