Sutnmary. Filtration theory is briefly reviewed with regard to possible application to sterilization by filtration. Of the different devices testecl. Seitz asbestos sheets, acid-treated t,o remove toxic materials, offered most, advantages for routine use and scale-up potential. The standard law of Hermans and Bredhe best expressed mathematically, the filtration of t,issue culture media sterilized by Seitz No. 6 laboratory filters. Data are presented showing the correlation between the performance of the Seitz No. 0 filter, and the Seitz No. 200 plate and frame press (involving a scale-up ratio of up to 400 to 1). An expression: t = 3.26 AP44327/(A/Vf +0.001 AP-0.036) derived from experimental data obtained, expressing time in terms of pressure, surface area, and volume of filtrate, enabled prediction of filtrat,ion parameters with accuracy acceptable for engineering purposes for unclarifietl media, and greatly improved for media which had been initially clarified.
The influence of streaming potent,iril is discussed with regertl to its influence on the course of a filtration.
' depth ' filtration because it has gradient porosity. Surface sealing or clogging of the pad9 is eliminated, resulting in higher rates of flow, fewer pad changes and economy in filtering operations.