Filtration & Paper Machine Clothing Glossary

Key Technical Terms (A–Z)

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 stabilized 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 press filter 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 dryer fabric carrying paper, board or food through heated dryer sections; also called dryer belt.

FGD

Flue gas desulfurization in power plants — 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

Press filter fabric (monofilament, multifilament, staple or combinations) cut and sewn for chamber and membrane filter plates.

Forming fabric

The wet-end forming fabric 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 sulfide — 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) polyester square mesh with precise square openings, e.g. 40–200 mesh count.

Tube sheet

The perforated plate of a baghouse that filter bags hang from — bags are sized to it.

Vacuum filter fabric

Vacuum filter fabric for vacuum belt, disc and drum filters, in PET, PP and PVDF.