Mesh Count

The Mesh grade of the mesh/mesh refers to the number of wires per inch and this also influences mesh size (w) and wire strength (d)

Mesh = 25.4mm

w (mm) + d (mm)

Open Area

The open area of a screen (Ao) defines the mesh openings as a percentage of the entire screen surface and is based on the ratio between mesh size (w) and wire diameter (d).

Ao = ( w (mm) )2 x 100%
w (mm) + d (mm)

Mesh CountOpen Area
Absolute Filter RatingFilter rating at 99% efficiency
Nominal Filter RatingFilter rating at 70-90% efficiency
Aperture Distance between wire threads, measured in microns or millimeters
 Pitch Distance from centre to centre of wire threads
 SWG Standard Wire Gauge (Imperial Measurement)
Imperial MeshNumber of apertures counted in a row, see mesh count above
WeftWire threads running down the width of the roll
WarpWire threads running down the length of the roll
Micron1/1000 of a millimetre
Open AreaPercentage of free area in mesh or metal, see illiustration above
BlindingBlockage or restriction of the apertures of a sieve or filter by particles
Differential pressurePressure ratio upstream and downstream from the filter
Dry screeningScreening powdered materials without liquid
Mesh analysisSeparation of a bulk material sample and analysis of particle size
Mesh counterOptical device used to establish mesh count
Mesh finenessNumber of wires per inch (Imperial measure)
Mesh thicknessCalculated according to wire diameter and mesh type
Service lifeOperational life of a screen/mesh until it requires replacement
Square weave meshMesh woven with wires spaced at a distance, giving open apertures
Twilled weaveMesh type giving small filter pores