Chemical Attack- If your fabric filter bags have deteriorated down the entire length of the bag, then the failure is likely due to an exposure of acid or alkaline outside of what your filter media can withstand. Your gas/ dust pH is among the variables considered to determine the best filter media and fabric construction for your application. There may be blotches, water stains, and discoloration visible on the failed bag.
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If your bags are charred or melted when they have worked fine before, it’s likely that build up in the hopper trapped heat and caused operating temperatures to surge. The filter bag in the picture was burned as the tube sheet overheated.
In pulse bags a broken cage wire can quickly tear a hole in a filter bag.
If the bottom six inches of the bag are the only point of abrasive failure, it’s likely that other cages are rubbing against it. A filter bag with a wear strip or bump cuff will prolong bag life by doubling the amount of fabric where the abrasion occurs.
If dust contains crystalline particles, it is important to avoid over cleaning. Each time the filter starts up on clean bags, the smallest abrasive particles blast right through the fabric, tearing little holes as they go. Leaving a decent filter cake on after pulsing allows those tiny sharp particles to embed into the filter cake, preventing premature bag failure.
Burst bags- Fabric that has burst just under the cuff or at the disc bottom indicates aggressive bag cleaning. Reduce psi while staying within acceptable pressure.
Partial Change-out, new bags blinded quickly- Many facilities will change only part of their baghouse filters at one time, in an effort to save on maintenance costs. I do recommend changing a few bags that have prematurely failed, but changing half the collector simply puts the clean bags on double duty until they are as blinded as the old half. When pulling vacuum, air/ gas will follow the path of least resistance into the new, clean filter bag. It will continue passing by the older filter bags in favor of the newer more permeable bags until the overload balanced out the amount of particles embedded within the filter media of each bag, new or old, and equal airflow is reestablished. If it is a money timing issue, consider putting on a blanket order with NFM and releasing/ paying for only part of a set monthly or quarterly leading up to a full change-out.
Snap band issues- Check out NFM’s exclusive SNAPPER CUFF. This one piece snab band has no seam and prevents seal issues.
Dusting- Find leaks with glow powder and NFM’s black light. No sense in changing a whole set of good bags to eliminate one hole. Any powder visible outside the cage to the tube sheet indicates a poor bag seal. Powder inside the bag indicates a hole.
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