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bet you can't find it anywhere. Why is
that? ISO 16889 (industrial oil filters)
and ISO 4548 (diesel engine oil filters)
both include dirt-holding capacity as a
standard reported value.
In the example of the three candidate
filters, we'll estimate that 200 kilograms
of dirt must be removed over a year's
time for the entire fleet. In the table to
the left, the differences in filter price are
shown. e three filters were tested inde-
pendently on a multipass test stand, and
the dirt-holding capacities were found to
be 250, 160 and 125 grams, respectively.
Based on the 200 kgs of total dirt, the
number of filters required is 800 for the
premium high-priced filter and 1,600 for
the economy brand.
Also included in the financial anal-
ysis is the labor cost of replacing a filter.
I used $25 per filter, but there are many
other hidden costs I did not include.
ese include purchasing, stockroom
and handling, planning and scheduling,
used filter disposal, waste oil handling
and disposal (oil from inside the filter),
record keeping, etc.
When the price per filter (including
labor) and the dirt-holding capacity are
compared together, the economical best
choice is the premium, long-life filter at
a savings of roughly $72,000 per year.
Please note that my data is hypothet-
ical. Don't assume the premium filter
to always be the long-life filter. Do the
testing and get real data. e cost of
testing these three filters would be less
than $4,000 — a small fraction of the
potential savings.
As mentioned, testing reveals other
critical performance differences between
filters as well. e three most important
are particle size retention (how clean
will the filter get your oil), flow resis-
tance (affects energy consumption)
and fabrication integrity (likelihood
of random manufacturing defects). A
larger number of filters will be needed
to get statistically meaningful data for
fabrication integrity. ese other perfor-
mance factors influence the service life
of machine components (bearings,
pumps, gears, etc.), labor and material
cost of repairs, downtime costs, energy
consumption costs and much more.
Where to Start
If I had a fleet of machines and a
large annual filter consumption bill, I
would compile a list of filters consumed
in high volume and those that indi-
vidually cost the most. is is your
Cost Factor List. Next, I would look at
mission-critical machines and the filters
used there. For such machines, there is
a need for far greater performance to
ensure reliable and consistent contam-
ination control. is is your Criticality
Factor List. Many filters will appear on
both lists.
By ranking the filters from two lists,
you focus testing where the economic
opportunity is the greatest. For more
information on how to get your filter
tested, contact Noria Corporation. ML
About the Author
Jim Fitch has a wealth of "in the
trenches" experience in lubrication,
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 books. He serves as
a U.S. delegate to the ISO tribology and
oil analysis working group. Since 2000,
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.
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