Abstract
In reverse-flow cleaning of cakes deposited on porous filters, the pressure drop induced across the cake at the point of its detachment is the cleaning stress, ie the tensile stress which must be applied to overcome adhesion of the cake to the medium or the cohesion of the cake itself. A thicker cake requires a smaller pressure gradient for removal and therefore less cleaning gas flow and less pressure drop through the medium itself. Provided that true surface filtration occurs, the cleaning stress should be independent of cake areal mass. J. Sievert and F. Loeffler's data for a singed polyester needlefelt suggests that this is indeed so, and that the cleaning stresses induced by reverse-flow cleaning are close to those required if the filter is cleaned by mechanically-induced acceleration.