Ultra-Low Emission Filter Bag

Request a Custom Quote

Aokai manufactures ultra-low emission filter bags for industrial baghouses operating under increasingly stringent particulate emission requirements.

Our solutions combine application-matched filter media, ePTFE membrane surface filtration, controlled bag construction and accurate bag-to-cage fit. They are designed for projects targeting outlet dust concentrations below 10 mg/Nm³ and, where the complete baghouse system allows, below 5 mg/Nm³.

Available substrates include polyester, acrylic, aramid, PPS, P84, fiberglass and PTFE. Every filter bag can be customized to match the temperature, gas chemistry, dust properties, cleaning method and dimensions of the existing dust collector.

Designed for: Fine and submicron industrial dust
Emission targets: ≤10 mg/Nm³ and ≤5 mg/Nm³
Cleaning systems: Pulse jet, reverse air and mechanical shaker
Custom options: Media, membrane, dimensions, top, bottom, thread and cage fit

Request a Filter Bag Recommendation

What Are Ultra-Low Emission Filter Bag?

Ultra-low emission filter bags are industrial dust collector bags developed for baghouses that need to maintain a very low outlet particulate concentration.

For most projects, “ultra-low emission” refers to a target below 10 mg/Nm³. More demanding plants may require outlet emissions below 5 mg/Nm³.

Compared with conventional needle felt, an ultra-low emission filter bag normally uses a high-efficiency filtration surface, such as an ePTFE membrane filter bags, to prevent fine particles from penetrating deeply into the filter media.

How Aokai Supports Ultra-Low Emission Performance

1. High-Efficiency ePTFE Membrane

Aokai can laminate an ePTFE membrane onto different needle-felt or woven substrates.

The microporous membrane provides surface filtration and helps capture fine particles, including dust that would otherwise penetrate conventional felt. Because most of the dust remains on the surface, the filter cake is generally easier to remove during cleaning.

Potential benefits include:

Improved fine-particle capture
Lower particle penetration into the felt
More consistent emissions after bag replacement
Easier dust-cake release
Reduced risk of deep media blinding
More stable operating differential pressure
Better recovery of valuable process powders

The membrane grade must be selected according to the dust particle size, required permeability, cleaning intensity and mechanical operating conditions.

High-Efficiency ePTFE Membrane

Controlled Filter Bag Construction

2.Controlled Filter Bag Construction

Low-emission performance depends on more than the flat filter media.

Possible dust leakage paths include stitching holes, incomplete seams, damaged bottoms, incorrect snap-band dimensions and poor sealing between the bag and tube sheet.

Aokai controls the filter bag construction according to the application, including:

Consistent seam alignment and stitch density
Sewing thread matched to the filter media
Reinforced top and bottom constructions
Accurate snap-band dimensions
Secure tube-sheet sealing
Correct bag diameter and cage clearance
Reinforcement in high-wear areas
Dimensional inspection before shipment

Additional leakage-control measures can be evaluated for projects with particularly strict emission requirements.

3.Correct Bag-to-Cage Fit

A filter bag that is too tight may be difficult to install and may experience excessive abrasion. A bag that is too loose can fold, rub against the cage and clean unevenly.

For replacement projects, Aokai can match the filter bag and cage using original drawings, an existing bag sample or field measurements.

The evaluation includes:

Filter bag diameter and length
Cage diameter and wire arrangement
Venturi dimensions
Tube-sheet hole diameter
Snap-band groove and thickness
Bag bottom clearance
Cage joint design for long filter bags

Correct Bag-to-Cage Fit

Explore GlassFiber Filter Bags

Technical Specifications of Ultra-Low Emission Filter Bag

Filter media	Typical continuous temperature	Main characteristics
Polyester + ePTFE membrane	Up to 130°C	Cost-effective, good abrasion resistance and suitable for dry conditions
Acrylic + ePTFE membrane	Up to 130°C	Better hydrolysis and mild-acid resistance than standard polyester
Aramid + ePTFE membrane	Up to 204°C	Good heat resistance, strength and dimensional stability
PPS + ePTFE membrane	Up to 160°C	Excellent hydrolysis resistance and good acid and alkali resistance
P84 + ePTFE membrane	Up to 240°C	High-temperature capability and good performance with fine dust
Fiberglass + ePTFE membrane	Up to 260°C	High-temperature resistance and excellent dimensional stability
PTFE felt + ePTFE membrane	Up to 260°C	Broad chemical resistance and high-temperature stability

The specifications above are typical reference values. Final filter media and bag construction are selected according to the operating temperature, gas composition, dust properties, cleaning method and required outlet emission level.

Custom Replacement Filter Bags

Ultra-Low Emission Filter Bag by Industry

Asphalt Mixing Plants

Aramid, P84 and fiberglass membrane filter bags can be used for fine mineral dust at elevated temperatures.

The selection must consider hydrocarbon content, temperature peaks, moisture, acid dew point and abrasion caused by mineral particles.

Cement and Lime Plants

Ultra-low emission filter bags are used in kiln and raw mill systems, clinker coolers, cement mills, coal mills, silos and material transfer points.

Polyester membrane felt may be suitable for low-temperature dust collection. Aramid, P84, fiberglass and PTFE-based co

Waste-to-Energy and Incineration

Incineration flue gas may contain acidic components, fine reaction products, moisture and chemically aggressive compounds.

PPS and PTFE membrane filter bags are commonly considered, depending on the temperature, oxygen concentration and acid-gas treatment process.

Steel and Metallurgical Plants

Potential applications include sintering, electric arc furnaces, blast-furnace dust collection, secondary fume extraction and material handling.

The filter bags must withstand abrasive dust, temperature variation, sparks and intensive pulse cleaning. Anti-static or spark-resistant constructions may also be required.

HELP & SUPPORT

Ultra-Low Emission Filter Bag Technical FAQ

In many industrial projects, ultra-low particulate emission refers to an outlet concentration below 10 mg/Nm³. More demanding applications may specify 5 mg/Nm³ or lower. The applicable limit depends on the industry, country, averaging period, oxygen reference and testing method.

There is no single best material for every application. The substrate must match the temperature and gas chemistry, while an ePTFE membrane is commonly used to improve fine-particle capture. Polyester, acrylic, aramid, PPS, P84, fiberglass and PTFE can all be considered.

No. The filtration surface may use an ePTFE membrane, while the supporting substrate can be polyester, acrylic, aramid, PPS, P84, fiberglass or PTFE. A full PTFE construction is generally reserved for high-temperature or chemically aggressive conditions.

A filter bag supplier should not guarantee a full-scale stack result using filter-media data alone. Filter bags can be designed to support a ≤5 mg/Nm³ target, but the result must be confirmed under actual operating conditions and depends on the entire baghouse system.

A standard membrane bag focuses mainly on the filtration surface. An ultra-low emission solution also considers seams, top sealing, bag dimensions, cage fit, cleaning parameters, leakage paths and the condition of the complete baghouse.

Pulse cleaning removes the dust cake and temporarily changes the filtration condition. Fine dust may pass through conventional media or leakage points during this period. A suitable membrane and controlled bag construction can reduce this risk.

Surface filtration can reduce deep dust penetration and make the dust cake easier to release. This may support more stable differential pressure, but the actual result also depends on filtration velocity, dust properties and cleaning settings.

Request an Instant Quote

*All information will be kept confidential.