DPFs

Diesel particulate filters, commonly abbreviated as DPFs, are exhaust aftertreatment devices designed to remove particulate matter from diesel engine exhaust. They are installed in the exhaust stream and trap soot and other fine particles, reducing emissions of diesel PM that can affect air quality and human health.

Most DPFs use a porous ceramic or metallic substrate, often with a honeycomb structure. The walls may be coated with catalysts to promote oxidation of collected soot during regeneration. Filtration efficiency is high for soot particles within the size range produced by diesel combustion, and many designs are engineered to withstand high exhaust temperatures and pressures.

Regeneration is the process by which the accumulated soot is burned off to restore the filter’s capacity. Passive regeneration occurs automatically when exhaust temperatures are high enough, typically during sustained highway driving. Active regeneration temporarily raises exhaust temperature or injects additional fuel to promote soot oxidation, and may be initiated automatically by engine control systems or vehicle diagnostics.

Sootful ash contents accumulate in DPFs over time, and while soot can be burnt off during regeneration, ash from lubricating oil and additives does not burn and gradually fills the filter. Periodic ash cleaning or DPF replacement is often required as part of maintenance.

DPFs are a central component in meeting modern diesel emission standards and are common in on-road passenger and commercial vehicles as well as many off-road applications. They are monitored by vehicle diagnostics and may trigger regeneration cycles and fault warnings if backpressure or temperature conditions indicate clogging or failure.