Fabric geometry

See mesh geometry

Farady cage

A cage made of conductive material. Static fields and discharges do not pass through it. Electromagnetic energy passing through the skin or shield is attenuated to varying degrees.


The material entering a filter processing unit for treatment.

Filter cake

The solids discharged from a dewatering apparatus.

Filter life

Measure of the duration of a filter’s useful service. This is based on the amount of standard contaminant required to cause differential pressure to increase to an unacceptable level – typically 2 – 4 times the initial differential pressure, a 50 – 80% drop in initial flow, or an unacceptable downstream amount of particulate matter.

Filter media

A porous material for separating suspended particulate matter from fluid.

Filter medium

The permeable portion of a filtration system that provides liquid/solid separation, such as screens, papers, non-wovens, granular beds and other porous media.


The discharge liquor in filtration.


A process of separating particulate matter from a fluid by passing it through a permeable material.

Flow rate

Measure of the amount of fluid passing through the filter. This is always a variable depending on filter area, porosity, contamination and differential pressure.


The purpose of the frame is to hold the tensioned screen printing mesh. It has to be stable enough not to be deformed by the big forces of the highly stretched mesh and the printing process.

Frame section

Beside the material (steel, aluminium), the profile and the cross section are crucial for the dimensional stability of screen printing frames. We distinguish between square- rectangular - and special sections.

Frazier test

Measures the amount of air transmitted through a filter under selected differential pressures. Historically used for textile products. See Air flow.


Number of cycles of current per second, expressed in Hertz (Hz).


Sefar AG

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9410 Heiden

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Filtration & Separation

Screen Printing