These engineering changes brought
with them changes in the standards for
acceptable diesel fuel cleanliness
standards. With the higher fuel
pressures and tighter tolerances
required to meet the new emissions
standards, diesel fuel had to be cleaner
than ever for on-highway vehicles to
function properly. If even the smallest
dirt particles or other contaminants
were allowed into the engine,
catastrophic injector failure was not
just likely; it was probable. Efficient,
effective filtration became a must.
And now, the sea change has come
to off-road vehicles and equipment. In
2004, the US Environmental
Protection Agency signed the rule
introducing Tier 4 Emission
Standards, to be phased-in from
2008 – 2015. These standards require a
massive reduction of particulate
matter (PM) and nitrogen oxides
(NO
x
), and the subsequent changes to
the way engines are built are already
similar to those required by the
2007 – 2010 standards for on-highway
engines.
In short, without effective, precise
filtration both on and off the vehicle,
off-road operations will begin to see
significant downtime as onboard fuel
filters begin to plug quickly (at best) or
injectors begin to fail.
What you cannot see can
hurt you
Today’s Tier 4 engines use
high‑pressure common rail (HPCR)
fuel injection systems that operate
upwards of 40 000 psi. These systems
require very clean fuel to operate
as-designed for their entire service
interval (up to 20 000 hr in some cases).
Unfortunately, most fuel that is
dispensed from storage tanks into
equipment is hundreds of times dirtier
than what is recommended for many
injection systems.
Knowing that emissions standards
are ever-evolving globally, diesel
engine fuel system manufacturers
and filter manufacturers have
cooperated in research efforts at
Southwest Research Institute (SwRI)
to determine the level of filtration
required to protect these advanced
fuel system components from hard
particle damage.
“We see Tier 4 engines being more
and more sensitive to dirt and other
contaminants that can be picked up
by fuel as it makes its way from the
refinery to its eventual use,” said
Jim Doyle, Development Engineer
– Donaldson Clean Fuel & Lubricant
Solutions. Donaldson is a leading
worldwide provider of filtration
systems and a participant in this
research. “Just like the saying
‘garbage in, garbage outʼ, the same
holds true with fuels and lubricants. If
you put dirty fuel or oil into your
equipment, ultimately there will be
breakdowns that cost time and
money.”
But what is dirty diesel? Until these
new standards took effect, standard
ISO cleanliness tests could be used to
determine if diesel was clean enough
for use. But the SwRI research efforts
proved that this is no longer the case.
The most recent phase of these
research efforts was completed in 2011
and summarised in the white paper:
‘Summary of industry cooperative
Figure 1. Micron sizes of familiar particles. The greatest dangers to high‑pressure
common rail (HPCR) fuel injection systems comes from particles 2
–
3 μm in size.
Figure 2. This graph depicts the average number of particles counted downstream
from each filter, per minute of each test.
52
|
World Coal
|
June 2015
