Can I get 1-micron filtration?
Yes, you can achieve filtration down to 1 micron with the correct fabric and surface treatment and the correct air to cloth ratio for your particular application. For wood dust we generally recommend polyester felt with a singed finish. However various applications require different weights of felt and surface treatments. Initially the polyester felt material filters the dust while building a “dust cake” on the singed surface of the felt. This dust cake then does the actual filtering of all subsequent dust that is blown into the bag. When the dust cake gets too thick, the material starts to “blind” or plug up, but the singed surface of the fabric helps to prevent a thick dust cake from adhering permanently. The dust cake will break away, leaving behind a thin layer to continue the process.
Why does my bag need to be oversized?
The purpose of an oversized bag is to achieve the proper air to cloth ratio. Most manufacturers of single stage units include the bottom bag into their calculation for air to cloth ratio. But once the bottom bag fills up that surface area is no longer capable of filtering.
What is the difference between the OEM’s standard material and polyester felt material?
Most of the OEM bags these days are made from a woven lightweight polyester sateen which has a rating of around 30 microns and a lower air flow rate than polyester felt. The felt that comes on most OEM collectors is better than the polyester sateen, but usually has no surface treatment. AFF’s singeing treatment helps promote a dust cake buildup and release which helps the bag “clean” itself as opposed to the plain felt of the OEM bags that causes dust and woodchips to adhere.