Monofilament Polyester Bag Filter
Precise Woven Pores, High Flow and Washable Reuse: 20–1000 µm
A monofilament polyester bag filter is a woven surface filter offering a precise woven pore structure, high flow and the ability to be cleaned and reused.
100–180 mm
230–810 mm
20–1,000 µm
135 °C (275 °F)
What Is a Monofilament Polyester Bag Filter?
Monofilament polyester filter fabric is a woven fabric produced by processing yarn, extruded as a single strand from heated polyester, on precision looms. Unlike felt bag filters, it performs surface filtration rather than depth filtration: particles are retained on the inner surface of the fabric and do not penetrate the fibre. This structure allows the filter to be washed and reused.
The most notable advantages of the monofilament structure are that it can be washed and reused and that it does not shed fibres. It is the preferred choice especially in processes that must retain rigid, solid particles of 20 µm and above, run at high flow rates and where the economics of reuse matter. Paint lines, CNC coolant, automotive washing processes, resin and ink filtration and chemical process lines are the most common applications.
Product Identity and Technical Summary
Key Technical and Structural Features
- Material
- 100% monofilament polyester filter fabric
- Micron Rating
- 20 · 25 · 30 · 50 · 75 · 100 · 150 · 200 · 300 · 500 · 750 · 1,000 µm
- Max. Operating Temperature
- 135 °C (275 °F)
- Recommended Change-Out Pressure
- 2–2.5 bar
- Surface Finish
- Woven; no surface treatment applied
- Seam Construction
- 5-Thread Industrial Stitching
- pH Range
- 4–9
- Food Compatibility
- Raw material suitable for food contact
- Specific Gravity
- 1.38 g/cm³
- Yarn Structure
- Single-yarn (monofilament) weave; fixed pore size
- Reuse
- Washable and reusable
Filtration Architecture and Working Principle
Monofilament polyester bag filters pass dirty liquid from the inside of the bag to the outside in a two-stage treatment process. Surface filtration and differential
pressure monitoring allow the system to work correctly and to be serviced on time.
Filtration takes place inside-out: dirty process liquid enters the bag and all particles are retained on the inner surface of the bag. The filtered clean liquid collects in the space between the bag and the body and leaves through the outlet. The stainless support basket on the outside keeps the bag in shape at high differential pressures.
Precision Surface Filtration
The single-filament monofilament weave gives exact, precise control of the micron cut-off on the line. Because particles are held at the surface rather than escaping into the depth of the filter, the filter cake is easily scraped off and washed; differential pressure is kept under control and flow stays balanced.
Washability and Reuse
Unlike felt bags, the pore structure is largely recovered by washing, which is a clear advantage in terms of unit cost and waste. However, washing efficiency varies with particle type and size; in critical processes, performance after washing should be verified.
Advantages of the Monofilament Polyester Bag Filter
The monofilament polyester woven surface offers a consistent pore structure and the economics of reuse thanks to its precise weave geometry. High flow capacity, low pressure drop and a very low risk of fibre migration make MF PE bag filters the preferred choice in processes where clean product quality is critical.
- Precise Pore Structure
- Precision weaving gives a consistent pore structure engineered for filtration; there is no fibre swelling as with felt.
- Surface Filtration
- Particles are retained only at the woven surface; the surface can be cleaned and the bag reused.
- Reusable
- A pore structure that is largely recoverable by washing significantly reduces unit cost and waste.
- Low Pressure Drop
- The open weave geometry keeps flow resistance low even at high flow rates, reducing energy consumption and pump load.
- No Fibre Migration
- The monofilament structure has a very low risk of fibre breakage, reducing the risk of fibres getting into the clean product.
- High Temperature Resistance
- Stable operation up to 135 °C; used safely in hot processes where PP and nylon fall short.
- Chemical Resistance
- Reliable chemical resistance in the pH 4–9 range; a wide range of industrial applications.
- Food Compatibility
- Raw material suitable for food contact; can be used safely on food and beverage lines.
