Cotton Bag Filter
Economical Filtration for Particles and Free Oil in Liquids and for Dry Dust
The cotton bag filter is a natural-fibre filter that helps retain solids and free oil in liquids and provides general-purpose filtration in low- and medium-temperature dust collection systems.
Natural Cotton
90 °C (Liquid) / 82 °C (Dust)
2–2.5 bar
What Is a Cotton Bag Filter?
Cotton bag filters are a general-purpose filtration medium made from natural cotton fibre. In liquid filtration, they retain solids mechanically, while the structural properties of natural cotton fibre also partially absorb non-emulsified free oil particles; this is an extra advantage in oil-containing process water. In dust filtration, they work on the dust cake filtration principle in shaker-type dust collectors; the dust cake building up on the bag surface gradually becomes the actual filtration medium.
The most notable features of cotton bag filters are their economical cost and easy availability. Their natural structure, free of silicone and contaminating additives, allows them to be used safely on food, beverage and sensitive process lines. However, synthetic fibre alternatives should be chosen for applications involving high humidity, chemical aggressiveness and high temperatures.
Product Identity and Technical Summary
Key Technical and Structural Features
- Fibre Type
- Natural Cotton
- Fabric Structure
- Needle-Punched Felt
- Micron Rating
- 1 µm · 5 µm · 10 µm
- 25 µm · 50 µm · 75 µm
- 100 µm · 150 µm · 200 µm
- Max. Operating Temperature
- 90 °C (liquid filtration) / 82 °C (dust filtration)
- Recommended Change-Out Pressure
- 2–2.5 bar
- Chemical Resistance
- Moderate resistance to common acids and alkalis; limited resistance to strong solvents.
- Moisture Resistance
- Low; dust filtration applications require a dry operating environment.
- Silicone Content
- Free of silicone and contaminating additives.
- Flammability
- Flammable; a flame-retardant (FR) surface treatment can be applied on request.
- Cleaning System Compatibility
- Liquid Filtration: Standard Bag Filter Housing
- Dust Filtration: Shaker Cleaning Systems
- Surface Treatment Options
- Plain
- Flame Retardant (FR)
- Usage Type
- Single use
Filtration Architecture and Working Principle
Cotton bag filters work in two different process environments depending on the application. In liquid filtration, mechanical retention comes first, while in dust filtration dust cake formation and the shaker cleaning cycle come into play.
In both applications, filtration takes place inside-out. Dirty liquid or dust-laden air enters the bag; particles are retained in the cotton fibre structure and the cleaned fluid passes out.
Mechanical Retention and Oil Absorption
Mechanical retention of solid particles, with additional removal of free oil in liquid applications.
Economical Dust Collection and Static Safety
Differential pressure is kept stable in dust filtration; in liquid filtration, timely replacement maintains filtration quality.
Advantages of the Cotton Bag Filter
With their economical cost and natural fibre properties, cotton bag filters offer a practical
solution for general-purpose liquid and dust filtration. Their silicone-free natural structure and the extra absorption that comes with the fibre give an added advantage in certain applications.
- Cost-Effective
- The lowest unit cost of all filtration media; a cost-effective choice for budget-constrained and general-purpose applications.
- Silicone-Free Natural Structure
- Natural cotton raw material free of silicone and contaminating additives; can be used safely on food, beverage and sensitive process lines.
- Dual Use
- Can be used both in standard liquid bag filter housings and in shaker-type dust collectors.
Cotton Bag Filter Surface Treatment Options
| Surface Finish | Property | Recommended Application |
|---|---|---|
| Plain | Its raw cotton structure is suitable for general-purpose standard filtration applications. | Woodworking, general dust collection and liquid filtration applications |
| Flame Retardant | Chemical impregnation slows the burning rate, but does not make it completely non-combustible. | Workshops with a risk of sparks and dust collection applications |
Engineer's Note
- Senior Process Engineer
- 15+ Years of Field Experience
- Field-Test Approved
The most common problem we see in the field with cotton bag filters is that on lines with high humidity or fluctuating moisture, the cellulose fibres absorb moisture, paving the way for bacteria/mould and eventually rotting. Also, with sudden temperature rises above 100 °C, cotton fibres lose their flexibility, become brittle and can no longer withstand the shaking pressure.
