DPFs Unplugged

by James Menzies

TORONTO, Ont. –As the calendar flips to 2010, you could be forgiven if you find yourself thinking more about DEF than DPFs.

The first engines in North America requiring diesel exhaust fluid (DEF) are now hitting Canadian highways and customers will soon be seeking out suppliers of the urea-based solution required for engines using selective catalytic reduction (SCR). But that’s a topic for another day. In the meantime, diesel particulate filters (DPFs), which will remain a fixture on all 2010 highway trucks, will be coming due for their first cleanings.

DPFs were introduced by all OEMs in response to the EPA07 emissions standards that called for a reduction in particulate matter (PM). The filters trap PM and burn it off at high temperatures, usually passively and transparently while the truck is rolling down the highway.

By all accounts, the filters have lived up to manufacturer promises of lengthy cleaning intervals, with many still functioning at 400,000 kms or more -well beyond the 150,000 mile (240,000 km) minimum required by the EPA.

But that’s not to say they’ve been without their problems. Kevin Beaulieu, supervisor of fuel efficiency with Bison Transport, said his company has encountered problems with injector failures triggering DPF regenerations more frequently than required, “causing the things to want to regenerate several times daily, which takes a huge toll on fuel economy.”

Even so, Bison has yet to require a large-scale cleaning or exchange (and incidentally, the fleet never did make the transition to CJ-4 engine oils, which some oil companies insisted would be necessary to avoid premature clogging of the filter).

Now that the first of Bison’s EPA07 engines are approaching the 400,000-km mark, the company is beginning to evaluate its DPF cleaning and replacement options. Having been quoted as much as $500 per exchange through local vendors, the company is staring at an enormous expense, causing it to consider purchasing its own DPF cleaning equipment.

“With the number of units we have in service, it wouldn’t take very long to have a payback on our own machine, even if it’s centralized in one location and we ship to other terminals,” pointed out Itamar Levine, director of fleet assets with Bison Transport.

But DPF cleaning machines don’t come cheap, making them infeasible for most small fleets and certainly owner/operators. And even large fleets may have to factor in the cost of upping the voltage of their facilities and training staff on the use of the machines if they wish to implement an in-house cleaning program.

“That’s very expensive,” pointed out Tom Nelson, sales rep for DPF Cleaning Specialists, a new Windsor, Ont.-based company that offers DPF cleaning services in southern Ontario. “It could be $75,000 or more just for set-up.”

Truck and engine dealers have been launching simple cleaning and exchange programs that minimize the downtime and disruption for fleets and owner/operators.

“For Volvo, the recommended procedure is to simply have your Volvo dealer swap out the DPF core and replace it with a remanufactured core,” Volvo spokesman James McNamara explained. “This is the same procedure as today and can be done during the course of an oil change. The used cores are then shipped to our remanufacturing centre where they are restored to greater than 90% of their original efficiency. This way dealers and customers avoid the expense and bother of purchasing or operating a core cleaning system.”

Cummins also offers a while-you- wait DPF cleaning service as well as an exchange program in which a customer can swap their DPF for a ReCon Particulate Filter.

“The ReCon exchange program is the simplest and most time efficient process for getting the customer back on the road quickly,” suggested Christy Nycz, on-highway communications manager with Cummins. She added more than 125 Cummins distributors and many dealers have been equipped with DPF cleaning machines.

“We are confident that the service network is sufficiently prepared to accommodate customers’ service needs as they approach the first needed cleaning interval for DPFs,” she said.

While all engine suppliers are now offering convenient cleaning and exchange programs, the cleaning methods do vary. Cummins uses a pulse-air cleaner which produces pulses of air that remove excess ash from the filter, Nycz explained. Detroit Diesel, on the other hand, uses a proprietary “de-ionized water technology” to restore filters to 95% of their original capacity.

A third option for truck operators is to seek out the services of a company specializing in the cleaning of DPFs or a specialized exhaust shop that offers DPF cleaning.

DPF Cleaning Specialists, is a recently-formed company that serves the Detroit-Toronto corridor. Nelson said the company was set up to provide a convenient option for customers who wanted to continue using their own filter.

DPF Cleaning Specialists visits the fleet or owner/operator, picks up the filter (the customer must remove it and reinstall it afterwards), cleans it overnight and returns it the following day. It also applies a serial number to each filter and creates an online service record so fleets can monitor the cleaning history and mileage of each of their DPFs. DPF Cleaning Specialists encourages fleets to stock one or two additional filters so they can simply swap them out for cleaning and further reduce downtime.

The cost of a straight cleaning is about $300 per filter (with volume discounts available to fleets) including pick-up and delivery within southern Ontario.

“The big thing is, you’re getting your own filter back,” Nelson said. “On an exchange program, you’re getting another filter and you don’t know what you’re getting. You could be getting somebody’s problem.”

DPF Cleaning Specialists uses the high-end FSX cleaning machine and also inspects the filter for damage.

If the filter’s excessively clogged due to a blown turbo or other malfunction, it may need to be baked for eight to 12 hours in a kiln, which will add to the cost of cleaning. The company says its cleaning techniques restore the filter to 97-98% of its original capacity. DPF Cleaning Specialists can be reached at 877-373-2580 or found online at www.dpfcleaningspecialists.com.

Whatever option you choose, it’s a good idea to watch for signs the DPF is losing its effectiveness and get it in for a cleaning sooner than later.

“Lots of people are realizing that if you maintain the filters, you’ll have them forever. If you don’t maintain them, you’re going to have problems,” Nelson said.

If the DPF begins regenerating more frequently than usual, Nelson said that’s a good sign the filter’s due for a cleaning.

This could come earlier than expected in certain applications which aren’t conducive to passive DPF regeneration events, such as in regional P&D or municipal duty cycles.

“Generally, the sooner you get to them the better. Get them

THE IN-HOUSE SOLUTION: Big fleets may want to consider buying their own DPF cleaning machine like this one, but they cost five figures and may require power upgrades and technician training.

cleaned at around 200,000 to 250,000 miles (320,000-400,000 kms) and keep them clean and you’re not going to have problems with them,” Nelson added.

“If you don’t, as soon as it starts creating backpressure -that can lead to a whole host of problems.”

Darry Stuart, president of DWS Fleet Management and one of the hosts of the Technology and Maintenance Council’s popular Shop Talk forum, pointed out it’s also important to inspect and clean the DPF following engine problems.

“If there’s an engine failure of any kind, such as an injector or turbocharger failure, the DPF should be pulled, checked and cleaned,” he advised.

Otherwise, he said, it may not function properly down the road.

Stuart said DPF cleaning intervals have been a hot topic at the TMC o
f late, but there’s still no sound data related to when they should be pulled for their first cleaning.

The one thing that is known, however, is that they’ll all need to be cleaned at some time or another, so it’s a good idea to explore your options early and determine which approach is the most practical and cost-effective for your own operation.

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