Fiberglass filter bag provides dimensional stability at high temperature; however, it is sensitive to fragility, cage surface, installation, and packaging errors.
What Is Fiberglass Filter Bag?
Fiberglass filter bags are a bag family considered for high-temperature applications, offering strong dimensional stability but mechanically fragile. Versions reinforced with PTFE coating or membrane can be used in heavier-duty processes.
High-Temperature Advantage and Mechanical Risk
The fiberglass family can be a candidate for some applications in the 240-260°C range; short peaks are verified against the media construction and manufacturer datasheet. However, the fiber structure is brittle: a burred cage, incorrect installation, heavy stacking, sharp bending, and high pulse pressure can lead to early bag failure.
Areas of Use
| Sector | Process | Control |
|---|---|---|
| Cement/ lime/gypsum | Hot gas, clinker environment | Wear and cage |
| Asphalt | Hot mineral/powder | Oil/acid/moisture |
| Casting/metal | Hot smoke/dust | Spark and impact |
| Energy/boiler | High temperature | Chemical gases |
Cage, Pulse, and Packaging
For a fiberglass bag, the cage surface is very critical. A smooth weld, correct wire count, correct outer diameter, venturi fit, and a taut bag-on-cage seating are required. For sea shipment, moisture-protected packaging and special protection against crushing and sharp bending should be requested.
When Should I Choose Fiberglass?
Example
Example
- Process
- Lime hot gas filter
- Heat
- 240°C
- Symptom
- Localized tear in the old bag
- Control
- Cage burrs and pulse pressure
Information for Bid
For a fiberglass bag, we need the temperature, gas chemistry, dust abrasiveness, cage photos, pulse pressure, bag dimensions, packaging/shipping conditions, and any existing damage images. You can share this data through the quote form. For a detailed high-temperature version, see the fiberglass PTFE guide.
Frequently Asked Questions
Why Does a Fiberglass Bag Break?
A burred cage, rough installation, crushing, excessive pulse pressure, or improper packaging can cause fiber breakage.
Is a Fiberglass Bag Suitable for Every High Temperature?
No. Besides temperature, chemistry, moisture, cage, and mechanical conditions must also be confirmed.
Engineering Selection Parameters: Media Name Alone Is Not Enough
When selecting a filter bag, the media name is only a starting point. The same fiberglass filter bag can run stably under a low A/C ratio, dry dust, and a properly functioning pulse system, but under high airflow, a damp cake, a poor cage, or an incorrect snap-band size, it can develop a dP or emission problem within a short time. That is why, in Hantech's evaluation, the bag is read together with the fan, filter area, cage, cell plate, pulse valve, and hopper behavior.
| Parameter | - why it is critical | Data requested for the quote |
|---|---|---|
| Normal / peak temperature | Media aging, shrinkage, and seam strength | Shift records, alarm history |
| Moisture and dew point | Sticky cake, hydrolysis, or chemical aging | Gas moisture, insulation, start-stop behavior |
| Gas chemistry | SOx/SO3, NOx/NO2, HCl, HF, O2, and an alkaline environment change media life | Gas analysis or process recipe |
| Powder micron distribution | 1-3 µm dust embeds into the felt; coarse abrasive dust wears down the housing | Particle analysis or site observation |
| A/C ratio | High filtration velocity causes rising dP and short bag life | Flow rate, bag diameter-length-count |
| dP trend | Indicates blinding, leaks, or inadequate cleaning | Pa/mmWG chart after new bags |
| Cage outer diameter and surface | Incorrect OD, burrs, or rust mechanically abrade the bag | Cage photo, OD, wire count |
| Snap-band / cell plate | Mouth leakage produces low dP + high emissions | Hole diameter, sheet thickness, bead detail |
This approach is especially important for fiberglass filter bag, because in the field the problem often appears to be 'bad media,' but the root cause may be the A/C ratio, pulse energy, moisture, cage surface, or cuff sealing.
