An ePTFE laminate is a membrane thin enough to be measured in micrometres, bonded to a felt thick enough to hold a bag’s shape. The datasheet is short, and most arguments about performance come down to how three of its lines are read.
Ningbo ChaoYue technical team, cy-ptfe.com·Published 2026-11-11·Last verified: 2026-11-11·Checked against our published membrane data
TL;DR
- An ePTFE laminate is a microporous PTFE membrane, 3 to 7 micrometres thick in our published rows, bonded to a needle felt that carries the strength.
- The membrane filters on the surface, so dust releases as a cake instead of embedding in the felt, and residual pressure drop stays lower for longer.
- Our three published rows run 35 to 120 L/m²·s at 3 to 7 micrometres, in rolls up to 3,500 mm wide, with efficiency above 99.5% to 99.9%.
- Permeability and efficiency pull against each other, so choosing a row is a pressure-drop decision before it is an efficiency decision.
- Most failures happen after the roll is delivered: creases, needle holes at seams, adhesive strike-through and over-aggressive pulse cleaning.
An ePTFE laminate for baghouse service is a surface filter, not a depth filter, and that single fact explains the specification sheet. A depth filter traps dust inside its structure and has to be cleaned by pulling it back out; a membrane keeps the dust on a thin, non-stick surface where a pulse of air can lift it off. Everything that follows, from permeability to bag life, is a consequence of that choice.
We make the membrane rather than the bag, so the questions that reach us are usually about the roll: which row matches a given dust, what a permeability figure really compares, and why the bag maker needs a width that leaves a sensible cutting plan. We work through the datasheet in that order.
What is an ePTFE laminate, layer by layer?
An ePTFE laminate has three layers: a microporous PTFE membrane, a support felt, and the bond between them. The membrane is made from PTFE resin by paste extrusion, then stretched in two directions and sintered, which produces the node-and-fibril structure visible under magnification and the controlled porosity that makes the material a filter rather than a film.
We control pore size, pore size distribution and open area in that process, so resistance and efficiency can be adjusted against each other. The membrane is chemically inert, hydrophobic, and 3 to 7 micrometres thick in our published rows.
In our range the support felt is needled polyester, PPS, Nomex, polypropylene or glass fibre, and it does a different job. It provides tensile and burst strength, the body a bag or pleat needs, and most of the temperature and chemical resistance of the finished media. We laminate to all of those felts, and the choice is usually made before the membrane grade is discussed.
The membrane decides what gets captured, and the felt decides whether the bag survives; confusing the two is the root of most specification arguments. We see buyers ask for a higher efficiency membrane to solve a temperature problem, which buys the wrong part, and upgrade the felt to solve blinding, which does the same.
What do the three published rows actually tell you?
We publish a table short enough to read line by line, and each line changes something different in the baghouse. Width changes the cutting plan, permeability changes the clean pressure drop, thickness changes handling, and the efficiency figure changes what passes through at the start of a filter’s life.
| Item | Width | Air permeability | Thickness | Efficiency |
|---|---|---|---|---|
| H12B | 2,600 mm to 3,500 mm | 90 to 110 L/m²·s | 3 to 5 µm | Above 99.7% |
| D42B | 2,600 mm | 35 to 40 L/m²·s | 5 to 7 µm | Above 99.9% |
| D43B | 2,600 mm | 90 to 120 L/m²·s | 3 to 5 µm | Above 99.5% |
The two numbers that move together are thickness and permeability: the 5 to 7 micrometre row carries 35 to 40 L/m²·s, while the 3 to 5 micrometre rows carry 90 to 120 L/m²·s. That is no coincidence, and we see the same pattern in every batch we laminate. A thicker membrane puts more material in the air path, so it resists flow more and captures more of the fine fraction. The tight row suits fine dust where the emission limit binds; the open rows suit installations with fan pressure to spare and bag life that depends on cleaning energy.
In our experience width is easy to miss in a specification review. A 2,600 mm roll and a 3,500 mm roll give different panel counts per metre and different offcut, which changes the material cost per bag and the number of splices the bag maker works around. On a fixed bag length the roll width is a conversion decision, so it belongs in the conversation with the bag maker.
Why do permeability and efficiency pull in opposite directions?
We measure permeability as how easily air passes through the media, and efficiency as how much dust it stops; for a given membrane structure, improving one costs the other. A membrane with larger openings passes more air at the same pressure and lets more fine particles through. A tighter membrane stops more and resists more.
We publish the unit as litres per square metre per second at a stated pressure difference, so a permeability figure only compares fairly when the test pressure and sample area are the same. That is why we quote a range for a row, and why an incoming test belongs against the certificate for that batch rather than against another supplier’s datasheet.
Because the membrane keeps the dust on the surface instead of inside the felt, the cleaning pulse has less material to move, and the residual pressure drop stays lower between cycles. We see that as the real prize of a laminated media: not the clean pressure drop on installation day, but the pressure drop six months later, which decides whether the fan has margin and whether the bags flex hard enough to wear at the seam.
We also see surface filtration change the air-to-cloth ratio a baghouse can run, because dust held on a surface that releases it lets a designer specify a higher ratio for the same pressure drop. We do not publish a ratio recommendation, since it depends on the dust, the cleaning system and the inlet loading.
