In 2007, the EPA mandated that all new on-highway diesel engines must limit the emission of diesel particulate matter (PM). To comply with this regulation, OEMs incorporated diesel particulate filters (DPFs) as part of a comprehensive emissions control system. DPFs trap the diesel particulate matter (PM or soot). The PM collected is then oxidized to remove it from the DPF.
Now, more than 6 years later, the rear view mirror can teach us a lot that we didn’t know then. The new exhaust system with the DPF works great to remove the diesel particulate matter, but what we have found is that ash left behind from lubricants and engine wear is very damaging to the DPF if not removed.
DOING THE JOB
The good news is the DPF technology is performing its job well if given proper care. Now, as in 2009, no longer do big rigs belch black smoke with the stench of diesel fuel in their wake. In addition, DPF-equipped trucks run quieter. Clear evidence is building that the elimination of diesel PM into the air is having a positive effect on the health of drivers and all others who come in contact with diesel soot.
Many fleets were experiencing problems with their DPFs due to the lack of a maintenance program to care for the DPF. Without a proactive maintenance program, the only thing you can depend on is unscheduled downtime, increased replacement costs, and poor fuel efficiency. Experience has shown that without proper cleaning, the DPF will crack, sinter, melt, or just plain get plugged with soot or hardened ash plugs.
In 2009, many questions remained unanswered. Today, we have some answers.
What do we know now? The DPF technology is working. Ninety-eight percent of diesel particulate matter has been removed from the atmosphere. Diesel particulate has long been suspected of increasing the rate of lung cancers in drivers and diesel techs. The evidence is becoming clear that the DPF is removing a major health risk from all who work in the transportation, construction, and mining industries.
Does a clean DPF improve fuel efficiency? Many fleets are now reporting fuel efficiency gains from 3 percent to as high as 5 percent when their DPFs are cleaned regularly.
How often does a DPF need cleaning? In general, for heavy-duty trucks using low ash oil, the DPF should be cleaned once annually or every 150,000 miles, and even more frequently in severe-service applications. For medium-duty trucks, using low ash oil every 75,000 miles. These intervals can vary depending on application. Ash left longer in the DPF begins to set up and harden, making cleaning difficult. These intervals are based on the real-world experience of FSX from cleaning more diesel particulate filters than anyone in the world.
Improperly cleaned DPFs or filters not cleaned at regular intervals will most likely need to be replaced. DPFs that have been cleaned on a regular maintenance program will have increased reliability and durability, as well as reduced vehicle downtime with better power. A DPF should be inspected and verified suitable for reuse.
How can the DPF affect the resale price of a used truck? If a DPF is in poor condition, it will need to be replaced and that can add to the truck’s price tag. To avoid a disputed appraisal, never show up with a plugged DPF and soot blackened stacks (one sign of a failed DPF). Also have on hand cleaning documentation showing proof of annual cleaning with inspection notes showing restriction before and after each cleaning.
Should the diesel oxidation catalyst (DOC) be cleaned along with the DPF? We recommend 5 minutes of a Stage 1 pneumatic blowout for the DOC.
When should a fleet own a DPF cleaner versus contracting the cleaning with an outside service? It’s been our experience at FSX that it is more cost effective to own a DPF cleaner rather than contract with a DPF cleaning service when a fleet has at least 100 DPF-equipped trucks. Such a fleet would pay for the equipment in about 1 year. The return on investment goes up from there.
What happens when DPF cleaning is ignored altogether? The cells inside the DPF fill with ash. The ash hardens and eventually the DPF plugs, cracks, glazes, or melts, and that destroys the DPF. That, in turn, results in vehicle downtime and added expense. OEM replacement filters cost around $3,000. This makes cleaning or exchanges of the DPF the best option for most truck operators.
What DPF cleaning tool should I buy? DPF cleaning systems have been in use for years now and there is a variety to choose from. Do your homework. Key things to keep in mind include: Is the DPF cleaner OEM tested or recommended? What is the method of cleaning (high pressure pulse or air knife)? What is the air compressor size and CFM/PSI rating? The more powerful the compressor, the more effective and thorough the cleaning. Is the DPF cleaning process visible to the technician to catch any possible failures such as cracking? Remember. You get what you pay for! Careful attention needs to be paid to choosing a DPF cleaning service provider as well.
What is the future of the DPF? It is doubtful that DPF technology will become obsolete any time soon as many improvements are being made to diesel emission control systems. Developments include thinner ceramic substrate walls for backpressure reduction, changes in microstructure, and porosity of the ceramic media to improve filtration efficiency. Many more improvements are in the works.
THE BOTTOM LINE
Diesel-powered engines will be an essential part of day-to-day life on this planet for decades to come. So will the DPF. But even with technological advances to this device, it will only function as designed if it is well maintained. ■
For More Information:
For more information about DPF cleaning, contact FSX Equipment at 360.691.2999, or visit www.fsxinc.com.
Modern Contractor Solutions, March 2014
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