DieselEmissionsInsider2024 - 9

DIESEL EMISSIONS
Inspection bench uses industry standard
flow rates to determine flow efficiency.
Voltage configuration can vary based
on your needs. Process requires high air
throughput of 100 cfm. These machines
are typically seen in larger repair shops
and dealerships.
Turbos, EGRs, & Charge Air Coolers:
How Do They Affect DPFs?
By: Mark Taylor, NARSA/IDEA Executive Director, mtaylor@narsa.org
Aqueous cleaning method is fairly
new to the US market. The process of
washing filters is not new technology but
not common either here in the United
States. The aqueous machine is fully
self-contained and uses a surfactant to
encapsulate the soot to allow it to be easily
removed from the filter. The wash cycle
varies based on size, but average cleaning
time is 20 minutes. This machine will
allow you to clean pretty much any filter
configuration. It operates on standard 208,
240v power.
Any time you get a filter wet, you have to
dry them. The industry standard time for
drying filters is 4 to 6 hours. Filtertherm
aqueous cleaning process washes and dries
filters in 2 hours. There are many aqueous
cleaning machines and the difference you
will find is the process time and cost.
It requires no air and is found in a wide
range of facilities from auto repair shops
to dealer-level shops. This process has its
limitations as well. It should not service
oil-soaked DPF.
This article was originally featured as an IDEA
" Lunch & Learn " webinar. All of our webinars and
previously recorded presentations are available
for NARSA/IDEA members on our website
http://narsa-idea.org
GREAT SERVICE BUSINESSES understand
the value they can be to their customers
when they can offer guidance and advice
when servicing different parts found on
a truck. Just like the radiator specialist
being asked about overheating engines
or premature radiator failure, the Diesel
Particulate Filter (DPF) cleaning company
will inevitably be asked about the exhaust
system of a diesel engine. Your team must
be educated about diesel emissions so
they can offer that value added to your
customers. Not every occasion a DPF is sent
in for a cleaning will it be necessary to offer
your guidance, but when the time does arise
you will want your team to be prepared.
By being able to speak intelligently about
the diesel exhaust system, your people
can be a resource for your customers. In
some businesses, the technician cleaning
the diesel particulate filters is one of the
least experienced people in your shop. To
help them better understand the process,
let's do a simple review of how the diesel
engine operates and the components
that control and or create the exhaust.
Understanding that the diesel particulate
filter is just a trash can and only catches
what comes down the exhaust pipe is the
first step in understanding the process.
Understanding the Process
Let's start at the beginning to help better
understand the process. A simple review
of how the diesel engine operates and the
components that control and or create
the exhaust will allow your entry level
technicians to grasp the basic concepts.
The 4-cycles of a 4-cycle diesel engine are
intake, compression, power and exhaust.
As the piston moves during each stroke, it
turns the crankshaft. Air is drawn through
the intake valve of an engine on the down
stroke of the piston (1st cycle), next that
air is compressed by the upstroke of the
piston at a very high compression ratio to
cause the heat needed to combust diesel
fuel (2nd cycle). Near the very end of the
compression cycle fuel is injected (the
timing of the fuel injection is controlled
electronically on all engines with DPFs)
into the cylinder, combustion occurs
(power) and pushes the piston down (3rd
cycle). The exhaust stroke (4th cycle) is
the final phase, the piston moves upwards,
squeezing out the gasses that were created
during the combustion stroke through
the exhaust valve and into the exhaust
manifold. The exhaust in the exhaust
manifold enters the turbo which is bolted
to the exhaust manifold. At the same time
a precisely measured amount of exhaust
gas is recirculated through the exhaust gas
recirculation cooler which is mixed with
fresh air from the charge air cooler, and
the process of injecting air into the engine
continues. This entire process happens
anywhere from 800 to 2,000 times per
minute depending on the Revolutions Per
Minute of the engine so the flow of exhaust
is constant.
Note: On a gasoline powered 4-cycle
engine an air/fuel mixture is drawn in
during the first cycle, it is compressed at a
much lower ratio during the second cycle
and then a spark plug ignites the air fuel
March/April 2024 | DIESEL EMISSIONS INSIDER | 7
http://www.narsa-idea.org
DieselEmissionsInsider2024

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