Filter Bag Micron Ratings Explained

One micron is a unit of length equal to one millionth of a meter, using the symbol: μm.

Filter micron levels specify the average size opening in the filter media. If a polyester fiber filter bag is rated for 20-micron filtration, the average size opening between fibers is 20 micron.

Typically, filter media is given a micron rating based on an 80% efficiency, meaning that the filter will remove 80% of contaminants greater than 20-micron if you are using a filter bag rated for 20 micron.

 

Nominal vs Absolute Micron Ratings

Most filter bags are rated with what’s called a “nominal” micron rating, meaning that a percentage of particles larger than the specified micron rating will pass through the bag. An “absolute” micron rating will filter 99.9% of particles at the specified micron rating.

Absolute-rated bag filters are significantly more expensive when compared to a nominal-rated bag filter. For most applications, using a nominal-rated filter bag allows for users to achieve the desired end result or product at a much more affordable cost.

Approximate Micron of Common Materials

 

 

** H20 Warehouse.com: https://www.h2owarehouse.com/info-micron.htm

*** INDUSTRIAL SPECIALTIES MFG. & IS MED SPECIALTIES (ISM): https://www.industrialspec.com/resources/mesh-and-micron-sizes/

**** Commercial Filtration Supply: https://www.commercialfiltrationsupply.com/education/a-better-understanding-of-micron-ratings.html

For more information on bag filters, read our Bag Filter FAQs or speak with a PRM Filtration expert today.