THE DPF AND YOU

How do I get more hours out of my DPF?

The majority of DPF systems rely on exhaust gas temperature to bake the heavy dense oily soot into ash. If an operator is experiencing an undesirably low number of hours from their DPF before they are receiving notifications of high back pressure or low power, then some of the causes can be:

• Insufficient exhaust gas temperature - most DPF systems require around 600° F (320° C) to start regenerating the soot into ash

• Insufficient time as a high enough temperature - some engines will reach regen temperature, but their work cycle means that they only reach that temperature for short periods of time. Typically, a DPF will need 8-10 minutes at a temperature above 600° F (320° C) to fully regenerate the soot to ash.

• Not reaching regen temperature often enough. Some engines reach regen temperature during their work cycle however not often enough. For some equipment there may be long periods of time spent traveling to the work site or extended periods of time idling due to climate (cold weather) or waiting for work

• Excessive soot loading - some engines can produce undesirable levels of soot because of
• Poor engine maintenance
• Incorrect fuel/air mixture ratio 
• Altitude - diesel engines operating at high altitude can produce high soot levels due to the lower air pressure affecting the fuel/air ratio

If a DPF is working optimally it is possible to run for several thousand hours before needing to service the DPF (clean the filter). If there is not a desirable work cycle it is likely that the DPF will be producing high back pressure in 30 - 40 hours or less.

What is a good number of hours to run before cleaning my DPF?

Operators of equipment will want to run their machine for as long as possible without having downtime due to needing to service their exhaust aftertreatment system. In the same way that we service our engines by changing air filters, oil filters, or fuel filters, the DPF needs servicing also to ensure maximum life. While it may be possible to go thousands of hours without servicing the DPF, if the work cycle is high enough this can cause the ash residue in the filter to become very impacted. The constant heat and moisture in the exhaust will cause the ash to bake into the filter. This impacted material then becomes almost impossible to clean out of the filter. While some OEMs suggest cleaning the DPF around 5000 hours, we have found it is better to clean the DPF around every 2000 hours. Some lower work cycle engines may only get 250 - 500 hours between servicing as they do not generate sufficient exhaust gas temperatures to ensure regular regeneration within the DPF.

Can I put a DPF on any diesel engine?

Yes - a DPF can be installed on any diesel engine. There are however several factors that will affect their performance. Almost all wall flow DPF filters will capture 95% - 99% of the diesel particulates whether the engine is running hot or cold. The question should really be “how many hours do I want to get from my engine before I’ll need to service the DPF?” The main thing that a DPF will require to get the maximum number of hours between cleanings is exhaust gas temperature. The hotter the engine runs, the more ability the DPF will have to regenerate the soot into ash. Small, naturally aspirated engines tend often to run cool and not produce enough temperature to effectively regenerate the soot. Turbocharged engines will tend to run hotter. Many sites will implement a no-idle policy to ensure better performance from the DPF’s on their equipment.

What can I do to make my DPF run better?

Run it for hotter, more often, for longer periods of time. All DPFs require heat to regenerate the soot into ash. Stop-and-go runs with minimal load on the engine are the worst thing possible for a diesel exhaust aftertreatment system. Engines running at low load or idling have a poor fuel/air ratio meaning that they produce more diesel particulates and therefore will load the filter sooner. This coupled with the low engine heat will mean that regeneration of the soot into ash will not happen very often meaning that the filter will plug up quicker. Most passive DPF systems will require exhaust gas temperatures of 320° C for around 8 - 10 minutes more often than not to work best and achieve maximum number of hours between cleanings. The same runs true for many of the active DPF systems. These systems rely on passive DPF regeneration most of the time and just use their ability to do a ‘forced regen’ as and when required.