When should it be chosen?
Gives excellent results in grain mills, flour mills, woodworking, seed cleaning plants operating in dry conditions and general dust collection systems at ambient temperature (max. 82 °C). For organic dusts with a risk of sparks, FR-treated or antistatic bags should be used.
When should it not be chosen?
They must never be used on hot gas lines above 100 °C, in environments containing acidic or alkaline chemical vapours, or with moist/oily dust loads; in these processes, polyester or antistatic synthetic felt bags should be used.
Application and Selection Criteria
- Collar Type Compatibility
- Choose the collar type based on a photo or sample of your current filter; relying on catalogue dimensions alone is not enough.
- Temperature and Moisture Limits
- Gas temperature must not exceed 82 °C; high humidity and dew point transitions weaken the cotton fibre structure.
- Spark Risk
- For organic dusts with a risk of sparks, FR-treated or antistatic bags should be used.
Collar Types
A safe, leak-tight connection of the bag filter to the system starts with choosing the right collar. Six collar types, from PP rings to steel snap rings and from flanged designs to drawstrings, can be selected according to the design of your existing housing, the operating pressure and the requirements of the chemical environment. If you are not sure which collar type fits your filter housing, send us a sample or photo and we will make an exact replica.
PP Ring (Plastic Ring)
Polypropylene ring, stitched or welded. Used where full chemical resistance is required.
Snap Ring (Steel Ring)
Galvanised or stainless steel ring. The most widely used, economical standard collar.
Drawstring
Can be tied manually to any pipe outlet or special hanger with the drawstring.
Flange Top (Plastic Flange)
The plastic collar gives maximum sealing. Ideal for high-pressure systems.
Plain Top
Has no ring; suitable for machines with a special clamping device.
Snap Band
The flexible steel band clicks into its seat. Allows fast change-outs.
Performance Parameters
The liquid and dust retention efficiency, differential pressure stability and service life parameters of cotton bag filters under different process conditions are summarised below.
- Filtration Efficiency
- Provides high efficiency in the mechanical retention of solids in liquid filtration. In dust filtration, fine particle retention efficiency increases once a dust cake has formed; allow for a conditioning period with new bags.
- Service Life
- Adequate service life is expected in dry, chemical-free applications within temperature limits. Moisture, chemical contact or exceeding the temperature limit significantly shortens service life.
- Differential Pressure
- In liquid filtration, plan bag replacement when the differential pressure reaches 2–2.5 bar; complete the replacement before it exceeds 2.5 bar. In dust filtration, differential pressure largely returns to its initial value after shaker cleaning.
Industry Applications
Bag filters suited to different process needs are used across a wide range of industrial applications to protect product quality and production continuity.
01
Vegetable Oil
Clarity, purity and shelf life in vegetable oil and refining.
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02
Pipe and Profile
Cooling water filtration in pipe and profile extrusion.
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03
Paint Industry
Surface quality and pigment filtration in the paint industry.
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04
Glass Industry
Furnace and process filtration in the glass industry.
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05
Dialysis Centers
Water preparation and process filtration in dialysis centers.
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06
Foundry Industry
Equipment protection and dust filtration in foundries.
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07
Industrial Oil
Filtration in industrial oil production and recovery.
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08
Energy and Biogas
Maximum efficiency and turbine protection in energy and biogas.
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09
Recycling
Filtration for efficiency and environmental compliance in recycling.
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10
Food and Beverage
Hygienic filtration in food and beverage.
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11
Pharmaceuticals and Biotechnology
GMP-compliant sterile filtration in pharmaceuticals and biotechnology.
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12
Paper and Packaging
Process water filtration in paper and packaging.
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13
Chemical Industry
Corrosion-resistant, safe filtration in the chemical industry.
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14
Cosmetics
Microbiological safety and precision filtration in cosmetics.
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15
Machinery
Precision and technical filtration in the machinery industry.
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16
Printing and Ink
Flawless color and print quality in printing and ink.
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17
Metal and Surface Treatment
Flawless surfaces and bath stability in metal and surface treatment.
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18
Forest Products
Resin and glue filtration in forest products and furniture.
