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SVOC Alternatives
Fully purging a system of oil can
be a difficult challenge. is is espe-
cially true with completely flooded
lines and system components. e
procedure may require partitioning
the system, followed by breaking
into lines in low zones to drain
used oil and aided by air vents in
higher zones. ere are a couple of
alternatives to consider based on the
machine, the operating conditions
and the need for an FVOC. ese
include the following (see also the
table in Figure 2):
Bleed-and-Feed
is type of oil change normally
can be performed on the run for
stationary equipment without the
loss of machine runtime. e process
involves the progressive draining
of tank oil and the addition of an
equal amount of new oil, all while
the oil remains circulating. For
heavily degraded lube oil, it may
take the equivalent of three or four
oil changes (in new oil volume) to
achieve the target level of oil quality
and performance.
Double Oil Change
is will require a machine stop-
page. e tank is drained and refilled
in the same manner as with a normal
SVOC. e oil is then brought back
to operating temperature while
circulating. Afterward, the oil tank
is drained and refilled again.
SVOC Followed by a Line Purge
After the tank has been drained
and refilled with new oil, the auxil-
iary pump is started and the new
oil is pushed into the system. e
old oil is not returned to the tank
but rather diverted to waste until
most of the old line oil has been
discharged. e tank is then refilled
to the correct level, and the return
line is reconnected to the tank.
Alternate procedures can achieve
similar results depending on the
machine/system involved.
Role of Oil Analysis
Oil ana lysis and Inspection
2.0 ca n substa ntia lly improve
the outcome of SVOCs and miti-
gate the risks. is is largely the
practice of carefully monitoring
the aging health of the used oil
and recognizing the sudden and
escalating presence of a problem.
Issues might include premature oil
oxidation, the need for dehydration
or portable filtration, rising varnish
potential, the need for additive
reconstruction and abnormal ghost
rider concentration.
For large and critical systems,
the timing of the oil change is key.
e best way to ensure good timing
is to allow the oil to talk to you
through effective oil analysis and
inspection. When done correctly,
these methods will enable you to
achieve optimum results.
ML
About the Author
Jim Fitch has a wealth of "in
the trenches" experience in lubri-
cation, oil analysis, tribology and
machinery failure investigations.
Over the past two decades, he has
presented hundreds of courses on
these subjects. Jim has also published
more than 200 technical articles,
papers and publications. He serves as
a U.S. delegate to the ISO tribology
and oil analysis working group. Since
2002, he has been the director and
a board member of the International
Council for Machinery Lubrication.
He is the CEO and a co-founder of
Noria Corporation. Contact Jim at
jfitch@noria.com.