Fleet Maintenance - 21

Ü Inspect external hardware and connections
every six months.
Ü Conduct regular visual inspections of
components.
For more guidance on DPF maintenance,
the Technology & Maintenance Council (TMC)
offers their Recommended Practice (RP) 355,
Maintenance and Inspection Guidelines for
OEM-installed Exhaust Particulate Filters for
Diesel-Powered Vehicles. TMC RP 355 covers
information on DPF function, performance, diagnostics, maintenance, and cleaning. TMC advises, however, that this RP should not replace the
engine's OEM recommendations for maintenance
and cleaning.
Overall, proper care and maintenance of all
aftertreatment system components as well as
following OEM guidelines will help ensure a properly functioning DPF.

The DPF is then put into a blast cabinet where any loose ash and particulate matter are blown out.
Photo courtesy of Clean Diesel Specialists

After the air blast, the DPF is blasted with
water to further remove ash and
particulate matter.

Photo courtesy of Clean Diesel Specialists

Next, the DPF is put in an oven to bake
any remaining particulate matter into ash,
so it is easier to remove. This step is about an
8-hour process, from heating the oven to
cooling the DPF. To finish off the cleaning
process, the filter is air-blasted a second time,
then weighed and flow rate tested to ensure
the DPF is as clean as possible.

Photo courtesy of Clean Diesel Specialists

Cleaning methods
When it comes to cleaning a DPF, fleets have a variety of options available for cleaning methods, such
as pulse cleaning, thermal cleaning, and liquid
cleaning. Each fleet or DPF cleaning specialist will
have their own method for cleaning. Currently, no
standard exists specifying what a "clean" DPF is,
which leaves room for misinformation to spread
on "proper" cleaning for DPFs.
In order to help combat any misinformation,
TMC has passed a new RP, RP 374, for Cleaning
Diesel Particulate Filters and Diesel Oxidation
Catalysts. Bruce Balfour, vice president of Clean
Diesel Specialists, and Wayne Juchno, executive
director for the National Automotive Radiator
Service Association, were the co-chairs for the RP
on the TMC S.3 Engine Study Group. They wanted to set a standard on DPF and DOC cleaning to
educate fleets and technicians on the proper way
to clean and test the filters.
"There [are] a lot of myths and bad information
on how to clean filters such as steam cleaning or
pressure washing the filters," Balfour says. "Yes,
it will clean the filter, but it's also going to wash
off the coatings and damage the substrate as
most steam cleaners or pressure washers operate
between 1,200 to 4,000 psi."
TMC RP 374 offers information on methods
for cleaning, testing, and documenting maintenance on OEM and aftermarket DPFs and DOCs.
Though again, this RP is not meant to replace OEM
recommendations for cleaning. Practices such as
knowing when to clean the DPF can vary.
"It really depends on the application," says
Jeremy Anderson, national sales manager for FSX
Equipment, a provider of filter cleaning systems
and services for cleaning DPFs and industrial
filter cartridges. "It varies widely depending on
the engine and the duty cycle and ... sometimes
on the operator and how they drive the vehicle.
Every fleet is going to have their own sweet spot,
so to speak, when it comes to maintaining [the
DPF] properly."
For on-highway vehicles, the DPF should be
pulled off for its first cleaning after 150,000 to
200,000 miles, and then every 100,000 miles
after that for preventive maintenance cleaning,
Anderson notes. Though for severe duty applications, like sweepers or garbage trucks, those DPFs

May 2020 | VehicleServicePros.com

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Fleet Maintenance

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