Filter bags are extensively employed as an economical filtration option in a variety of industries, they are well-suited for the clarification or separation of diverse liquids and gases.
When filter bag is placed in housing, it is good at capturing impurities in liquids, effectively increasing fluid use and reducing costs.
In this guide, you will understand the material of filter bag, their characteristics, and how to choose the right filter bag for your application.
1. Types of Filter Bag Material
When utilizing a filter bag for filtration of gases or liquids, the primary consideration revolves around material selection. Various materials possess distinct functions and characteristics.
Optimal material selection is pivotal in reflecting filter bag’s intended function and durability, thereby ensuring the attainment of the highest filtration efficiency.
When the removal of liquid deposits, adhesive particles, and impurities is required in industries like the water supply system and food & beverage, the top choice is polypropylene filter bag. Comprising 100% polypropylene, this filter bag conforms to FDA food-grade standards.
Furthermore, polypropylene filter bag exhibits outstanding corrosion resistance and is compatible with a wide range of corrosive solutions, including organic solvents, acids, bases, and oils. It also boasts high flow rate, with achievable speed ranging from 20m³/h to 40m³/h.
Pros of Polypropylene Filter Bag
- Chemical Stability:Polypropylene filter bag has excellent chemical compatibility, and it can keep its own properties unchanged in corrosive solutions such as acid or alkali.
- Hydrophobicity:Polypropylene, as a hydrophobic plastic, does not undergo expansion when exposed to water, making it can be used in environments where air humidity exceeds 10%.
- Purity:Crafted from 100% PP, polypropylene filter bag is entirely silicon-free, thereby promoting resource recycling and utilization while preventing environmental pollution.
- Consistency:Polypropylene filter employs a thermal welding design that ensures excellent sealing and consistently achieves a high filtration efficiency of over 99.9%.
- Non-toxicity:In accordance with FDA food grade standards, polypropylene filter bag is non-toxic and harmless, suitable for filtration in food, beverage and domestic water fields.
Cons of Polypropylene Filter Bag
- Limited Temperature Resistance: The maximum temperature limit for PP filter bag is 107℃, and is usually not suitable for high temperature applications.
- Chemical Resistance: PP filter bag is not suitable for highly corrosive chemicals.
- Low Wear Resistance:Polypropylene bag needs to be replaced more frequently when dealing with harder or sharp particles.
- Poor Treatment of Colored Substances:PP filter bag may not be able to effectively remove some colored materials, especially at high concentrations.
Polyester is created through the esterification of dicarboxylic acid and diol. It is then transformed into filter bag by subjecting it to multiple needle punctures and appropriate winding to create a structure where the fibers are not uniform but disorderly. This process includes repeated piercing with barbed needles to enhance fiber strength.
The polyester filter bag falls into the category of normal-temperature dust removal bags, designed for prolonged use in environments with temperatures below 150℃. It exhibits high dust removal efficiency and maintains a low emission concentration.
Pros of Polyester Filter Bag
- Smooth Surface:The surface of polyester filter bag undergoes process involving hot rolling, singeing, or coating finishing. This results in highly smooth texture, making it easy for dust to dislodge from surface.
- Long Service Life:Thanks to the structure of acupuncture non-woven fabric, polyester filter bag has strong structure to withstand wear and can be used for long periods without loss.
- Outstanding Air Permeability:Because of its large gap structure, the air permeability of polyester filter bag is more than 50% higher than that of ordinary calendering filter material.
- Good Wear Resistance: After multiple layers of winding and fiber reinforcement, polyester filter bag is very durable to prevent wear, even in high dust content environments.
- Low Emissions:Polyester filter bag contributes to emission reduction and the preservation of a cleaner, more healthful workspace.
Cons of Polyester Filter Bag
- Sensitivity to Moisture:The material of polyester decomposes when wet, so the polyester filter bag must be used in environment where the humidity is lower than 10%.
- Lower Thermal Stability:The polyester filter bag has limited heat resistance, and the maximum operating temperature does not exceed 150℃.
- Potential for Clogging:In applications containing sticky or viscous particles, polyester bag filter is easily blocked, thereby reducing filtration efficiency.
- Reduced Chemical Resistance: Polyester filter bag can filter general chemicals but is not suitable for handling highly corrosive products.