Which Field Symptom Changes Which Decision?
| Site indication | Possible root cause | Hantech approach |
|---|---|---|
| dP rises above 1800-2200 Pa after new bags | High A/C, fine dust penetration, moist cake, or weak pulsing | Surface treatment/membrane need and filter area are checked together |
| Low dP but dust at the stack | Filter bag tear, snap-band leakage, or bypass | Cell plate, collar detail, and cage contact marks are checked |
| Vertical wear on the filter bag body | Cage burrs, incorrect OD, or bag chafing | Bag performance cannot be upgraded without replacing the cage surface and wires/rings |
| Dust traces at the filter bag top | Snap-band isn't seating properly, or sheet thickness is wrong | Double cord, band size, and hole tolerance are re-measured |
| dP increases on humid days | Dew point, condensation, or sticky cake | Thermal insulation, hydrophobic surface, and process control are evaluated together |
This table is used at the quoting stage to avoid selling the customer an unnecessary premium media. If the symptom stems from a mechanical or process issue, choosing a more expensive bag will not be a lasting solution.
Comparison with Alternative Media
Fiberglass is compared with the PTFE-coated/membrane version, P84, and Aramid in terms of temperature, chemistry, and mechanical risk. Hantech's approach is not to impose a single brand or the most expensive option, but to balance the most economical, safe solution that is sufficient against the process risk.
| Comparison criterion | Comment for this media | Alternative decision |
|---|---|---|
| Heat | The 240-260°C range may be feasible; the construction and PTFE treatment are the deciding factors. | If the limit is exceeded, a higher-grade media is considered |
| Fine dust / low emission | A need for surface treatment or a membrane can arise | ePTFE membrane, P84, or PTFE is compared |
| Moisture / acid | Media chemical resistance is not read on its own -- it's assessed together with dew point | Options such as PPS/PTFE/fiberglass PTFE may be required |
| Mechanical risk | Cage and installation errors can ruin even good filter media | The cage/snap-band/pulse system is corrected first |
| Expense | Premium media is selected only when there is a real risk or target | Adequate candidates such as PES/PPS/Aramid are not ruled out |
Under These Conditions, I Would Not Choose Fiberglass Filter Bag
Worked Example: Fiberglass Selection for a Lime Hot Gas Filter
Sample account and comment
- Flow Rate
- 60,000 m³/h
- Bag size
- Ø160 x 6,000 mm
- Number OF bags
- 240
- One bag area
- π x 0.16 x 6.0 = 3.02 m²
- Total Area
- 240 x 3.02 = 724.8 m²
- Gross A/C
- 60,000 / 60 / 724.8 = 1.38 m/min
- First decision
- Fiberglass filter bags are evaluated based on dust particle size, moisture, and dP trend
This example value is not good or bad on its own. 1.38 m/min may look acceptable for dry, medium-grain mineral dust, but risky for fine (1-3 µm), sticky, or moist dust. If dP rises quickly after a new bag is installed, the surface finish, pulse energy, filter area, and inlet distribution should be reviewed together, not just the media.
Fiberglass offers dimensional stability at high temperature, but because of its brittleness, the cage, pulse setting, and packaging become critical. However, this selection should not be turned into a final quotation until the cage surface and snap-band fit are verified.
RFQ / Quotation Checklist
Size and quantity alone are not enough for a sound fiberglass filter bag quote. The minimum data set is: bag diameter, bag length, quantity, top attachment type, bottom cap detail, current media and weight, surface treatment, normal/peak temperature, moisture or dew point risk, gas chemistry, dust type, micron distribution, dP trend, target emission, cage outer diameter, cell plate hole size, sheet thickness, pulse pressure, and photos of the current bag/cage.
Once this information is available, Hantech evaluates filter bags, filter cages, pulse-jet valves, and if needed performance measurement together. You can submit the data via the quote form.
Technical Review Note
Technical review: Doğuhan Kırmacı — industrial filtration, dust collection systems and filter bag selection applications.
This content has been prepared by comparing process data, manufacturer technical limits, field failure behavior, and bag-cage-pulse compatibility. The values here are for preliminary selection; the final selection must be verified against the manufacturer's datasheet, site measurements, and process conditions.