Principles of Filtration
December 10, 2020
Filtration is a science of growing information, distinctive terminology, and proprietary knowledge. These basic concepts have been compiled so that we, Pall Medical, can establish a common ground with you, our customer, on the basic language of filtration. Over the next few blogs, we will explain some of the fundamental aspects of filtration technology and how they relate to each other and to your application. Then, we will guide you through the logic of selecting a filter media for specific market applications in each market application section. As always, if you have questions about any of these concepts or how they apply to your specific application, please contact us.
Filtration is a process by which particles are removed from a fluid (whether liquid or gas) as it passes through a permeable material. There are various types of filtration including but not limited to conventional dead-end filtration, depth filtration, tangential flow filtration, and ultrafiltration.
Filtration media have many different properties that impact its performance in certain applications. When selecting the best filter media for your application, consider the following important properties:
- Depth vs. Membrane Filtration
- Filter Efficiency
- Hydrophilic vs. Hydrophobic
- Pore size rating
- Chemical Compatibility
- Flow rate and throughput
- Thermal Stability
Depth vs. Membrane Filtration
A Depth Filter consists of either multiple layers or a single layer of a medium having depth - which captures contaminants within its structure opposed to on the surface.
- Protects final filters (pre-filter)
- High throughputs
- High particulate loading
A Membrane Filter typically traps contaminants larger than the pore size on the addressed surface of the membrane. Contaminants smaller than the rated pore size may pass through the membrane or may be captured within the membrane by other mechanisms. Membrane filters are typically used for critical applications such as sterilizing and final filtration.
- Absolute sub-micron pore size ratings possible
- Bacteria and particle retentive (pore size dependent)
- Generally lower extractables
Jacques Hestres, Product Manager for Media – Membrane at Pall Corporation
Joseph Vickers - Portfolio Lead, Membrane & Media
Antoine Pozniak - Product Manager Media - Membrane at Pall Corporation
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