When it comes to the filtration of sizable particle impurities or applications requiring pre-filtering and coarse filtration, opting for a nylon filter bag is a sensible decision.
These bags are constructed from high-strength monofilament or compound silk nylon mesh, offering an economical solution that can be easily cleaned and reused.
Nylon filter bag is widely used in primary filtration of raw water, automobile oil removal, circulating water system, anticorrosive paint, reclaimed water treatment and other fields.
Pros of Nylon Filter Bag
- Consistent Aperture:Due to the uniform mesh structure, nylon filter bag has fixed pore size, which can maintain stable filtration accuracy and efficiency.
- Sealed Structure: After good welding process and strengthened outer edge seal, nylon filter bag is 100% sealed to avoid leakage during filtration.
- Good Tensile Strength: Good tensile strengthensures that nylon filter bag is not easy to deformation under the action of external force.
- High Filtration Efficiency: Nylon filter bag can meet the filtration requirements of 1-200μmin liquid filtration, dust removal and air filtration applications, and the filtration efficiency is up to 99.9%.
- Excellent Temperature Resistance:Nylon filter bag can be used in high temperature environment up to 170℃.
- Cleanable: The outstanding advantage of nylon filter bag is that it can be cleaned and reused for several times, effectively saving cost.
Cons of Nylon Filter Bag
- Limited Filtration Accuracy:Nylon filter bag is often used to capture big particle impurities in solution and is not suitable for fine filtration.
- Susceptibility to Moisture: Nylon filter bag can easily absorb water and undergo hydrolysis, resulting in shorter life span.
- Low Abrasion Resistance:As a textile wire mesh, nylon filter bag is less durable in applications with abrasive particles.
1.4 Stainless Steel
If you are looking for a filter bag that is more durable than plastic, stainless steel is your first choice. It has wire mesh structure made of premium stainless steel 304/316L.
Due to the particularity of metal material, stainless steel filter bag has excellent corrosion resistance and high mechanical strength. It can maintain high filtration efficiency at 480℃.
With rigid open hole structure, stainless steel filter bag can maintain stable high filtration efficiency of 99.9%, which is widely used in food&beverage, wastewater industry, chemical industry, oil refinery and other fields.
Pros of Stainless Steel Filter Bag
- Good High Temperature Resistance:Since the raw material is stainless steel 304/316L, stainless steel filter bag can withstand high temperature of 480℃.
- Extensive Chemical Compatibility:Stainless steel filter bag has good tolerance to all kinds of corrosive chemicals, like acid, alkali, etc., which is very suitable for use in chemical industry.
- High Replacement Pressure Difference:With high mechanical strength, stainless steel filter bag can withstand higher pressure, with replacement pressure difference of up to 0.2MPa.
- High Tensile Strength:Stainless steel filter bag can accept limited number of backwashes and is not prone to deformation.
- Washable and Reusable:Fabricated of stainless steel mesh screen, stainless steel filter bag is very easy to clean and support multiple reuse.
Cons of Stainless Steel Filter Bag
- Prime Cost:Compared with other materials of bag filters, stainless steel bag filter cost is higher, and the production process is complex.
- Limited Filtration Level:There may be limitations to stainless steel filter bags in extremely fine filtration.
- Space Requirement:The volume of stainless steel filter bag is large, which needs a large space for installation and use.
Crafted from 100% top-grade polytetrafluoroethylene (PTFE) fibers, PTFE filter bag is tailored for demanding industrial air filtration needs in harsh chemical environments, particularly at elevated temperatures.
PTFE filter bag demonstrates outstanding resilience against acids, alkalis, hydrolysis, and oxidation, consistently delivering high-performance results up to 260℃, withstanding occasional temperature spikes up to 285℃.
Thanks to its exceptional high-temperature resistance, PTFE filter bags find extensive application in a range of industries, including combustion boilers, waste incineration, titanium dioxide production processes, and post-combustion treatments, etc.
Pros of PTFE Filter Bag
- Strong Anti-Erosion Ability: As the top grade material for production of filter bags, PTFE filter bag can resist the erosion of acid, alkali, hydrolysis, oxidation, etc.
- Excellent High-Temperature Resistance:PTFE bag can operate at high temperature environment up to 260℃ and can withstand 285℃.
