What-is-a-DPF.jpg A diesel particulate filter (DPF) removes particulate matter from diesel exhaust by physical filtration. Many filter types are available but the most common type is a ceramic (cordierite or silicon carbide) honeycomb monolith.

The structure is like an emissions catalyst substrate but with the channels blocked at alternate ends. The exhaust gases must therefore flow through the walls between the channels and the particulate matter (PM) is deposited on the walls.

The filtration efficiencies of diesel particulate filters is >99% for solid matter. Since diesel particulate matter has a non-solid portion, the total efficiency for this is lower than this >90%.

All particulate filter systems include some means of Regeneration.

Filter Regeneration

Filter Regeneration

Any filter has a finite capacity. Diesel particulate filters (DPF) must be cleaned out, intermittently or continuously, if they are not to block.

Passive systems

Passive systems

The Continuously Regenerating Trap (CRT®) system is the most widely used Diesel Particulate Filter (DPF) system in the world and is a patented Johnson Matthey technology.

Active Systems

Active Systems

Any application, in which it cannot be guaranteed that the exhaust gas conditions will be suitable for a passively regenerating system, will require some active regeneration.