Surface Filtration

Canonical Definition

A filtration mechanism in which particles larger than the surface pore openings of the filter media are captured exclusively at the upstream surface, forming a particle cake layer that itself becomes an increasingly efficient filtration surface as it thickens. Surface filtration provides high initial efficiency at a defined absolute pore size and is characteristic of membrane filters, woven metal screens, and some HEPA-grade media. However, surface filtration results in rapid differential pressure increase as the surface cake builds, and typically has much lower dust holding capacity than depth filtration elements of the same thickness.

Engineering Context

Surface filtration is appropriate for applications requiring absolute filtration — screening all particles above a defined size — but not for high-capacity air or fluid filtration where extended service intervals are required. NANOFORCE technology uses nanofiber surface layers over a depth filtration substrate to provide high-efficiency surface filtration at the fine particle end without sacrificing bulk holding capacity.

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