Selecting the right filter media for dust extraction
Filter bags are one of the most important components of your dust collection unit. They are also often the most underrated by our customers. Choosing the correct filter media for your dust extraction bags is critical as it impacts on process and down time. DRM’s team can guide you through the selection process that can be split into 3 steps:
Step 1: Process environment
Choosing the right polymer for the dust extraction bags is the first step. The polymer has to be able to withstand your process environment before you can think about dust extraction. DRM offer felt in a wide range of polymers, from standard polyester to PTFE, Meta Aramid or PPS. Our team are able to advise on the polymer suitable for your dust extraction unit.
Step 2: Dust cake formation
The needle felt doesn’t filter on its own. The whole process of dust extraction relies on the formation of a dust cake. The needle felt provides a surface that allows for dust particles to accumulate and supports the dust cake. The cake acts as a filter to provide a high filtering efficiency during the unit’s operation. Having chosen the polymer for your dust extraction bags in Step 1, the technical team at DRM will next advise you on different available weights, micron ratings and finishes based on your dust to ensure good cake formation.
Step 3: Dust cake release
Once the filter efficiency/pressure drop is no longer in the right balance, the dust cake needs to be removed. The unit shakes or blows the dust off the dust extraction bags and the more efficiently this is done, the longer the dust extraction bags will last. Excessive dust build up can be caused by problems with the cleaning system or moisture in the dust collector. If your dust hardens on the bags and is not easily dislodged when the bag is shaken, moisture may be a problem in your unit. Moisture can form on the dust extraction bags from crossing of the dew point, high moisture content in the inlet stream, use of compressed air or leaks in the process equipment.
In this third step, DRM will optimise the media selection to work in your specific environment for maximum dust extraction bag life and process performance. Filter media come with a variety of finishes and treatments to aid cake release and to protect the dust extraction bags from blinding through excessive dust cake build up. Our full selection of finishes is detailed in the table below:
|Fibres are melted to give a smoother finish and improved cake release with free flowing dusts
|Improves dust cake release for sticky dusts that are prone to agglomeration
|Hydrophobic & Oleophobic
|Liquid and/or oil repellent finish that aids cake release with dusts that become sticky or greasy with moisture
|Liquid repellent finish that protect the media from acidic environments
|Conductive stainless steel or carbon fibres are added to the fabric to eliminate sparking from electrostatic discharge
|Foamed or cellular surface layer for fine and abrasive dusts
|Thin layer of PTFE to retain fine particles, down to 1µm
|Reduces the risk of fire spreading in flammable environment