- High Purity Material:Made of 100% PTFE, PTFE filter bag is silicon-free and has self-lubricating capacity. Moreover, it is hydrophobic and not affected by wet environment.
- Huge Dirt Holding Capacity:PTFE filter bag can capture a large number of solid impurities or gel particles, with higher air permeability and long service life.
- Efficient Deep Filtration:With micron rating range from 1μm to 10μm, PTFE filter bag can remove tiny impurity particles.
Cons of PTFE Filter Bag
- General Wear Resistance:PTFE filter bag is easy to wear, so there are strict requirements on filter bag housing and use environment.
- High Cost: PTFE filter bag is usually more expensive than many other filter materials.
PPS, also known as polystyrene sulfide, is a new type of thermoplastic resin material, which can withstand 200℃ high temperature, and can meet the needs of flue gas purification in most fields, such as waste incinerators, coke ovens, kilns, chemical plants and so on.
PPS filter bag boasts a fibrous structure, outperforming other high-temperature, acid-resistant, and alkali-resistant filter bag products. It retains its exceptional performance even in the harshest of environments, ensuring an extended service life that meets or exceeds expectations.
Pros of PPS Filter Bag
- High Temperature Resistance:As a high-performance synthetic material, PPS is known for its excellent thermal stability, with being able to withstand temperatures up to 200℃.
- Compatible with Chemicals: PPS filter bag is inert to many chemicals, including strong acids and strong bases. It does not react with corrosive substances and is ideal in chemical corrosive environments.
- Good Wear Resistance:PPS is a high-strength synthetic material with strong molecular structure, so the PPS filter bag has extremely high durability and wear resistance.
- Excellent Filtration Performance:PPS filter bag is particularly effective in capturing fine particles, suitable for applications requiring removal of fine particulate matter from gases or liquids, with filtration efficiencies usually ranging from 99% to 99.9% or more.
- Retardant to Flame: With low flammability and self-extinguishing properties, PPS filter bag is not easy to ignite and burn continuously. It can maintain structural integrity and flame retardant even in high temperature environment, which meets fire safety standards.
Cons of PPS Filter Bag
- Easy Adhesion to Dust:In dusty environment, PPS filter bags can easily attach to dust and cause blockage, which may hinder filtration efficiency.
- Limited Tensile Strength: When the ambient oxygen concentration is higher than 12%, the tensile strength of PPS filter bag will be affected.
- Higher Cost: PPS filter material is usually more expensive than other filtration materials on the market, especially when large volume filtration is required.
- Moisture Sensitivity:PPS filter bag might experience hydrolysis if subjected to prolonged exposure to elevated humidity and water vapor.
1.7 Glass Fiber
These fibers are created by melting glass at temperatures ranging from 1300°C to 1600°C, drawing them from the molten state, and rapidly cooling them. This process results in filter bag’s remarkable resistance to high-temperature of 280℃.
Glass fiber filter bag boasts exceptional wear resistance, waterproofing, and oil repellency. It finds extensive application in industrial settings for tasks such as dust control, addressing air pollution, and recovering valuable dust, among other diverse fields.
Pros of Glass Fiber Filter Bag
- HighHeat Resistance: The biggest advantage of glass fiber filter bag is its high temperature resistance, which can maintain normal filtration in the environment of 280℃.
- OutstandingDust Removal Performance: With unique properties and design, glass fiber filter bag is very able to capture and remove particles and dust from industrial processes or air filtration systems with filtration efficiency of over 99.5%.
- Stable Structure:Due to the inherent strength and elasticity of glass fibers, glass fiber filter bag is designed to maintain its structural integrity under various conditions.
- Excellent Chemical Resistance:Excluding hydrofluoric acid and strong alkali, glass fiber filter bag is compatible with various corrosive chemicals.
- Good Moisture-Proof: Glass fiber filter bag does not absorb moisture, will not be affected by air humidity, and the performance is always stable.
Cons of Glass Fiber Filter Bag
- Brittleness:Glass fiber filter bag can be relatively brittle, which may result in the bag being more prone to breakage or damage when compared to some other filter materials.
- High Operation Resistance:Compared with general high temperature chemical fiber filter cloth, glass fiber filter bag has higher running resistance and the filtration speed is slightly slower.
