Diesel Particulate Filters

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What is a Diesel Particulate Filter?

Diesel Particulate Filter working; MECA.org

DPF process from MECA

Diesel Particulate Filters (DPF) (called scrubbers in the past) are a porcelain-like filter that replaces the muffler in most applications. DPFs are not flow-through; they force the exhaust to pass through the walls of the core material and are able to filter out up to 90% of all the particles in the exhaust. As the diesel particles get caught in the filter, they create a restriction which increases back pressure. To reduce the material in the filter, lower the back pressure and extend time between

DPF Substrate inlet face

cleanings, filters incorporate a “regeneration cycle” that reduce the soot down to ash. The regeneration cycle should not be confused with cleaning. Cleaning the ash from the filter must still be completed on all types of DPFs on a routine maintenance schedule, usually annually. This regeneration cycle occurs inside the filter core (substrate) by high heat that burns the soot much like a cigarette burns. This regeneration process is where most of the manufacturers differ in their approach. The two processes types are passive or active. Choosing between DPFs with passive or active regeneration systems does not have an impact on how much particulate matter is removed from the exhaust.

Passive regeneration: By coating the inlet-side of the filter with a catalyst (precious metals) the soot can be reduced by using the vehicle’s own exhaust heat. For optimum performance, Engine Control Systems currently recommends using this DPF type with engine exhaust temperatures that hit the 280 degree Celsius range for at least 25% of the duty cycle. If the engine does not reach these temperatures, then the filter will clog on a regular basis and will have to be removed and regenerated on a cleaning machine that has heating capabilities. Engines that want to use this technology must first have temperature data loggers installed to measure the exhaust temperature for 3-5 days to verify the product will work. This is required by CARB and most of the manufacturers. These passive DPF systems are more economical than active regeneration DPF types, and usually cost around $12,000-$18,000, depending on the engine size.

Combination FilterActive regeneration: In order to reduce the soot into ash, a heat source can be actively started by the operator or maintenance personnel while the engine is not running. Their primary difference from passive regeneration systems, with regard to application, is that active regeneration DPFs do not have minimum temperature requirements. There are currently two methods verified by CARB, diesel-fired heaters and electrically powered heaters. Diesel-fired units generally cost around $14,000 to $25,000 for single systems (dual systems can be twice as expensive). Electrical units cost around 12,000-$20,000 installed. Electrically powered units require a high-voltage, land-based structure that have additional infrastructure costs associated with them.

Passive DPF retrofit by ERG

PLEASE NOTE: This summary is for informational purposes only, and the data and figures provided may change at any time. If you would like a more detailed description of these product choices, or if you would like the most current information, we encourage you to contact us by phone or e-mail.