FAQ: Does a dust buildup or “dust cake” on dust collector filters indicate that the system is not working properly?

Some people worry that their dust collection system is not performing properly when they open the collector and see dust on the filters. It is just the opposite: A controlled level of dust on your filters actually improves the filtration efficiency by helping to filter out more dust particles, thereby extending the life of the filters.

A dust collector automatically pulse-cleans its filters using very brief bursts of compressed air that blow the dirt off the filter surfaces and down into a collection device. Most dust collector control panels offer a choice of three pulse-cleaning methods:

1. Continuous pulsing describes a dust collector that pulses at a set time period – for instance, every 10 to 15 seconds. Sometimes this method is absolutely required, but this pulse-cleaning method uses the most compressed air over the life of a dust collector and is very costly.
2. On-demand pulsing only activates the cleaning system when the collector’s pressure drop reading goes above a preset high set point and pulses back to a preset low point on the collector’s control panel. This method typically conserves on compressed air as the collector only periodically pulses. In addition, most dust emissions pass through a filter when the reverse pulse occurs in a dust collector, so fewer pulses will equal low dust emissions for most dust collectors.
3. Downtime pulsing is used while the dust collector fan is not running. Using downtime pulsing reduces dust re-entrainment and will return your filters to their lowest possible pressure drop reading.

To maintain a controlled dust cake on filters, it is recommended that you pulse your dust collection system as little as possible – avoiding continuous pulsing unless absolutely necessary. This approach will also save on compressed air, reducing the total cost of ownership to operate your dust collection system. Your manufacturing plant probably has a value placed on compressed air and you understand that excessive compressed air usage gets expensive.

If filters become totally blinded by heavy dust buildup, and/or the pressure drop reading has reached a level higher than the filter manufacturer’s recommended limit, it’s time to change the filters. However, even if this situation has not occurred, it’s a good idea to replace filters every two to three years at longest. An older filter may develop a hole or leak after time and will no longer deliver the guaranteed efficiency.

Request/download a comprehensive white paper on dust collector filter selection here.