|
Unusual Particle Counts Confusing
Cyril Ontai, Predictive Maintenance Specialist,
Hawaiian Electric Company
Particle counts can increase for a number of reasons. Increase
in loading and shock load, change in equipment usage patterns
and/or duty cycle, defective parts, misalignment and unbalance,
corrosion, degraded lubricant including additives, dirt or abrasive
ingress, and the ingress of other contaminants (Noria, 2004, p.
248).
There are many actions that can be taken in order to locate the
root cause of this problem. Analyzing the oil through other tests
is essential in determining the total composition of the particles
in the oil. Collaborating with equipment personnel to determine
history is also vital. And confirming equipment health with other
technologies quickens the troubleshooting process.
First of all, deeper analysis of the oil particles is vital to
determining the root cause. Particle counting, while good at measuring
the size and quantity of particles in a lubricant, do not determine
what type of debris is in the sample (Insight, 2000). Spectrometric
analysis, ferrous density analysis, and analytical ferrography
are important in determining the composition of the particles
in the oil. Spectrometric analysis indicates the elements, metallurgy,
and concentration in parts per million of an oil sample. Ferrous
Density Analysis, including direct reading ferrography and ferrous
particle counting, help to determine size, metallurgy, and concentration
of particles. And analytical ferrography, including ferrogram,
filtergram, and microscopic analysis, show the size, texture,
metallurgy, and concentration of the particles (Noria). All can
point closely towards the root cause.
Secondly, collaboration with operation and maintenance personnel
can help determine if this equipment recently operated in unusual
circumstances. Change in equipment usage patterns, duty cycle,
and shock load can increase wear in equipment. Also, an inquiry
on recent equipment breakdowns and/or inspections can help to
determine if there were any recent defective parts.
Also, confirm equipment status with other technologies. Vibration
data can determine whether the equipment is misaligned or unbalanced.
Both situations can lead to wear increase in oil sampling. Infrared
thermography can indicate areas of friction and overloading relative
to similar machines.
Finally, visual inspection of the equipment is another initial
step. Rust on the outside of equipment and piping can communicate
that oxidation is prevalent within the system.
While particle counts alarmed the equipment's situation, more
steps are needed to find the root cause. Closer investigation
of the debris reduces the number of possible root causes. Knowing
the history of the equipment also is essential in the troubleshooting
process. And the use of other technologies confirms equipment
status as well as reduces possible root causes. The combination
of these steps should ensure the closer of this case.
References:
Insight Services. (2000). The New Practical Guide To Oil Analysis.
Insight Services. Cleveland , OH
Noria Corporation. (2004). Oil Analysis Course Manual. Noria
Corporation
See other responses
to this Readers Challenge.
Discuss
this topic on our message boards.
|
