Filtration & Paper Machine Clothing Glossary
The vocabulary of our trade — forming fabrics, spiral belts, press cloths and dust media — in plain definitions.
- Air permeability (CFM)
- The volume of air (cubic feet per minute) passed by one square foot of fabric at a standard pressure drop. The core specification for dryer and filter fabrics.
- Anti-hydrolysis yarn
- Polyester monofilament stabilised against hot-water attack — standard for humid forming sections and FGD duties.
- Anti-static yarn
- Conductive (usually carbon-cored) filament woven into the fabric to drain static charges on high-speed dryers.
- Belt press filter
- A continuous filter that squeezes sludge between two moving belts through gravity, wedge and pressing zones.
- Bullnose joint
- A PTFE belt joint where folded, rounded belt ends overlap — quick to fit and re-lace.
- CFM
- See Air permeability. Typical spiral dryer fabrics reach ~900 CFM; filled press belts run 20–150 CFM.
- Clipper seam
- A metal clip (wire hook) seam joining belt ends — strong and repairable.
- Disc filter
- A rotary vacuum filter with segmented discs covered by filter fabric sectors.
- Dryer fabric
- The fabric carrying paper/board/food through heated dryer sections; also called dryer belt.
- FGD
- Flue gas desulfurization — its gypsum by-product is dewatered on vacuum belt filters.
- Filler yarns
- Extra monofilaments inserted into spiral belt loops to raise density and lower permeability (1–5 yarns; round or flat section).
- Filter press cloth
- Fabric (monofilament, multifilament, staple or combinations) cut and sewn for chamber / membrane filter plates.
- Forming fabric
- The wet-end belt that forms and dewaters the fiber web; historically called forming wire (from the bronze-wire era).
- Forming wire
- Trade name for a forming fabric — still standard among machine crews and in B2B listings.
- Fourdrinier
- The classic flat-wire paper machine; the forming section is still often called the wire section.
- Horizontal vacuum belt filter (HVBF)
- A continuously indexing or endless-belt vacuum filter for dewatering and washing duties.
- Mesh count
- The number of openings per centimetre (or per inch) of a woven mesh — higher count, finer opening.
- Monofilament
- A single smooth yarn — best cake release and blinding resistance in filter cloths.
- Multifilament
- A yarn twisted from many filaments — finer retention, clearer filtrate, harder cake release.
- Open area
- The percentage of fabric surface that is opening; high open area = high flow.
- Paper machine clothing (PMC)
- The umbrella term for forming, press and dryer fabrics on a paper machine.
- Pin seam
- A joint where a pin (or clipper wire) runs through loops formed in the belt ends.
- PPS
- Polyphenylene sulphide — a monofilament/felt polymer for hot, chemical duty (~240 °C long-term in spiral fabrics).
- PTFE
- Polytetrafluoroethylene — non-stick, food-grade, 260 °C; used as belt coating and membrane material.
- Scarfed joint
- A PTFE belt joint planed to a taper so the overlap stays near belt thickness — smooth over rollers.
- Screen mesh / sifter mesh
- Woven mesh fitted as the working surface of a vibrating, gyratory or circular sifter.
- Spiral dryer fabric
- Spiral-link belt without filler yarns — open structure (up to ~900 CFM) for drying and conveying.
- Spiral press filter belt
- Spiral-link belt with 1–5 filler yarns — dense, low-permeability filter belt for belt press filters.
- SSB (triple layer)
- Sheet-side / machine-side triple-layer forming fabric construction for quality paper grades.
- Square weave mesh
- Plain-weave (1/1) mesh with precise square openings, e.g. 40–200 mesh count polyester.
- Tube sheet
- The perforated plate of a baghouse that filter bags hang from — bags are sized to it.
- Vacuum filter fabric
- Fabric for vacuum belt, disc and drum filters, in PET / PP / PVDF.
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