PT  - JOURNAL ARTICLE
AU  - Lukaszewicz, Raymond C.
AU  - Johnston, Peter R.
AU  - Meltzer, Theodore H.
TI  - Prefilters/Final Filters: A Matter of Particle/Pore Size-Distributions
DP  - 1981 Jan 01
TA  - PDA Journal of Pharmaceutical Science and Technology
PG  - 40--47
VI  - 35
IP  - 1
4099  - http://journal.pda.org/content/35/1/40.short
4100  - http://journal.pda.org/content/35/1/40.full
SO  - PDA J Pharm Sci Technol1981 Jan 01; 35
AB  - A filter functions as a prefilter or final filter depending upon its pore-size distribution relative to the size distribution of the challenging particles. In prefiltrations, the pore-size distribution relative to the particle-size distribution is wide, thus inviting particle invasion of the pores whereby extensive adsorptive arrests can be accommodated upon the filter’s large internal surfaces. The capture reliability of particles small enough to enter pores reflects such operational considerations as particle population and applied differential pressure. Prefilters only serve to reduce the ultimate particle load of the final filters. The final filter serves to arrest particles with as efficiently as possible by the surface retentivity of large-particle/smallpore-size relationships. Such sieve-type capture is absolute, i.e., it is independent of operational conditions. Because relatively limited surface depositions may compromise final filter throughput, such filters require the particulate-removal protection of prefilters. The broad pore-size distributions of prefilters, usually depth-type, result from their manufacture technology. The relatively narrow pore-size distributions of final filters, usually membranes, result from their mode of manufacture.