- Mechanical Strength and Dimensional Stability
- High-tensile polyester fibres keep their form under flow fluctuations and maintain the bag's geometry.
Bag Diameter and Length Options
100 mm Diameter
Suitable for small-scale systems and laboratory-type filter housings.
180 mm Diameter
The industry-standard size and the most widely used size for high-flow systems.
Custom Manufacturing
Bags can be made to sample for older or imported special equipment.
- 180 × 430 mm
- Standard Large Diameter • Short Length (~0.25 m² Filter Area)
- 180 × 810 mm
- Standard Large Diameter • Long Length (~0.50 m² Filter Area • Most Common)
- 100 × 230 mm
- Compact Small Diameter • Short Length (~0.08 m² Filter Area)
- 100 × 380 mm
- Compact Small Diameter • Long Length (~0.14 m² Filter Area)
Micron Options and Precision
| Micron | Application |
|---|---|
| 20 µm | Fine coarse filtration; final stage for paint |
| 25 µm | Fine coarse; pre-stage for resin and ink |
| 30 µm | General coarse filtration; cooling water, CNC fluid |
| 50 µm | Medium coarse; chemical process lines |
| 75 µm | Medium coarse; paint and coating lines |
| 100 µm | Standard coarse; pre-stage for water treatment |
| 150 µm | Low pressure, high flow; hydraulic pre-stage |
| 200 µm | Coarse pre-filtration; wide particle retention |
| 300–500 µm | Very coarse; plastic granules, aggregate separation |
| 750–1,000 µm | Special coarse separation; industrial wash water |
Collar Types and Adapters
PP Ring (Plastic Ring)
Polypropylene ring, stitched. 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.
Engineer's Note
- Senior Process Engineer
- 15+ Years of Field Experience
- Field-Test Approved
The most common problem we see in the field with polyester monofilament (single-yarn, open-mesh woven) bag filters is their use instead of felt bags on lines with gel-like, deformable or high-TSS solids that need depth filtration, causing the filter to blind quickly at the surface. Also, although monofilament bags can be washed and reused, uncontrolled washing with pressurised water can distort the woven pore geometry and cost the bag its micron precision.
When should it be chosen?
Suitable for surface screening filtration where an exact particle cut-off is required: automotive electrocoat circuits, paint, resin, adhesive, varnish and high-viscosity coating lines. A safe choice for process stages where fibre migration is not acceptable.
When should it not be chosen?
For coarse, sludgy water with a wide particle size distribution, gel-like organic contaminants and lines where in-depth dirt holding is expected, needle-punched polyester felt or polypropylene felt bags should be considered instead of monofilament.
Application and Selection Criteria
- Collar Type and Filter Housing Fit
- Choose the collar type based on a photo or sample of your current filter; relying on catalogue dimensions alone is not enough.
- Controlled Washing
- Wash with low-pressure water from the outside of the bag towards the inside; a high-pressure jet can distort the woven pore geometry and reduce micron precision.
- Chemical and Thermal Resistance
- Do not put into service without confirming operating temperature and chemical compatibility.
- Bag Length and Basket Fit
- Choose a bag about 10 cm longer than the restraining basket. A bag the same length as the basket is stretched and tears under pressure; this is the most common cause of "burst bag" complaints in the field.
Industry Applications
Bag filters suited to different process needs are used across a wide range of industrial applications to protect product quality, protect equipment and support 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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Performance Parameters
The process performance of polyester monofilament bag filters is assessed on the high flow permeability provided by the precise woven pore structure, exact particle cut-off precision and keeping the risk of leakage at the collar under control.
- High Flow
- High liquid throughput at low differential pressure thanks to the open weave and large surface area.
- Micron / Service Life Balance
- The right micron rating delivers the required clarity and extends the time before the filter clogs.
- Sealing
- Industrial stitching and the right collar choice minimise the risk of bypass (leakage).
