FGD Gypsum Vacuum Belt Cloth
FGD gypsum vacuum belt cloth is a variant of horizontal vacuum belt filter cloth, specified for flue-gas desulfurization gypsum dewatering.
Machines, duty and industries
Duty
Chemistry, wash and downstream quality questions belong on the application page. This page covers the cloth itself.
Industries
Not sure which belt you need? Tell us your duty →
FGD gypsum vs phosphogypsum
Both are gypsum and both dewater on a horizontal vacuum belt, but they arrive from different processes with different chemistry, so the cloth is specified differently. If you run both, do not assume one spare belt covers the other line.
Weave and polymer are chosen from your duty
Cloth polymer is chosen from your slurry chemistry — pH, temperature and particle size — not from a one-size catalog. In FGD service the chloride level and the wash regime are part of that decision, which is why we ask for them on the RFQ.
We do not publish cake-release, life or throughput figures for a weave. Those depend on the construction finally specified for your duty, and we would rather state that than print a number you cannot hold us to.
- PET monofilament
- PET monofilament + multifilament
- PP (polypropylene)
- DLW / MLW multi-layer weaves
- Special alkali- and hydrolysis-resistant grades
This is the industry-level range for horizontal vacuum belt filters. Our own mill's confirmed weavable polymer list is being confirmed in writing and is not published yet.
FGD Gypsum Belt Parameters
Critical parameters for FGD gypsum dewatering
The parameters below govern cloth selection on flue-gas desulfurization duties — chloride resistance, cake release, and dimensional stability under thermal load. The source tag on each row says whether the reference is imposed by the machine, is a property of the polymer itself, or is a published test method. The full materials reference →
Cloth construction
| Parameter | What it governs | Industry reference | How it is set for your order | What we need from you |
|---|---|---|---|---|
| Polymer Polymer property | The chemical and thermal envelope. Everything else is chosen inside whatever the polymer allows. | PP / PET / PA / PPS / PVDF / PTFE / PE — see the polymer table for the envelope of each. | Chosen from your slurry chemistry and temperature. | Slurry name, pH, temperature, and any cleaning chemistry. |
| Yarn form Polymer property | Cake release, wash-back behaviour and how readily the cloth blinds. | Monofilament / multifilament / mono+multi / staple. | Chosen from particle size distribution and whether release or clarity dominates. | PSD or a d50, and which of the two is hurting you today. |
| Weave Polymer property | The balance between filtrate clarity, permeability and resistance to blinding. | Plain / twill / satin / double layer. | Chosen with the yarn form as one decision, not two. | Same inputs as yarn form. |
Filtration behaviour
| Parameter | What it governs | Industry reference | How it is set for your order | What we need from you |
|---|---|---|---|---|
| Air permeability l/dm²·min or CFM Test method | The headline number everyone compares — how open the cloth is. | Commonly measured per ISO 9237 (at a stated pressure drop, often 200 Pa) or ASTM D737 (Frazier). A value with no stated pressure and no stated unit is not comparable to anything. | Targeted from the duty, then confirmed on the finished lot. | The value and the test pressure for your current cloth, if it is on a datasheet. |
| Cake release behaviour Set per order | Discharge, carry-over, and whether cake releases cleanly without blinding. | Driven by surface finish and yarn form more than by rating. | Tuned through weave, calendering and surface treatment. | Photographs of the discharge point and a description of the carry-over. |
Dimensions
| Parameter | What it governs | Industry reference | How it is set for your order | What we need from you |
|---|---|---|---|---|
| Belt width mm Set by the machine | Fit. A belt that is wrong on width is scrap. | Rubber-belt HVBF machines commonly run to about 4.5–4.8 m. The machine sets it. | Confirmed per enquiry. | Measured width of the old belt, or the machine width. |
| Developed length / circumference mm Set by the machine | Whether the belt tensions correctly on the machine. | Set entirely by your machine and its take-up range. | Confirmed per enquiry. | Developed length of the old belt, measured along the running direction. |
| Dimensional tolerance mm Set per order | Whether the belt tracks. Out-of-square is a tracking fault before it is anything else. | Squareness matters as much as the nominal dimension. | Agreed with the order. | Any tolerance your maintenance standard requires. |
Fabrication
| Parameter | What it governs | Industry reference | How it is set for your order | What we need from you |
|---|---|---|---|---|
| Seam type Set by the machine | Change-out time, vacuum loss at the joint, and where the belt will eventually fail. | Clipper / PAD or welded / spiral / sewn overlap. The machine dictates which. | Matched to what the machine is set up for. | A close-up photograph of the existing joint. |
| Edge treatment Set by the machine | Edge life and vacuum bypass at the seal. | Cut and sealed / hemmed / reinforced band / coated band / guide profile. | Matched to the machine edge seal and to how the last belt failed. | Photographs of both edges of the old cloth and of the machine edge seal. |
Operating envelope
| Parameter | What it governs | Industry reference | How it is set for your order | What we need from you |
|---|---|---|---|---|
| Continuous service temperature °C Polymer property | Which polymers are even candidates. | Approximate continuous figures by polymer: PE ~80, PP ~90, PA ~110, PVDF ~120 continuous (short excursions to ~140), PET ~150, PPS ~190, PTFE ~250. Finish and construction shift these. | The polymer is selected so your duty sits inside its envelope, not at its edge. | Normal and peak slurry temperature. |
