How to choose a bag filter
Author:huahang Time:2016-03-02 16:37:51
How to choose a bag filter
1 Media Selection
You should choose the media from which your filter bags will be constructed based on the type of application they will be used for. Take the
following things into consideration prior to selecting your media:
1.1 Temperature - do your bags need to withstand extreme temperatures
1.2 Product - what are you filtering
1.3 Chemistry - can your bags withstand the chemical make up of the dust particles
1.4 Resistance- is the filter media able to resist the wear and tear of the dust particles
2 Size
Accurate measurements lead to the best fit. Most dust collectors have been upgraded over the years due to the need for new permits which called for
reconfiguration of the bag house in which case OEM configurations will not fit. Because of this you will need to obtain accurate measurements for your
filters before ordering replacement filter bags. If you currently have filter bags installed that are functioning properly, you can pull out one of those bags
to get the proper measurements for your replacement order
3 Construction
Some people prefer a sewn bag seam for the perceived assurance of the strength of a mechanically secure, sewn seam. Obviously if the seam
fails and the bag breaks, dirt will enter the downstream flow. One area of concern with a sewn seam is the small holes made by the needle that
sews the bag. These holes, if larger than the micron rating of the bag, can allow unwanted material to by-pass the filter bag. This can be a greater
problem if the bag is not properly sewn. A good quality bag will be made from media that is silicone free and will be sewn with silicone free thread
so that the filtrate is not contaminated.
4 Micron Ratings
Filter bags are generally available in micron ratings from 1/2 to 1200. It's important to know that almost all bags have what's called a "nominal" rating.
This means that the bag will allow some percentage of particles larger than its micron rating to by-pass the bag. In other words, a nominally rated 25
micron bag will allow some larger than 25 micron particles to enter the downstream flow. This usually is not a problem since, in many applications,
the proper size bag is determined through testing different micron ratings to determine the one that will retain the required size particles. Absolute rated
bags are available that will stop 99.9% of the rated size particles but they can cost up to 30 times what a nominal rated bag does.
