Trends in Pleated Cartridge Filters (continued)

Filter Configuration

In a standard cartridge filter, the pleated media is formed into a long cylinder and sealed at the top and bottom with end caps. Dust collects on the filter's outside surface and, during cleaning, is dislodged by a burst of compressed air blasted into the filter's interior. By knocking the dust off the filter's exterior, this reverse pulse of air cleans the filter so that it can filter more air.

One problem with a standard cartridge filter, whether mounted horizontally or vertically, is that a significant portion of the cleaning energy is wasted in pulsing the cartridge's bottom end cap, as shown in Figure 3a. Cartridge filters have recently been designed with an internal structure, such as a cone or barrel, made of pleated media (usually the same media as that in the outer layer) and with a bottom hole rather than an end cap.

Figure 3 - Air distribution during pulse cleaning

This allows the filters to use the pulsing energy that otherwise would have been wasted pulsing the bottom end cap and distribute the cleaning air more evenly through the filter, as shown in Figure 3b. The result is a lower pressure drop, requiring fewer cleaning pulses. The filters also prevent re-entraining the dislodged dust. As each cleaning air pulse comes out of the internal cone or barrel, it flows straight down into the collector's hopper. This forces lightweight dislodged dust particles into the hopper and out of the incoming dirty airstream instead of pushing the dust toward the other filters during the pulse.