- Low Tensile Strength:The wrinkle resistance of glass fiber filter bag is poor, and its service life will be affected under high strength tensile force.
Aramid, commonly recognized as Nomex, boasts exceptional heat resistance. The aramid filter bag is crafted from 100% high-strength aramid long fibers, following pretreatment and thermoshaping procedures.
In contrast to alternative heat-resistant materials, aramid filter bag offers a cost-effective solution with superior performance. This makes them the preferred choice in high-temperature industries such as power generation, coal boilers, incineration, chemical processing, mineral processing, asphalt mixing, steel production, and more.
Pros of Aramid Filter Bag
- High Temperature Resistance:Aramid is extremely melting resistant and can maintain high filtration performance even in 204℃ environment, so it is used in high temperature industries such as steel and asphalt plants.
- Durable Quality:Using 100% high strength aramid long fiber as raw material, aramid filter bag has strong structure and high mechanical strength.
- Excellent Wear Resistance:With good wear resistance and folding resistance, aramid filter bag is not easy to be broken.
- Flame Retardant：As a highly durable fire proof material, aramid filter bag is flame retardant to ensure the safety of high temperature filtration.
- Favorable Price:Compared with the filter bag of the same price, aramid filter bag has better performance and provides high cost performance.
Cons of Aramid Filter Bag
- Decomposability:Over time, the mineral oxides in aramid filter bag can result in degradation or partial decomposition.
- Cleaning Complexity:Cleaning and maintenance of aramid filter bags is more complex and time-consuming compared to other filter types.
Constructed entirely from 100% pure cotton, cotton filter bag is a reliable and high-grade solution for dust collection. It exhibits outstanding permeability and superior filtration efficiency, especially in dry environments.
Operational within temperature range of 82℃, cotton filter bag maintains a permeability rating of 20-25 CFM @ 0.5” gauge, effectively capturing over 90% of airborne impurities. This makes it an economical choice for filtration.
Furthermore, the cotton filter bag boasts a flame-retardant surface, rendering it suitable for a wide range of dust removal applications, including clean rooms, air purification, woodworking, and the cement industry, among others.
Pros of Cotton Filter Bag
- Bending Resistance:Cotton filter bag is soft, flexible and folded, and it is not easy to deform after extrusion or rubbing.
- Wear Resistance:Crafted from superior, robust cotton, cotton filter bag demonstrates remarkable resilience and extended operational lifespan. Its durability is such that even repeated use fails to compromise its filtration effectiveness.
- High Air Flow: Cotton filter bag is often used in vibrating dust collectors to capture and collect particulate impurities or dust in air, with air permeability up to 25 CFM.
- Easy to Clean: Cotton filter bag is very simple, can be directly cleaned, and reused after drying.
- Safe and Non-toxic:Having attained ISO9001 and FDA certifications, cotton filter bag meets the stringent standards for food-grade quality, ensuring it is suitable for direct contact with food products. This makes them a prevalent choice within food and beverage industry.
Cons of Cotton Filter Bag
- Chemical Resistance:Cotton filter bag is not suitable for filtering corrosive chemicals, it is good at capturing dust in air.
- Flamammability:Cotton is a very flammable material, but we have flame retardant treatment on the surface of filter bag, so it can filter normally even in 82℃ environment.
2. Select Filter Bag according to Applications
As a key decision of smooth production of factory, the choice of filter bag material is very important. We need to analyze according to the specific situation and demand of different industries to find the corresponding filter bag that can maintain normal production demand.
This section lists the several commonly used areas for filter bags and analyzes the factory environment and suitable filter bag materials one by one.
2.1 Metal Industry
In metal industry, filter bags are often used for dust collection, emission gas or product recovery. Due to the particularity of metal production, it generally needs to be carried out in high temperature environment, so the filter bags used in metal industry are high heat resistant.
When choosing filter bags for metal industry, temperature is the first factor to consider, followed by chemical exposure and legality, to determine the most suitable filter bags for specific applications in the metal industry.
The materials of filter bag suitable for metal industry are glass fiber PTFE, aramid, stainless steel, etc., which can efficiently capture impurities and dust in air in environment of 200℃ to 400℃, and the polyester filter bag can be used to collect normal temperature gas in steel mills.