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19
Automotive
Precision process filtration for zero defects in automotive manufacturing.
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20
Oil and Petrochemicals
Equipment protection and process safety in oil and petrochemicals.
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21
Plastic Packaging
Precision process filtration and raw material purity in plastic packaging.
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22
Plastic Injection Molding
Cooling and hydraulic filtration in plastic injection molding.
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23
Water and Environment
Recovery filtration in water and environmental technologies.
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24
Shipyards and Marine
Operational safety and efficiency in shipyards and marine.
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Filter Selection Technical Checklist
- Operating Temperature
- Operate below 90 °C in liquid filtration and below 82 °C in dust filtration; at higher temperatures, synthetic fibre media should be chosen.
- Humidity / Water Vapour
- Dust filtration requires a dry environment; not suitable for processes with high humidity and a risk of condensation.
- Chemical Content
- Not suitable for chemically aggressive environments; should be considered for inert general dust and suitable liquid filtration applications.
- Oil Content
- In liquid applications, it can give an extra absorption advantage where non-emulsified free oil is present; confirm the emulsion state before application.
- Flammability
- For applications with a risk of sparks or flames, choose a bag filter with a flame-retardant (FR) treatment.
- Cleaning System
- In dust filtration it is compatible only with shaker systems; it is not suitable for pulse-jet and reverse-air cleaning systems.
- Food Compatibility
- The silicone-free natural cotton construction can be used in food and beverage applications under suitable conditions; suitability must be confirmed separately for each application.
- Cost Priority
- Offers an economic advantage in budget-driven, low-risk applications; for higher-risk processes, a suitable synthetic fibre medium should be chosen.
Points to Watch When Using Cotton Bag Filters
Key parameters to watch in operation and maintenance to maintain the process efficiency of cotton bag filters and prevent early wear and biological degradation:
- Operating Temperature Limit
- Operating temperature must not exceed 90 °C in liquid filtration and 82 °C in dust filtration; temperature monitoring is recommended.
- Oil Absorption Conditions
- If the aim in a liquid application is oil removal, confirm the emulsion state of the oil in the process liquid before commissioning.
- Timely Replacement
- If high humidity or chemical vapour is found in dust filtration, replace the cotton bag with a synthetic fibre medium.
- Flame & Fire Safety
- In applications with a risk of sparks or flames, use only FR-treated bags.
- Differential Pressure Monitoring
- In liquid filtration, plan replacement when the differential pressure reaches 2–2.5 bar; complete it before exceeding 2.5 bar.
- Initial Conditioning
- In dust filtration, allow new bags a conditioning period; do not over-shake before a dust cake has formed.
- Storage and Moisture Protection
- Store in a dry, ventilated place; damp storage increases the risk of biodegradation.
- Shaker & Hanger Mechanism
- When changing bags, check the shaker mechanism and hanger hardware in dust applications and the housing sealing surface in liquid applications.
Products that work with this product
Cotton Bag Filter
Your Questions Answered
Frequently Asked Questions
At Prosestim, we are committed to answering your questions and providing technical support for our filtration solutions.
What is a cotton bag filter?
Can it be used for liquid and dust filtration at the same time?
How does it retain oil?
What is the operating temperature limit?
It withstands up to 90 °C in liquid filtration and 82 °C in dust filtration.
Can it be used in humid environments?
Not in dust filtration; high humidity increases the risk of blinding and biodegradation. In liquid filtration, a liquid environment is normal.
What is the service life?
The service life of cotton bag filters varies with process temperature, humidity and dust load. In dry environments free of aggressive chemicals and below 82 °C they offer a stable service life, while high humidity and dew point transitions weaken the fibre structure and shorten the replacement interval. In liquid filtration, replace the bag when the differential pressure reaches 2–2.5 bar.
Can it be used in food applications?
The natural cotton construction, free of silicone and contaminating additives, can be used in food and beverage applications; confirmation for each application is recommended.
Is it flammable?
Yes, cotton is flammable. For applications with a risk of sparks, choose an FR-treated bag; however, FR treatment does not make it completely non-combustible.
Do you manufacture custom sizes?
Yes, custom production is available in non-standard sizes and configurations.
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