September 2022 - 22

feature | lubrication solutions
ranges in 1 ml of fl uid or oil. Th e ISO " code "
n is 2^n = number of particles of that size
per ml.
Based on OEM recommendations and
accepted industry standards, there are target
ISO cleanliness levels for various industrial
equipment types and the limit is typically
two codes above the target, one code to
account for the test's inherent uncertainty
of +/- one code, and one more because the
alarm should be set at the nearest gradation
from the target. Th ere is also signifi cant
information available regarding the ISO
cleanliness codes and how to set targets.
Dynamic alarm limits, on the other hand,
update with each sample submitted because
they are set by algorithms that account for
the trends established by historical data.
Th ese limits are ideal for measurements that
are not necessarily unique to a lubricant
product or equipment type, or that are
known to change over time but do not necessarily
indicate a potential failure unless
there is a step change. Perhaps the most
useful application of dynamic limits is in
measuring wear metal rates over time.
Th ere are two factors to consider when
using dynamic alarm limits:
S Th ere must be a data history to establish
a trend and an acceptable delta. Static limits
must be used for wear metals until a suffi cient
set of data has been collected-typically three
to fi ve samples. Th e sample must be collected
in a way that maximizes the signal to noise in
the data, i.e., a sample that is representative of
equipment operating conditions).
S Dynamic limits are very sensitive to
change. Communication between end user
and lab is of utmost importance. If oil changes
and other maintenance activities occur
between scheduled samplings, and the lab is
not notifi ed and continues to trend the data, it
is likely that the limits set will not correlate to
the actual component wear rates of that asset.
Th e limits will be set based on measurements
that were acquired under diff erent sets of
Th ere are very diff erent but complementary
sets of knowledge between a commercial
oil lab's analyst team and a maintenance-and-reliability
team. Th e alarm
limits for laboratory tests are set using the
best information the lab has available but,
because so many variables are at play with
industrial equipment, without steady communication
regarding equipment operation
and conditions, even the most meticulously
set alarm limits might fall short of catching
potential failures. Alarm limits don't tell the
whole story. Expertise is required. A strong
working relationship with a trusted lab is a
key component. EP
David M. Gawelek, CLS, is Reliability Concierge
Program Manager at Eurofi ns TestOil,
Strongsville, OH (
The steel industry's top performing calcium
sulfonate grease specially designed for the
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September 2022

Table of Contents for the Digital Edition of September 2022

September 2022 - Cover1
September 2022 - Cover2
September 2022 - 1
September 2022 - 2
September 2022 - 3
September 2022 - 4
September 2022 - 5
September 2022 - 6
September 2022 - 7
September 2022 - 8
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September 2022 - Cover3
September 2022 - Cover4