2.2 Glass Industry
In the process of glass production, it is very important to emit particles and maintain clean working environment, which needs to be completed by the filter bags.
The selection of filter bag material also needs to consider many factors, such as glass production process temperature, operating environment and impurity type, etc.
Considering the environmental temperature, chemical composition of dust and other production requirements, we can choose the corresponding filter bags that can withstand high temperature and chemical corrosion to ensure the normal production.
PP and PTFE have excellent chemical resistance, and PTFE can be specially used to adsorb sticky or oil dust particles. For production conditions at high temperature from 200℃ to 480℃, then the filter bag made by aramid, stainless steel and glass fiber can meet the demand.
2.3 Cement Industry
Dust collection in cement industry is the most critical factor and needs to meet industry standards. When choosing filter bag in cement industry, the first thing to consider is the ability to absorb large amount of dust, followed by high temperature resistance and corrosion resistance.
Stainless steel filter bag demonstrates resilience against temperatures reaching 480℃ while also resisting corrosion. On the other hand, polyester filter bag boasts antistatic property, making it well-suited for the collection of dust in environments such as raw mills, clinker coolers, and other areas with medium temperatures and chemical exposure.
PTFE filter bag has excellent chemical resistance and is suitable for cement industry applications with sticky or abrasive dust. Aramid filter bag has excellent wear resistance and flame retardant, 204℃ high temperature resistance, is an effective low emission solution for cement industry.
2.4 Power Generating
As of 2022, over 60% of the globe’s electricity is produced by the combustion of fossil fuels, including natural gas, coal, and oil. The exhaust gas released from fuel combustion in boilers contains an array of pollutants, including but not limited to CO₂, SO₂, NO, PM, Hg, VOC, etc.
The release of gas emitted from power plants into the environment will cause high degree of environmental pollution. In order to control and reduce the pollutants in power plant emissions, it is very necessary to collect and filter the utilization treatment.
The choice of filter bag material is also very important. Considering the production environment of power plant and high particulate content of pollutants, we need filter bags with large air flow， abrasion performance, and excellent high temperature resistance. Polyester, PPS, PTFE, and glass fiber can meet these needs.
2.5 Chemical Industry
For filter bag used in chemical industry, the first thing to consider is chemical resistance. It needs to be able to withstand continuous exposure to strong acid&alkali, high temperature, humidity or other harsh environments.
In addition, fine chemical industry will emit gases with high dust content, which requires the use of having huge dirt holding capacity and easily cleaned filter bags to capture more impurities, reduces the replacement frequency and downtime, and extend the service life.
The filter bag materials suitable for use in chemical field including PTFE, aramid, polyester, polypropylene, etc., which can provide high filtration efficiency of more than 99% under challenging operating conditions, and are inert to various corrosive chemicals.
2.6 Asphalt Mixed Industry
The demanding conditions of asphalt mixing and production subject the filter bag to prolonged exposure in an environment characterized by corrosive dust and extreme temperatures.
Consequently, the filter bag must possess qualities such as high temperature resistance, wear resistance, flame retardancy, and efficient filtration capabilities to withstand these challenging operational conditions.
In asphalt mixing industry, materials including PTFE, glass fiber, polyester, PPS, with flame-retardant, high-temperature-resistant, and highly efficient dust removal materials are extensively employed.
Filter bag is commonly crafted with a blend of these materials or coated with additional substances to enhance and optimize their properties for the demanding conditions of asphalt production.
2.7 Food&Beverage Industry
Many products in food and beverage industry need to be filtered, such as milk, fruit juice, beer, cooking oil, syrup, etc. By using filter bags, the particles, gel and other impurities in liquid are captured and purified to effectively improve the cleanliness of food.
In order to avoid the impact of filter bag on product quality, we need to choose filter bag that meet the national food standards. At the same time, filter bag has to be subjected to various sterilization treatments in production room to meet the hygiene standards and sterility.
The filter bag materials that meet food safety standards are polypropylene (PP), PE and nylon, which are non-toxic and produced in dust-free workshop and through ultraviolet sterilization, γ-ray sterilization and other sterilization methods, to ensure the safety of food.
