Effects of Pump Pulsation on Membrane Filter Retention
Mark R. Litchy, Donald C. Grant – CT Associates, Inc.
Reto Schoeb – Levitronix GmbH
Hydraulic shocks caused by flow stoppages through microporous membrane filters have been shown to dramatically increase particle release from the filters. The magnitude of the release can be mitigated by techniques like Stabilized Distribution . In Stabilized Distribution, a minimum flow rate is always maintained through system filters to minimize particle release. Changes in the flow rate through a filter have also been shown to affect filtrate particle concentrations .
This experiment was undertaken to determine if pump induced flow pulsations also affect filter performance. Three types of pumps (diaphragm, bellows, and centrifugal) with varying degrees of pulsation were tested at similar average flow rates and backpressures. The magnitudes of the flow pulsations from each pump were measured at all test conditions. Particle retention by two different types of 0.1 ?m membrane filters was also characterized as a function of pump pulsation intensity. Particle retention decreased with increasing pulsation intensity.
CTA publication #58: SCP Global Technologies’ 9th International Symposium on Wafer Cleaning and Surface Preparation, 2005