Patent ID: 7174770

Claim:
Method for automatic determination of the permeability of a sheet or a strip of porous material consisting of successive segments which present different levels of permeability, alternately and with a pre-establishing periodicity T, where this method implements a permeability meter consisting of a measuring head in relation to which the said sheet or strip can be moved in steps, said method comprising: a preliminary positioning stage, with determination of a permeability profile of the sheet or strip over a length of material corresponding to at least the period T, which comprises two successive segments, determination of a sinusoid from the profile obtained, determination of the position of the two ends of this sinusoid, and centring of the measuring head at the second end, and a measurement stage following centring of the head, consisting of the advance, step by step, of the sheet or strip in steps of T/2, with a permeability measurement at each step.