october2021 - 38

SPOTLIGHT ON FLUID & FILTRATION
» It is important to keep
DEF clear of impurities
and contamination
to avoid issues.
Nixxphotography | 488280729 | Getty Images
Dealing
with dirty
Best practices to
help fleets preserve
the purity of their
diesel exhaust fluid.
By Gregg Wartgow
DEF
T
he American Petroleum Institute (API) has been
licensing DEF (diesel exhaust fluid) since 2009,
and despite its longtime existence, DEF continues
to cause some issues for fleets.
" DEF is highly sensitive to impurities and
contamination such as chemicals, coolants, engine
oil, and water, " said Cornelius Jones, regional technical
expert for transportation at Shell Lubricants,
a company which produces diesel exhaust fluid,
along with engine oils and other lubricants. " DEF is
also corrosive to certain metals such as steel, iron,
zinc, nickel, copper, aluminum, and magnesium. "
As Jones pointed out, DEF contamination can
occur during any of the following:
ÜAccidentally mixing DEF with diesel fuel
ÜNot using a DEF-dedicated pump, hose, and
nozzle
ÜNot using a DEF-dedicated storage container
ÜUsing a container made of one of the above-mentioned
metals
" DEF is manufactured from an automotive/
medicinal grade of urea dissolved in deionized
38 Fleet Maintenance | October 2021
water, " explained Jay Gagnon, senior product
manager for BlueDEF diesel exhaust fluid and
dispensing equipment at Old World Industries. " The
solution must contain 32.5% urea and 67.5% water. "
That sounds relatively simple, but there is more
complexity to DEF than those two basic ingredients.
And with complexity comes more opportunity
for human error.
" The standard behind DEF is a 'purity' spec, "
said Jeffrey Harmening, a manager with the API
whose areas of responsibility include engine oil
and DEF. " There is actually a lot more to DEF than
just urea concentration. There are roughly 15 other
physical and chemical properties that are essential
to maintaining DEF quality. "
Problems when purity
is compromised
The bottom line is that technicians and drivers
should pay close attention to DEF purity. If the
purity level doesn't meet the proper specification
(ISO 22241), Harmening said a fleet could run into
issues like deposit formation, corrosion, catalyst
blockage, and injector or filter clogging, which will
affect dosage rates. When dosage rates are affected,
the aftertreatment system's ability to reduce
NOx is impeded and sensors may trip. All of this
can lead to increased downtime and costly repairs.
One sign of potential DEF contamination is poor
engine performance. A fault code can also light up
the malfunction indicator lamp. In extreme cases,
the engine will go into a derate mode. " Then the
fleet may have to send the vehicle into a dealer
for the DEF system to be cleaned, " Gagnon said.
" Worst case, replacement of expensive system
components may even be necessary. "
Catalyst fouling is another possible byproduct
of dirty DEF. Deposit buildup has long been
a challenge with many DEF products. For fleets
capitalizing on the growth in last-mile delivery,
that challenge has only become greater.
" In sub-optimal operating conditions, deposit
formation can negatively impact exhaust system
durability by the formation of solids (cyanuric acid
october2021

Table of Contents for the Digital Edition of october2021
