Choosing the right cartridge air filters makes a big difference in the overall efficiency and cost-effectiveness of your dust collection system. Filter selection is about more than just filtration efficiency—you also have to consider the base filter media, coatings and other options. The right choice depends on the characteristics of your dust. 

Understanding Cartridge Air Filter Options

Cartridge air filters consist of a cylindrical or conical filter element made from pleated filter media. This pleated design increases the surface area for filtration, allowing for efficient particle capture. The cartridge is housed in a metal or plastic frame that directs the airflow through the filter media, trapping dust and particles while allowing clean air to pass through. Cartridge filters are differentiated based on the composition of the filter media (the substrate) and the presence of special coatings, chemical treatments or other materials embedded with the substrate.

Cartridge air filters utilize various substrates to cater to different dust collection needs. The primary substrates include cellulose, polyester, and a blend of the two.

• Cellulose filters are economical and effective for capturing larger dry particulate. These filters typically come in MERV ratings of 10-12 and are good general-purpose dust collector filters. (Note that all cartridge filters will approach a MERV 16 rating as they build up a dust cake.)
• Spunbond polyester filters are made from a nonwoven fabric media composed of polyester fibers bonded together using a chemical or thermal process. These filters are highly durable and resistant to chemicals, humidity and high temperatures. This makes them suitable for challenging environments and applications involving sticky or hygroscopic (moisture-absorbing) dust. Spunbond polyester filters may come in MERV ratings up to 15 for enhanced capture of smaller particulate. Some polyester filters are even washable (for a limited number of times), which can be a benefit when dealing with sticky dust. 
• Blended filters combine the strengths of both materials, providing a balance of cost efficiency and longevity. Compared to plain cellulose filters, they offer enhanced durability and moisture resistance. These filters are a good choice for environments with moderate humidity and for applications with heavier dust loads, highly abrasive dust or moist dust. Blended filter media may have MERV ratings between 10-13. 

Coating options enhance filter performance by addressing specific operational challenges.

• PTFE (Polytetrafluoroethylene) coatings make filters more resistant to sticky particles and moisture, reducing clogging and extending the filter’s lifespan. PTFE forms a thin membrane with tiny pores over the substrate, which may be cellulose, polyester or a blend. In addition to increasing chemical, moisture and abrasion resistance, the PTFE coating also provides higher filtration efficiency, up to MERV 14-16. These filters are ideal for moist, oily, sticky or abrasive particulate. 
• Nanofiber coatings improve the filter’s ability to capture fine particles, significantly enhancing filtration efficiency. Nanofiber filters have nano-scale fibers layered on top of the substrate, usually a polyester or polyester/cellulose blend. With efficiency ratings up to MERV 16, nanofibers can capture fine particulate down to the submicron scale, such as fine food dust created by milling, grinding or spray drying. 

Additional treatments are available to meet specialized needs in challenging environments and enhance safety and efficiency. Rather than a surface coating, these filters use chemical treatments or materials infused into the filter media.

• Fire-retardant treatments reduce the risk of combustion, making them essential for high-heat environments. This is usually a cellulose or blended filter media impregnated with chemicals that inhibit combustion. They may be recommended when working with flammable or combustible food dust. The flame-retardant treatment may be an option that can be added to standard filters. 
• Oleophobic filter media repels oil and grease, preventing clogging and maintaining filter efficiency in environments where oily aerosols or greasy dust are present. While a PTFE coating is one way to make filters oil-resistant, other types of oleophobic media use fluorinated polymers blended directly with the base material. These filters can have many benefits for food applications where oily or greasy particles are present (such as nut processing, spray drying and snack food production) or environments with higher moisture content in the airstream. 
• Static-resistant filters minimize the buildup of static electricity. Anti-static filters have special coatings or conductive fibers woven with the filter media to inhibit static buildup. This may be recommended when dealing with fine, combustible dust that can build up a static charge, such as flour or cornstarch.

Image courtesy of Robovent

Considerations in Cartridge Filter Selection for the Food Industry

Selecting the right filters for dust collection in the food industry is crucial to maintaining a clean, safe and efficient processing environment. Various factors, such as the nature of the dust, the processing conditions and regulatory requirements, must be considered to ensure optimal filter performance and longevity. Here are a few questions to ask:

Consider using oleophobic filters or PTFE-coated filters to repel oils and maintain efficient filtration in environments where oils or grease are present.

Almost all food dusts (such as flour, sugar, starches, cocoa powder, powdered dairy, etc.) are combustible under the right conditions—some highly so. When dealing with flammable or combustible dusts, it may be advisable to consider anti-static and/or fire-retardant filters to reduce the risk of ignition and ensure safety.

Dust in food processing ranges from heavy, coarse dust to ultrafine dusts and powders. For fine dust, consider filters with nanofiber coatings or higher MERV ratings to capture smaller particles effectively.

Bakeries, confectioneries and other food manufacturers often deal with steam and moisture from cooking processes. Polyester or blended filters with moisture-resistant coatings are ideal for maintaining performance in humid conditions.

Sugar dust, in particular, can often cake on dust collector filters. PTFE-coated filters are effective at resisting sticky particles and maintaining airflow. Another option for sticky sugar dust would be washable polyester filters (usually washable for a limited number of times).

Spunbond polyester is a better choice for high-temperature applications in food processing facilities. These filters do a better job of standing up to the heat.

Food applications like nut or seed processing and cereal production can produce large volumes of coarse, abrasive dust. Spunbond polyester filters offer enhanced durability against abrasive particles. PTFE coatings also increase durability. Finally, consider protecting the cartridge filters with pre-filtration or a dropout box to allow the heaviest particles to fall out of the airflow.

By asking the right questions and understanding the specific needs of your food processing application, you can choose filters that enhance safety, efficiency, and compliance. Whether dealing with oily, combustible or ultrafine dust particles, tailored filter solutions will help maintain a high standard of air quality while increasing filter life and reducing maintenance time and costs.

Check out the rest of our air filtration series: 

• Choosing the Right Dust Collector
• Understanding Filtration Efficiency 
• Care and Maintenance of Cartridge Filters (coming soon!)

 For more information, download the Cartridge Filters Buyers’ Guide