My Homepage

Diesel Particulate Filters (DPF) as well as the Environment

Diesel Particulate Filters (DPF) as well as the Environment

Reducing diesel soot emissions by 80%:

Changes to new automobile emissions legislation scheduled for 2009; the 'Euro 5' standards, will make particulate filters as commonplace in diesel automobile exhausts as catalytic converters are on petrol automobiles.

The goal is an 80% decrease in diesel particulate (soot) emissions, but the technology's not without problems; roadside assistance patrols are already being called to autos with the particulate filter warning light illuminated, which generally indicates a partial blockage of the DPF filter.

Clearly, changes to styles that were driving could be demanded from these emission-reducing systems for maximum gain.

How do the filters function?:

Diesel Particulate filters (DPF) or 'traps' do only that, they catch bits of soot in the exhaust.

As with any filter (think of the bag in your vacuum cleaner) they need to be emptied frequently to preserve operation. For a DPF this procedure is called 'regeneration'; the accumulated soot is burnt off at high temperature to make just a miniature ash residue. Regeneration might be either active or passive.

Passive regeneration

Passive regeneration takes place automatically on motorway-sort runs when the exhaust temperature is high. Many cars do not get this sort of use though producers have to design-in 'lively' regeneration where the engine management computer (ECU) takes control of the procedure.

Active regeneration

It needs to be possible to begin a whole regeneration and clear the warning light simply by driving for 10 minutes or so at speeds greater than 40mph.

If you keep driving in a relatively slow and blow off the light, stop/start pattern soot loading will continue to build up until around 75% when you are able to expect to see other dashboard warning lights illuminate also. At this point driving at speed won't be adequate and the automobile will need to go to a dealer for regeneration.

Expensive repairs:

If warnings are still dismissed and soot loading continues to raise then the most likely outcome is going to be a new DPF.

Chiefly town based driving:

If your own automobile use or lease auto use is largely town-established, stop/start driving it would be a good idea to decide on petrol instead of risk the hassle of DPF regeneration that is incomplete.

DPF additives:



The most typical kind of DPF is found quite close to the engine so that passive regeneration is possible, where exhaust gases will still be relatively hot and features an integrated oxidising catalytic converter.

There is not consistently space how to clean diesel particulate filter near the engine though so some makers utilize an alternate kind of DPF which relies on a fuel additive to reduce the ignition temperature of the soot particles in order that the DPF could be located farther from the engine.

The additive is stored in a separate tank and is automatically mixed with the fuel whenever you fill up. Tiny amounts are demanded so a litre of additive should treat around 2800 litres of fuel, enough to cover 25,000 miles at 40mpg.

You should not detect anything other than perhaps a puff of white smoke from the exhaust when the procedure is finished.

AA experience:

The AA has seen evidence of DPF systems failing to regenerate - even on automobiles - that are used mainly on motorways. Their conclusion is the fact that on automobiles with a very high sixth gear engine revs are excessively low to produce adequate exhaust temperature, but occasional harder driving in lower gears ought to be enough to bum off the soot in such cases.

Examine the handbook:

Should you buy or lease an automobile with a DPF fitted it is vital that you read the pertinent section of the vehicle handbook so you realize precisely what actions to take if the warning light illuminates and how, if at all, your driving style may have to be corrected to ensure maximum DPF efficiency and life.