2.8 Pharmaceuticals Industry
Given its commitment to stringent standards, pharmaceutical industry places paramount importance on safety and efficacy. In pursuit of maintaining drug purity and preventing contamination, the utilization of filter bag becomes imperative for the filtration and separation processes integral to drug production.
In pharmaceutical industry, product cleanliness, safety, and purity are crucial, and the selection of filter bags needs to meet these stringent requirements.
In addition, the selected materials must meet regulatory standards, including those established by organizations such as the FDA and EMA. The filter bag materials that meet these criteria include PP, PTFE, nylon, polyester, glass fiber, cotton, etc.
3. Other Factors to Consider When Selecting Filter Bag Material
The difference between various materials of filter bag mainly lies in temperature resistance, chemical resistance and moisture resistance. This part mainly uses these three aspects to analyze which filter bags can be used in different environmental conditions.
In addition, the purchase budget is also a factor to consider when choosing filter bag. Because some filter bags are affordable and some are expensive, so we need to consider comprehensively according to their own needs, and finally choose the most appropriate filter bag.
The temperature of dust-containing gas that needs to be filtered is the primary consideration for screening filter bag material. Dust-containing gases below 130℃ belong to normal temperature gases, while dust-containing gases above 130℃ are high temperature gases.
When at room temperature, you can use conventional filter bag materials, such as polyester fiber, polypropylene, cotton, etc. The filter bags of these materials are not suitable for use in high temperature environment, otherwise it will affect the filtration efficiency.
If the temperature is higher than 130℃, it is necessary to choose high temperature resistant filter bag materials, such as nylon, stainless steel, PTFE, PPS, glass fiber, aramid, etc., to efficiently filter the dust gas in high temperature environment, avoid the emission of pollution gas, and maintain continuous industrial production.
Dust-containing gases can be divided into three categories according to the relative humidity: dry gas (humidity <30%), normal gas (humidity 30%~80%) and high humidity gas (humidity> 80%). Materials of filter bag have different moisture resistance, so they can be used in different fields.
Polyester exhibits effective resistance to moisture, making it suitable for environments with low to moderate humidity levels. Polypropylene and PTFE not only possess resistance to moisture but also demonstrate resilience against various chemicals, making it well-suited for industrial settings characterized by high humidity.
If it is high temperature and high humidity environment, then to avoid the use of high temperature resistant filter materials. Aramid and glass fiber are suitable for high temperature and humidity applications, such as cement, asphalt, metal smelting and other industries.
3.3 Chemical Property
Selection of suitable filter bag materials based on chemical resistance is essential to ensure the service life and effectiveness of filtration systems in industrial applications.
The compatibility of filter bag material with various chemical components such as acids, alkali, oxidants and organic solvents should be considered.
Cotton filter bag should avoid contact with corrosive chemicals, PP and polyester filter bags can filter general chemicals, but not for highly corrosive chemicals.
PTFE and aramid have excellent corrosion resistance, but also high temperature resistance, and are often used in demanding extreme environments. They are not affected by temperature and acid-base corrosion, and can always maintain high filtration efficiency greater than 99%.
3.4 Purchase Budget
The cost of filter bag is also a factor to consider when choosing material. PTFE and aramid are high-cost materials, they all have excellent chemical resistance and high temperature resistance, often used in harsh environments and have long service life.
If you want to buy more cost effective filter bags, then stainless steel, polypropylene and polyester are excellent choices. They are relatively common and cost-effective materials, with good corrosion resistance and moisture-proof performance, suitable for applications with moderate chemical resistance requirements.
Glass fiber and nylon are the most economical and efficient filter bag materials, they have smooth surface and fibrous structure, with outstanding moisture resistance, in a humid environment to avoid dust blockage, adhesion, provide excellent filtration performance.
This article provides detailed exploration of how to choose the material for filter bags from several aspects, including advantages and disadvantages of different materials, common applications, temperature resistance, chemical resistance, moisture resistance, and product budget considerations.
Whether it is the adaptability of polyester and polypropylene, the elasticity of aramid and PTFE, or the cost-effectiveness of materials like glass fiber, nylon, the choice ultimately depends on unique needs of your application.
In summary, according to this guide, you can address the complexity of filter bag material selection. Your choice will be important in efficiency, life, and cost effectiveness of filtering system, ultimately contributing to the success of your specific industrial or environmental applications.
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