Efficient Plant February 2020 - 16

feature | lubrication strategies
This table compares the
most common oil-analysis lab tests with readily
available sensors that can
emulate the changes in
various oil physical and
chemical properties.

Commonly available sensor-based oil-analysis testing
Fluid properties

Contamination

Wear-debris analysis

Elemental analysis

Particle count

FTIR

Moisture

Elemental analysis

AN (acid number)

FTIR

WPC/Ferrous density

Viscosity/temperature

Viscosity

DR Ferrography

BN (base number)

Elemental analysis

Morphological particle sensor

Proactive monitoring
Oil-condition sensors

Condition-monitoring and
wear-debris sensors

ed in hydraulic-pump cavitation or other issues. The
next routinely scheduled oil sample was 25 days out,
meaning that this problem could have continued for
another three or four weeks without being identified.
In addition to particle-count sensors and
smart-desiccant breathers that measure the degree
and direction of breather saturation in real time, the
number and type of sensors available for monitoring
lubricants has grown dramatically in the past five
years. Today almost every physical or chemical property of oil that has traditionally been monitored using
lab-based oil analysis can be monitored in real time
using a sensor. The table above compares the most
common oil-analysis lab tests with readily available
sensors that can emulate the changes in various oil
physical and chemical properties. As the table indicates, the only oil-analysis parameter that cannot be
easily replicated in real time is elemental analysis that
relies on atomic emission or absorption to report the
concentration of wear metals, certain contaminants,
and inorganic additives.
With many sensors to choose from, the most obvious question is: Which are most effective? The key to
answering that question is to thoroughly understand
failure modes and how quickly certain oil properties
change with time. While some homogeneous properties of oil, such as viscosity, change much slower than
others. Information that can change daily, hourly,
every minute, or even every second, is far more valuable to monitor in real time. These include particle
and water contamination, wear debris content, and,

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Predictive monitoring
Moisture sensors

Oil-analysis lab

to some extent, overall oil quality. Comparing the
constantly changing parameters with real-time operational parameters such as load, speed, temperature,
operation cycle, and execution of certain maintenance
procedures can provide unprecedented insight into
how the lubricant is responding to normal and abnormal operating conditions.
Like all sensor-based condition monitoring
technologies, real-time oil analysis is not intended
to replace bottle samples and lab analysis. For the
short to medium term, there will always be a need to
trust the knowledge, skills, accuracy, and precision
offered by a commercial oil-analysis lab. In the future,
oil-analysis labs will become more like "forensic labs,"
using their expertise to determine the underlying
root causes and reasons for problem conditions first
identified using sensors such as lubricant degradation
or increased wear trends. Sensors will become the
de-facto warning to check oil or machine condition.
Combined with operational data, we are entering a
new era in which integrated condition monitoring
and operational context will give us unprecedented
insight into how our equipment functions. Combined
with "big data" machine learning capabilities, these
are exciting times for oil analysis. EP
Mark Barnes, CMRP, is Senior Vice President at DesCase Corp., Goodlettsville, TN (descase.com). He has
21 years of experience in lubrication management, oil
analysis, and contamination control and has published
more than 150 technical articles and white papers.

FEBRUARY 2020

1/28/20 5:48 PM

http://www.descase.com http://www.EFFICIENTPLANTMAG.COM

Efficient Plant February 2020

Table of Contents for the Digital Edition of Efficient Plant February 2020