diesel injector hard particle wear
testing conducted at Southwest
Research Institute’. This two-part study
sought to determine:
n
n
Which size particles, measured in
microns (μm), were most likely
to cause injector wear and other
damage to HPCR systems.
n
n
The filtration efficiency needed to
protect HPCR systems from the
most threatening contamination.
The 2011 research phase concluded:
n
n
Particulates in the range of
2 – 3 μm produced mechanical
damage in HPCR systems.
n
n
A different type of damage and
wear occurred in the HPCR
systems compared to the
lower‑pressure systems of the past
(abrasive wear). First, initial impact
wear occured on the seal face. As
those indentations continued to
accumulate, severe erosive wear
occured due to the high pressure
leakage of fuel that contains
particulate passing across the
sealing face when closed.
n
n
Filter integrity and consistent,
high-efficiency performance is
essential to protect modern HPCR
injection systems.
n
n
This test concluded that not all
filtration performs equally. Some
are effective against dangerous
contaminants and some are not.
These conclusions should be of
concern for anyone who operates
modern equipment with HPCR
engines, because ISO 4406 codes – the
current standard for measuring fuel
cleanliness – only take into account
particles of 4 μm and larger. This
makes it extremely important to pay
special attention to how diesel is
filtered, because, as Figure 2 shows,
most filtration systems are designed to
meet ISO 4406 cleanliness codes,
without focusing on or measuring the
efficiency of removing the large
number of 2 – 3 μm particles. But
Figure 2 also shows that with the
correct filtration, an operator can
drastically reduce the number of those
particles.
Laboratory results prove
bigger real-world dangers
While the 2011 SwRI research was
conclusive, it was also conducted in a
controlled environment. As anyone
who has ever been involved with a
mining operation knows, the typical
real-world working environment is
anything but controlled. Coal dust, for
example, can be anywhere from
sub-micron to 100 μm in size. And it is
just one of the many potential jobsite
contaminants that can change diesel
fuel from the substance that keeps
equipment running into the very thing
that brings an entire operation to a
halt.
Contamination comes in
many forms, from many
places
Fuel contamination can be separated
into two broad categories: inorganic
and organic. Inorganic contaminant is
typically hard particulate (dirt) picked
up throughout distribution. From the
refinery, fuel is typically clean to
acceptable standards, but as it gets
transported throughout distribution
(which can include pipelines,
terminals and delivery trucks) it gets
more and more contaminated. Once
onsite, as it is stored in bulk tanks and
moved for distribution and use, it
picks up contamination from
infrastructure and ambient
conditions, such as through vent
pipes with inadequate filtration.
Organic contaminant represents
anything carbon-based, typically
hydrocarbons with various chemicals
attached. These organic contaminants
can also come from a variety of
sources at or downstream of the
refinery: lubricity improvers, cold
flow improvers, biodiesel and
corrosion inhibitors, etc. (While coal
dust is in fact organic, it does not fall
under the category of an organic
contaminant because it lacks the
hydrogen component, as well as the
functional additive chain).
“It is very important for fuel
additives to be dosed at the right
levels and under the right conditions
to ensure the best overall fuel
stability, otherwise these additives
can become insoluble and therefore
unfilterable,” Doyle explained.
Generally speaking, hard
particulate (inorganic contaminant,
such as was used in the SwRI study or
particles like coal dust) will cause
permanent damage to the injector
system, while softer particulate
(organic contaminant, such as
glycerin or various precipitates
caused by adverse fuel chemistry
reactions) will cause fouling, i.e.
deposits building up on the injectors.
In both cases the engine does not run
as-designed and can result in a
Figure 3. Protecting investments with Donaldson Clean Solutions 4 Filter Manifold
(with a maximum flow range of 250 gal./min. [946 l/min.]) decreases fuelling time and
ultimately increases flow capacity from tank and equipment.
June 2015
|
World Coal
|
53
