Determination of air permeability of a linen material

This article covers a method to estimate air permeability based on a time-dependent transmission of air flow through a sample. There is a large efficiency because of increased signal/noise ratio in the process of estimation, which provides higher accuracy for the technological process (removing contamination). In general case, an estimated parameter of pressure, Up(t), can be expressed as: U_p(t) = ξ(t)·f(t) + η(t), 0 ≤ t ≤ T, where f_p(t) is a function of pressure change in time; ξ(t), η(t) are multiplicative and additive components of error; T is a measurement time period. It is showed here that noise ratio of time-dependent method less than noise ratio of stationary method.