Three Types of Filter Media
Felt is a single layer of polypropylene, polyester, nylon, nomex® or Teflon® perforated with special barbed needles from both surfaces. The resulting pore structure is comprised of long entangled fibers and the non-needled portion consists of a higher density layer of compressed fiber, providing depth filtration. This is the most common filter bag media and typically for nominal retentions within 1 to 200 microns.
Meltblown filter bags are made from melted polypropylene pellets which are extruded into small diameter fibers used for forming specific density and thickness filter bag material. This type of filter bag provides depth filtration and therefore has higher particle loading capability. Due to the precise manufacturing process the retention can be 99% efficient for particle sizes as small as 1 micron. Some filter bags are designed with several layers of varying density reserving the higher density material for only the smaller particles, increasing the overall filtration area and maximizing retention.
Polypropylene Felt and Mesh is the most common filter media material because of its' strength and general resistance to most industrial fluids including acids (mineral and organic) and alkalis (except NaOH and KOH). Polypropylene also has fair resistance to most organic solvents and can be used for continual operating temperatures up to 194°F.
Polyester Felt and Mesh is generally used for nominal retention applications where polypropylene is not compatible either because of chemical incompatibility or higher temperatures. Polyester also has fair resistance to most organic solvents and can be used for continual operating temperatures up to 275°F.
Nylon Felt and Mesh are selected when either material compatibility or operating temperatures preclude using polypropylene or polyester materials. It has good resistance to alkalis and organic solvents and can be used for continual operating temperatures up to 250°F.
Nomex® Felt is for nominal filtration applications for higher temperatures, up to 375°F. Nomex® resists common alkalis and organic solvents. Our selection of Nomex® Felt is limited to only 5, 25 and 100 micron nominal retentions.
Teflon® Felt and Mesh is the most costly filter bag material we offer and considered the "material of last resort". It's the only material we offer for continuous operating temperatures up to 500°F and has excellent chemical resistance.