Pore Size Distribution

Pore size distribution (PSD) characterises the range and frequency of pore diameters in a porous medium. Rather than quoting a single micron value, PSD explains how retention and permeability vary across the structure. The largest pores determine bubble point and breakthrough risk, the mid-range (mean-flow pore size, MFPS) dictates flux, and the fine tail affects fouling and depth capture. Capillary-flow porometry and mercury intrusion are standard methods to assess PSD. A narrow, well-centred distribution ensures consistent filtration and cleanability; a broad distribution yields higher initial flux but uneven retention. Specifications should always include bubble point, MFPS, and a graphical pore-size curve, as well as acceptance limits for variation after defined operating cycles.