When selecting an industrial dust collector, it's important to consider more than the machine itself. It’s important to look at inside components that are crucial to dust collector performance and have to be periodically replaced. Filter cartridges are to a dust collector like printing cartridges are to a laser printer. They are consumables that greatly impact the dust collection system's efficiency, and they differ widely from brand to brand. You need to consider filter design, pleat design and filter media when selecting the best dust collection system for your application.

Conventional designs

The industry's first bag-houses and cartridge dust collectors used filters that were positioned horizontally  to overcome the upward can velocity effects that sometimes occurred. Air would enter the hopper and then travel up into the filter housing. Can velocity is the airstream velocity in the passage area between the installed filters. To clean the dust off of the filters, the flowing air had to be slow enough to allow the dust to fight back down through the air stream. This system worked well for heavy dusts, but did not work well for light dusts like weld smoke and fumed silica. Designers deduced that if the filters were configured horizontally, the clean air plenum would move to one side of the collector, expose the dirty air plenum to the top, and bring the air into the top of the dust collector. This resulted in a downflow effect that helped overcome the upward can velocity issue.

However, laying a filter on its side presents many limitations. The key issue is that the dust remains on top of the filters because it can't get effectively pulse-cleaned off. The dust blinds at least one-third of the entire filter, increasing the air-to-media ratio in the collector and causing premature failure of the filters.

Another major issue with collectors using horizontal-style cartridges is that 100 percent of the incoming dust is dumped on top of the filter cartridges. There is no chance to pre-separate heavy and abrasive particles from the air stream before they come in contact with the filters. This is also a major problem because any spark entering the collector will end up on a filter cartridge, increasing the risk of a combustible dust explosion or fire.

A vertical solution

Designers worked to develop filters without the conventional problems associated with horizontal cartridges...dust piling on the top and dust falling onto the filters below on the way to the hopper. Vertical-style filters provided a good solution because they are able to pulse dust particles straight into the hopper instead of onto other filters in the collector. With each pulse of compressed air, the dust and debris is ejected out of the filter cartridges, and gravity pulls it down into the hopper.

Having filters installed vertically and having the entry inlet positioned so that air flows into the side of the collector prevents upward interstitial can velocity. Without this velocity, filters last longer. Dust enters the inlet of the dust collector at the same height as the cartridges. The air then travels through a series of staggered channel baffles that distribute the air. the baffles also act as a classifier, preventing larger particles from reaching the filter cartridges. Instead, they drop straight into the hopper. This cross flow effect eliminates upward interstitial can velocities. Since the air is brought into the collector at the cartridge level, air no longer flows upward towards the filters. The system combines the advantages of a downflow-style air pattern and vertical filter placement.

Vertical Filters Paired with HemiPleat Gold Cone Technology

A vertical filter cartridge design makes it easier to load and change-out filters. Installation is even easier with the easy grip rectangle pan on the HemiPleat Gold Cone filter. In addition, HemiPleat filters stay cleaner and lasts longer than conventional pleated filters because they use a pleat design that exposes more media to the airstream. This means that more dust is loaded onto the vertical filter and released during pulse cleaning. Compare that dust loading with horizontal filters that can be up to 20 percent blocked due to buildup on top of the filter media.

Dust collectors using a vertical filter installation, a cross flow inlet and HemiPleat filter technology deliver unparalleled performance and efficiency while maintaining a low pressure drop. Filter efficiency translates to lower energy costs and longer filter life.

For more information on containing dust and fumes in your facility, contact a Camfil APC product expert.