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).


Good Manufacturing Practices. Food and Drug Administration regulations governing the manufacture of drugs and medical devices (Ref. Code of Federal Regulations 21CFR).


There are two different types of half-tone:
Amplitude modulated rastering (AM): Resolution in a constant number of dots per area, the dot sizes are variable.
Frequency modulated rastering (FM): The dots are as small as possible but the size is constant. The number of dots per area is variable.

Half-tone printing

Printing of in halftone dots converted continuous-tone images, consisting of individual raster dots.


Having an affinity for water and aqueous solutions.


Cannot be wetted by aqueous and other high surface tension fluids.

Ink release

Release of the ink from the stencil

Ink volume, ink deposit dry

Ink deposit after drying respectively hardening of the ink in mm

Knit fabric

A fabric structure made by interlooping yarns, a type of knitted fabric

Loaded (plugged)

A filter element that has collected a sufficient quantity of insoluble contaminants such that it can no longer pass its normal-rated flow without excessive differential pressure.

Icon Backward


Icon Forward


Sefar AG

Hinterbissaustrasse 12
9410 Heiden

Telefono +41 71 898 5700

Fax +41 71 898 5721

Invia mail

Filtrazione e Separazione