With the pressure step/stability method an inlet valve for the gas is a large needle valve which opens with very accurate and precise movements. To increase pressure, the valve opens to a precise point and then stops its movement. A datapoint is recorded when the used defined stability algorithms are met for both pressure and flow. In this way, the porometer detects the opening of a pore at a certain pressure and waits until all pores of the same diameter are completely opened before accepting a data point. This results in very accurate measurement of pore sizes and allows a calculation of the real pore size distribution from simple to very complex filters and membranes.

This method also allows the measurements of smaller pores, down to 13 nm, as higher pressures can be obtained using this methodology.

A complete overview of the POROLUX^TM 1000 series can be found in the instrument section.