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How our Diesel Particulate Filter (DPF) works.

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How our Diesel Particulate Filter works:

Once the hot exhaust leaves the engine, it passes through the turbocharger, after which it travels through the exhaust pipes to the Diesel Particulate Filter (DPF). The exhaust contains microscopic soot particles, which are trapped and consumed by Volvo's DPF. The DPF system also acts as a muffler.

There are two ceramic elements inside each of Volvo's DPFs. The first is a three-inch-thick oxidation catalyst. It changes some of the hydrocarbons in the exhaust into carbon dioxide and water vapor.

The second element is the particulate trap. It is a ceramic filter with a special metallic coating. The trap is about 12 inches thick and catches 90% or more of the soot in the exhaust.

The DPF system not only traps soot, it also consumes it, leaving behind a fine ash. It does this in a process called regeneration. Regeneration occurs in two forms, active and passive.



Volvo's DPF system has been designed to operate with a primarily passive regeneration cycle to optimize fuel economy. In passive regeneration, the soot is stripped out of the monolith by an ongoing catalytic reaction process that uses no additional fuel and is not noticeable to the driver. The catalytic reaction is driven by high exhaust temperatures.

The entire process-which typically takes place during high speed pulls-is simple, quiet, effective and fuel efficient. Volvo has engineered its DPF and exhaust systems to enable passive regeneration as much as possible.



Some truck operations, such as city pickup and delivery or refuse collection, do not generate consistently high enough exhaust temperatures to enable passive complete regeneration of the DPF.

In these cases, the DPF will periodically undergo active regeneration. In this process, a small mist of diesel fuel is injected into the exhaust stream at the turbocharger outlet; the mist travels through the exhaust pipe to wet the DPF's pre-catalyst. This causes a chemical reaction that raises DPF temperatures to the level required to convert the soot into CO2.

Active regeneration takes about 15 minutes and the operation is not noticeable to the driver. The process happens when sensors in the DPF alert the engine computer that the particulate trap is becoming full.

As with passive regeneration, a fine ash remains trapped in the DPF. The ash is easily cleaned out during routine maintenance service. Volvo expects the DPF to go for significantly more than 150,000 miles between cleaning.

- See more here.


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