| abstract |
A process for measuring the gas permeability of a film (10) or other thin materials, comprising the following operative steps: dividing by means of said film (10) the interior of a tank (4) into a load chamber (5) and a measure chamber (6), whereby said chambers (5, 6) are not in fluid contact with each other; lowering the pressure in the load chamber (5) down to a value of less than 0,1 mbar and the pressure in the measure chamber (6) down to a value of less than 10-6 mbar; continuously evacuating the measure chamber (6) by means of a high-vacuum pump (18) connected to said chamber (6) through a duct (17) provided with a choking neck (22) having a known conductance C; introducing a gas into the load chamber (5); continuously measuring in the duct (17), upstream of the neck (22), the partial pressure of said gas as long as a constant pressure value P¿2? is determined; measuring the pressure P1 inside the load chamber (5); and calculating the permeability X of the film (10) as a function of P1, P2 and C. An apparatus that carries out this process is also described. |