technical
APRIL 2016 http://www.yachtingmonthly.com 85particles down to 1.5 microns
in diameter.
The ISO test procedure for
filters is a multi-pass test, in
which the fuel is recirculated
through the filter over and over.
This is more appropriate for
hydraulic systems than it is for
diesel fuel supplies and engines.
It uses hydraulic oil, which is
far more viscous than diesel
fuel. Also, the test does not
account for vibration and sudden
changes in engine speed, both of
which have been found to cause
rapid and considerable increases
in the number of contaminants
of a given size passing through
a fuel filter.Water in the fuel
Problems are compounded
by the surfactancy of the
additives to ULSD, and by
biodiesel’s natural surfactancy.
One of the main purposes of
most primary fuel filters is to
remove any water from the
fuel supply. Unfortunately, the
increased surfactancy of ULSD
and biodiesel reduces water
droplets to a size at which a
high percentage of the droplets
can pass through conventional
separation media.
The bottom line: diesel fuel
that meets current supply chain
and WWFC standards, fedthrough filters that
pass the relevant
tests, can threaten
the health of modern
fuel injection
systems. To meet fuel
cleanliness targets
with HPCR engines,
multiple-stage filtration
at the two-micron level may
be needed.Paranoia
recommended
The situation is likely to improve
over time. Upcoming changes in
emissions and engine efficiency
standards, in particular the
forthcoming Euro 7 requirements
for automotive diesels, will lead
diesel engine manufacturers
to demand higher-efficiency
filters that will then find their
way into marine and aftermarket
filtration systems.
Nevertheless, it will take
some time for the effects of
changing emissions and fuel
filtration standards, and engine
manufacturers’ requirements,
to have a practical impact in the
marine filter marketplace. In the
interval, anyone with a high-
pressure injection system should
be somewhat paranoid about the
quality of fuel supplies and the
level of filtration being provided
for the engine. WNot all new diesel engines are HPCR. These Kubota engine blocks,
awaiting marinisation by Beta Marine, still use conventional technologyPHOTO: GRAHAM SNOOK/YMPHOTO RiGHT & BELOW: GRAHAM SNOOK/YM
PHOTO: NiGEL CALdER
Nigel accessing his fuel tank to pump out contaminated fuel
Even minor contamination like this could wreak havoc
if it made it to the high pressure side of the engine