For multi-layer filter packs, Extruder screen pack convention defines the specification designations and tolerances. The sections below describe the scope, the properties it leaves to companion standards, and the equivalent designations across standards bodies.
Extruder screen pack convention — Scope
Extruder screen pack convention specifies the designation system, dimensions and tolerances of multi-layer filter packs — mesh count or nominal opening, wire diameter and the permissible aperture deviations. Alloy chemistry, mechanical testing and delivery condition are governed by separate documents in the same standards family.
Tolerance Classes
Extruder screen pack convention defines tolerance limits on the average aperture and on the maximum single aperture, tightening as the aperture gets finer. For test-sieve duty the tighter ISO 3310-1 tolerances apply instead of the general cloth tolerances — specify sieve grade explicitly if the mesh will be used for particle-size analysis.
Specifications Defined by Extruder screen pack convention
| Diameter (mm) | Mesh / micron options | Layers | Edge treatment | Reference standard |
|---|---|---|---|---|
| 20 | Coarse guard + fine + support | 3 | Spot welded | Extruder / SPM pack |
| 38 | Coarse guard + fine + support | 3-5 | Spot welded | Extruder / SPM pack |
| 50 | Coarse guard + fine + support | 3-5 | Bound rim | Extruder / SPM pack |
| 90 | Coarse guard + fine + support | 5-7 | Bound rim | Extruder / SPM pack |
| 155 | Coarse guard + fine + support | 5-7 | Bound rim | Extruder / SPM pack |
Companion Standards
Extruder screen pack convention controls the geometry of multi-layer filter packs. Companions frequently cited alongside it: ISO 565 / ASTM E11 (test-sieve aperture series), ISO 3310-1 (test sieves of metal wire cloth), ISO 4783 (selection of wire and aperture combinations), ISO 9044 (industrial woven wire cloth), and ISO 2941 (collapse/burst rating for finished filter elements).
When to Specify Extruder screen pack convention
Choose Extruder screen pack convention for international procurement and OEM supply where ISO documents are the contractual reference. It is the default modern specification for multi-layer filter packs.