| pH range pH Polymer property | Chemical attack, and for PET specifically the hydrolysis risk. | PP and PTFE span effectively the whole scale; PET is limited on the alkaline side, PA on the acid side. | Polymer chosen against your measured pH, including during cleaning. | Operating pH and cleaning pH — they are often different and the cleaning one is often the killer. |
| Chemical exposure Polymer property | Long-term strength loss that does not show up as abrasion. | Specific species matter, not just pH — fluoride, chloride, oxidisers and solvents each behave differently. | Assessed per species, not per industry label. | What is actually in the liquor, including trace species you consider minor. |
Machine interface
| Parameter | What it governs | Industry reference | How it is set for your order | What we need from you |
|---|---|---|---|---|
| Machine family Set by the machine | Everything. The cloth form for one family does not fit another. | Rubber-belt HVBF / vertical tower press / indexing or tray vacuum / drum, disc, leaf, chamber press. | Confirmed before anything else is discussed. | Machine brand and model, or a nameplate photograph. |
| Cloth form Set by the machine | How the cloth is made up — endless belt, zigzag loop, cut panels. | Endless belt for rubber-belt HVBF; endless low-elongation zigzag for tower presses; panels for chamber presses. | Follows the machine family. | Nothing beyond the machine. |
Industry reference — not our mill's confirmed range
| Parameter | Industry reference | Unit | Note |
|---|---|---|---|
| Belt width, common machine range | 4,500 – 4,800 | mm | Upper end seen across the horizontal vacuum belt filter machine family. A machine-family reference, not a statement of what our mill can weave. |
Confirm parameters for your machine →
Filter Cloth Specification Guide
The guide is the long form of the tables above — useful before you write the specification for an FGD gypsum belt, because it explains what each line governs while the values are still open.
Fifteen pages on how a filter cloth specification is built and read: the polymer envelope, yarn form, weave and finish, the four seam constructions drawn out, edge treatments, how to read an air permeability figure, and the full parameter set. It is the methodology edition: every value in it is industry reference — published polymer properties, limits the machines impose, and public test methods. None of it is our mill's own confirmed data, and a parameter edition carrying our values follows when the mill confirms them in writing.
The seam is matched to your existing belt
The seam is matched to the belt you are replacing — clipper, PAD, spiral and overlap are the constructions this machine family runs. Which of them our mill produces in-house is confirmed against your machine during the engineering review. A close-up photo of your current seam is the fastest way for us to quote correctly.
The four filter cloth seam types
Clipper: rows of metal hooks on each cloth end interleave, and a pintle wire passes through the channel they form. PAD or welded: the two cloth ends are skived and overlapped, then thermally fused into one thickness. Spiral: a helical coil is fixed to each cloth end, the two coils mesh, and a pintle wire passes through. Sewn overlap: the two cloth ends overlap and are joined by rows of stitching.
Clipper
Photograph the hook strip and both pin ends.
PAD
Photograph the full joint across the belt width.
Spiral
Photograph the coil and the connecting rod.
Overlap
Photograph the overlap area and both belt edges.
Edge treatment (edge seal and similar) is specified with the seam. The exact seam and edge constructions our mill runs are being confirmed in writing and are not listed here yet.
What is made to order, and what we need from you
Set by your machine
- Belt width and circumference, from measurements off your machine
- Seam type matched to the belt you are replacing
- Edge treatment specified with the seam
- Perforation and drainage pattern, where your old belt has one
Upper limits on width and length are confirmed per RFQ. We would rather confirm your dimension than advertise a range we have not put in writing.
What we need from you
- Machine brand and model — or "unknown"
- Belt width
- Belt length or circumference
- A close-up photo of the seam
- Confirmation that the duty is FGD gypsum
We quote per RFQ. No online checkout.
How this cloth is produced and checked
- 01Materials
- 02Weaving
- 03Heat Setting
- 04Calendering
- 05Cutting
- 06Joint / Seam
- 07Edge Treatment
- 08QC — Air Permeability Testing
- 09QC — Tensile Testing
- 10Inspection
- 11Packing
- 12Export
Air permeability and tensile testing are part of the QC step. The specific test method names, and which steps run in our own mill for each cloth family, are being confirmed in writing and will be published once they are — we do not print a standard number we have not verified. Certificates are supplied as documents on request; we do not run a logo wall.
What goes wrong on a vacuum belt
A failure is not automatically a cloth failure. Root causes split between the cloth, the machine and the process — we will tell you when it is the machine, because a new belt will not fix it.
Asked before a quote
What information do you need to quote a replacement FGD gypsum belt?
Machine brand and model (or "unknown"), belt width and length, a photo of the old cloth and its seam, confirmation that the duty is FGD gypsum rather than phosphogypsum, and what failed. Optional but useful: pH, temperature, chloride level and particle size distribution.
These are the questions a quotation cannot start without. The list will grow as real enquiries come in — it is not padded out in the meantime.
Get a quote for your FGD line
Send the machine brand and model, the belt width and length, a photo of the old cloth and its seam, and what failed.
Not sure about dimensions? Measure your old belt first.
Sample availability, size, freight and lead time are confirmed per request.