What do H11, H12 and H13 actually classify?
H11, H12 and H13 are efficiency classes from the high-efficiency filter standards, not grades invented by a membrane supplier. In Europe the reference is EN 1822, and the international equivalent is the ISO 29463 series, which classifies high efficiency filters and filter media for removing particles from air. The classes we quote are defined by penetration at the most penetrating particle size, which sits below one micrometre.
We quote the usual thresholds as 95% for H11, 99.5% for H12 and 99.95% for H13, measured against a defined aerosol and test method. Our published rows show minimums of 99.5%, 99.7% and 99.9%, and the range is described as reaching H11 to H13. Which class a roll is certified to depends on the test, the sample and the standard edition, so we put it in the quotation rather than infer it from a model code.
Because the class is awarded to a filter or a media sample against a defined aerosol, it does not translate directly into a stack emission figure. A baghouse emission depends on the seams, the cage fit, the tube sheet and the cleaning strategy as much as on the media. A high class narrows the starting point; it does not guarantee the outlet.
Which support felt does the membrane need?
The support felt, not the membrane, usually sets the temperature and chemical limit of an ePTFE laminate. PTFE is inert and normally quoted for continuous service near 260 °C, while the felt underneath is an organic fibre with a lower limit and its own chemistry.
In our range polyester is the general-purpose choice, and the one to avoid in moist hot gas, where hydrolysis attacks it below its dry rating. PPS handles acids and suits coal and municipal waste gas, but it is vulnerable to oxidation and to high nitrogen oxide levels. Nomex sits between the two on temperature, and glass fibre is the high-temperature option at the cost of brittleness and flex life. We laminate to PP felt, polyester, PPS, Nomex and glass fibre needle felt.
Because the membrane is inert, a laminate that fails by temperature almost always fails at the felt, and the symptom is a bag that goes brittle rather than a membrane that stops filtering. When a project sends us a failed bag, the first question is what the felt is and what the gas does to it, not what the membrane grade was.
Where does the laminate get damaged between the roll and the baghouse?
Most laminate failures we see are mechanical and happen after the roll leaves us: a crease that breaks the membrane, a needle hole at a seam, adhesive that has struck through the felt, or a cage that rubs during cleaning. The membrane is thin, and it does not heal.
We treat creasing as the quiet one, because a creased roll can look perfect and carry a line of broken fibrils that only shows under light. Seam sewing is the obvious one, since every needle makes a hole through the filtering layer. Adhesive strike-through hides in the permeability figure, because a bond that has bled into the felt reduces flow without visible damage.
Because a pulse-jet baghouse flexes its bags millions of times, the media has to survive movement as well as chemistry. Cleaning above the pressure the bag and cage were designed for accelerates wear at the seam and the cage contacts, and the first sign is usually emissions rather than pressure drop.
What should an incoming inspection check?
Four checks catch almost every laminate problem before the roll reaches the bag line: width and splices, permeability against the certificate, a light test for pinholes, and the bond at the edge. None needs a laboratory, and all need a sample from the roll rather than a datasheet.
- Check the roll against the order, measuring the width and recording the splices, because a splice in the wrong place changes the cutting plan for every bag.
- Take a permeability sample from the outer wrap and compare it with the certificate value for that batch, using the same test method and sample area.
- Inspect the membrane against a light for pinholes, creases and thin patches, since a crease that has broken the membrane will not seal in service.
- Check the bond at the edge for lift and for adhesive strike-through into the felt, which reduces permeability and can stain the first bag run.
We test air permeability to ASTM D737, the standard test method for air permeability of textile fabrics, and characterise pore size by bubble point under ASTM F316, the standard test methods for pore size characteristics of membrane filters. Quoting those methods on the purchase order removes most of the argument about whose number is right.
What belongs in the baghouse media inquiry?
We can answer a media inquiry that carries six facts: gas temperature, gas chemistry, inlet dust loading, target emission, bag or pleat dimensions, and the cleaning method. Everything else, including the membrane row, follows from those.
We let temperature and chemistry decide the felt before the membrane is discussed, and dust loading with the target emission decides whether the open rows or the tight row make sense. Bag dimensions then fix the roll width, and the cleaning method decides how much flex the media will see.
Our ePTFE air filter membrane range carries the published rows this page works from, and the H11 to H13 laminate detail sits in our note on membrane efficiency and laminate specifications for baghouse OEMs. For a specific dust, send the six answers and we will confirm the row, the felt and the roll width rather than leaving the choice to a catalogue code.
Frequently asked questions
How thick is an ePTFE membrane used in baghouse filter media?
Can ePTFE be laminated to polyester needle felt?
Does a higher H class mean lower baghouse emissions?
How should a roll of laminate be checked on arrival?
What temperature can an ePTFE laminate run at?
Send the six answers and we will match the row
Gas temperature, chemistry, dust loading, target emission, bag dimensions and cleaning method. With those we can confirm the membrane row, the felt and the roll width, and quote the volume you need.
Related reading: ePTFE air filter membrane range · H11 to H13 laminate specifications for baghouse OEMs · high-efficiency ePTFE filter membrane · baghouse media inquiries
Post time: Nov-12-2026