The aim in process filtrations is to purify the liquid preparation by removing particulate impurities while obtaining as large a throughput as possible under practical conditions. The rate of flow should be expeditious enough to meet time constraints when necessary. This places a focus on the applied differential pressure level that motivates the liquid flow. A balance must be sought. Higher differential pressures increase the flow rates but may decrease throughputs by compaction of the filter cake. Also, higher applied pressures may minimize the adsorptive retention of particles. Deciding which is the proper filter involves small-scale filtration trials. The choice of the filter having been made, its size, in terms of the area necessary for the processing of the production batch, is arrived at by extrapolations from the small-scale tests that were performed…
Tag: <span>filtration</span>
The Vmax™ technique has been used extensively to estimate filter area requirements for normal flow filtration (NFF) processes in biopharmaceutical applications. The benefits that this technique presents over conventional flow decay methods are the speed of testing, reduced volume requirements for evaluation, and competitive testing of varying filter types/sizes — all of which present an optimized filter screening strategy and preliminary estimate of optimized filter size requirements. Filter size or filtration area requirements derived using the Vmax technique consist of contributions from both capacity and flow-time aspects of the filtration process. This article examines the relative contributions of these terms to overall filter sizing vis-à-vis the ease of fluid filterability…