Filter Selection Technical Checklist
- Chemical Nature of the Fluid
- Polyester filter fabric is suitable in the pH 4–9 range; for acidic or alkaline fluids outside this range, PP or PTFE should be considered.
- Operating Temperature
- Stable operation up to 135 °C; above that, PTFE or metal mesh filters should be chosen.
- Required Cleanliness Level
- For requirements below 20 µm, a felt bag or a cartridge filter should be chosen.
- Flow Rate
- Suitable for high-flow systems thanks to its low pressure drop.
- Viscosity
- With high-viscosity liquids such as resins and heavy oils, pore clogging accelerates. Choose the micron rating accordingly.
- Collar (Ring) Type
- When reusing, check the sealing surface at every installation.
- Solids Load
- With a very high solids load, a felt bag has the advantage; the woven surface can clog quickly.
- Food Approvals
- If there is food contact, choose food-contact-compliant MF PE.
- Maximum Pressure
- Always check the pressure difference that the filter body and bag can withstand.
- Reuse
- Establish a washing protocol and verify filtration performance after washing.
- Bag Length
- Choose the bag length according to the filter housing model and flow requirement.
Points to Watch During Use
Getting maximum efficiency and life from a monofilament polyester bag filter depends on correct installation, regular washing and reuse protocols.
Sudden pressure fluctuations, incorrect installation, early clogging or inadequate washing can permanently damage the pore structure and reduce
filtration efficiency.
- Initial Start-Up
- Sudden pressure surges should be avoided when the filter is first put into service.
- Timely Replacement
- Wash or replace the bag when the differential pressure (ΔP) reaches 2–2.5 bar.
- Post-Damage Check
- If the old bag is deformed, torn or bypassing at the edge, check not only the bag but also the filter basket and the sealing surface.
- Pore Integrity Check
- Before reusing a washed bag, check the pore integrity with light or visually; if micro-tears or deformation are found, take the bag out of service.
- Correct Placement & Installation
- The bag must be placed correctly in the filter basket and inside the housing.
- Basket and Seat Check
- At every change, check that the support basket is not deformed and that the bag is fully seated.
- Collar (Ring) Protection
- The bag collar (ring) must not be damaged during installation and removal.
- Even Lid Tightening
- The housing lid should not be overtightened; deformation of the collar creates bypass.
Products that work with this product
Monofilament Polyester 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.
When should I replace the bag filter?
When the differential pressure exceeds the recommended threshold (2–2.5 bar), washing should be tried first. If the pressure does not fall after washing, or if visible damage is found, the bag should be replaced.
Can monofilament bags be washed and reused?
Yes, this is one of the most important advantages of monofilament polyester woven bags. Washing can be done with water or a suitable solvent. However, washing efficiency may be lower with sticky particles; a visual pore check after washing is recommended.
Why does bag length matter?
It directly determines the filtration surface area; a short bag means lower flow capacity. The length must match the filter housing model.
Do you have food-contact-compliant monofilament filters?
Yes, for the food and beverage industry we manufacture with raw material specifically suitable for food contact.
What is the maximum temperature it can withstand?
Monofilament polyester bags withstand up to 135 °C. For higher temperatures, PTFE or metal mesh filters should be chosen.
Can it be used with gelatinous or semi-solid particles?
It can be used on lines where rigid particles are retained; however, with gel-like or deformable contaminants the woven surface can clog quickly. For such processes, felt bags that provide depth filtration should be chosen.
What is the main difference between a felt bag and a monofilament woven bag?
A felt bag provides depth filtration, works in the 1–200 µm range and is single-use. A monofilament woven bag provides surface filtration, works in the 20–1,000 µm range and can be washed and reused. They are complementary products, not competitors.
How do I know which micron rating to choose?
It is chosen according to the smallest particle size to be retained. If unsure, it is recommended to start with 100–150 µm and monitor the differential pressure.
Do you manufacture custom sizes?
Yes, custom production is available in non-standard lengths, diameters and micron ratings.
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