| 摘要 |
The present invention provides a method and apparatus for evaluating the porosity of a sheet material at a given value of gas flow or pressure drop (PD), with account being taken of the following relationship between the parameters of flow and PD: Flow=A (PD)N, in which one of the parameters is set at a number (e.g. 3) of values close to the said required value, the other parameter is measured at each, the values of A and N for the sample under test are calculated therefrom, and then the precise gas flow (or PD) at the given PD (or gas flow), and hence the porosity, is calculated from the said relationship. The automatic setting, and the calculations, are effected by means of a microprocessor.
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