Excerpt
Reducing Data Noise
"Unfiltered or poorly filtered oil eventually results in
growing concentrations of wear debris. The problem is mutually
compounding in that the dirtier the oil the more contaminated the
oil continues to become from internal wear debris production and
destruction to contaminant exclusion seals. While it is always
good advice to maintain clean lubricants from a proactive
maintenance standpoint (affirmative action), it is equally good
advice for predictive maintenance (early wear detection). A
failure to do so usually leads to the alarm signal effectively
being "lost in the sauce." This concentrated debris results in
a high noise threshold, and when an incipient wear signal occurs
it will write "in the noise" and be lost (signal-to-noise is less
than 1:1). This is a persistent problem with splash-fed gearing,
crankcase lubes, and bath lubricated bearings.
"Conversely, a clean oil provides not only a healthy and
unabrasive lubricating environment but also allows the wear
signal (incipient debris generation) to write above the noise
level (signal-to-noise is greater than 2:1, for example). When
the fluids are maintained clean and if sampling is carried out
in live zones (before filters, on bearing drain lines, and at
turbulent fluid zones) the early detection of wear anomalies is
typically achieved. There is often a need for the routine use
of portable filtration systems or retrofitted side-loop filters.
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