Abbreviations, Definitions and how to order Screens Sections
w Aperture width
Distance between two adjacents warp or weft wires, measured in the projected plane at mid positions.
d Wire diameter
Diameter of the wire in the woven cloth.
Distance between the middle points of two adjacent wires. Nominally the sum of the aperture width w and the wire diameter d (p=w+d)
All wires running lengthwise in the screen as manufactured.
All wires running crosswise in the screen as manufactured.
Ao Open screening area
Percentage of the surface of all the apertures in the total screening surface. Ratio of the square of the nominal aperture width w and the square of the nominal pitch p = (w+d), rounded to a full percentage value:
Ao = 100 (w : p)²
ρA Mass per unit area
The quantity calculated using the following equitation:
d = wire diameter in mm
w = aperture width in mm
f = type conversion factor (see ISO 4783-1: 1989, table 1)
r = material density in kg per m3 (see ISO 4783-1: 1989,
The equitation gives the calculated mass per unit area in kg/m2 although the actual value can be up to 3% lower.