Patent ID: 7178384
Filing Date: 2007-02-20
Classification: G01N

Abstract:
1. A method for measuring ultralow permeation through an adhesive perimeter using a radioactive compound, which method comprises the steps of: mounting a line of adhesive through which permeation is to be measured between two plates so as to provide controlled access to an upstream surface of the line of adhesive in a first chamber and to a downstream surface thereof in a second chamber, wherein said second downstream chamber has a volume of not greater than about 10 cm supplying a radioactive gas from a source to be in contact with the upstream surface of the line of adhesive in the first chamber, collecting radioactive gas permeating from the downstream surface of the sample by circulating a very slow flow of dry carrier gas at a rate of not greater than about 1.5 liter per hour through the second chamber to provide a radioactive stream, flowing said radioactive stream from said second chamber to an entrance to an ionic chamber not greater than about 2 liters in volume containing a beta-particle radiation monitor, continuously monitoring said stream for beta particle radioactivity and generating signals, and receiving signals from said radiation monitor in conversion means and converting the signals to calculate the permeation rate through the sample at that moment, whereby the sensitivity of the method allows measurement of permeation of radioactive gaseous compounds through lines of adhesive that have barrier properties which permit permeation at rates of less than 0.0001 gm/sq.m/day.