Though it is sometimes overlooked, equipment owners
should always specify the grease to be used by the
companies that rebuild motors (and other equipment
with greased bearings) for them. Otherwise, the
grease they use may be incompatible with grease
the owner will use to replenish the bearing lubricant.
It would be time well spent to visit a frequently
used shop, and ask someone on the shop floor to
show you how he or she knows what grease to add
to your equipment bearings. (Submitted by Van Richard,
Sr. Reliability Engineer, Georgia Gulf. Thanks Van!)
From the "How to Select a
Motor Oil for Your Car or Truck"
Sooner or later, wear from abrasive particles and
deposits from carbon and oxide insolubles will interfere
with efficient combustion in an engine. Valve train
wear (cams, valve guides, etc.) can impact timing
and valve movement. Wear of rings, pistons and cylinder
walls influences volumetric compression efficiency
and combustion blow-by resulting in power loss.
Particle-induced wear is greatest when the particle
sizes are in the same range as the oil film thickness.
For diesel and gasoline engines, there is a surprising
number of laboratory and field studies that report
the need to control particles below 10 microns.
One such study by General Motors concluded that,
"controlling particles in the 3 micron to 10
micron range had the greatest impact on wear rates
and that engine wear rates correlated directly to
the dust concentration levels in the sump."
| Q
& A: Improving Oil Analysis Results |
"We have an oil sampling program
at our mill on many of our critical systems. We have
installed sampling ports on our hydraulic and oil
circulation systems but rarely see an advance warning
of equipment problems. Consequently, we have unexpected
failures on sampled systems. What can we do to improve
our results?"
There are many factors that can influence the effectiveness
of an oil analysis program, including test slate selection,
alarm levels, laboratory quality, sample frequency,
sample location and equipment operational factors
to name a few. Two common problems that programs encounter
are poor test selection and poorly selected sample
port locations.
While both of these can confuse the
outcome and minimize the effectiveness of analysis,
a properly selected sample location is vital for trending
changing equipment condition. It is possible to assess
lubricant and contamination conditions with samples
taken from many locations in most reservoirs. However,
sampling for evidence of mechanical problems requires
a sample to be collected from a location that contains
the highest concentration of 'evidence' of a problem.
The evidence is of course the wear metals.
Often samples are collected from a
pressure line after a filter, or from a drain line
toward the bottom of a reservoir. This is generally
because these locations enable low cost sample port
installation, easy access and low cost sample collection.
However, these common locations are far from ideal
because the 'evidence' may be filtered or settled
out of the lubricant, leaving the program with little
more than fluid properties information. Sample ports
must be configured to enable collection of lubricant
in close proximity to the mechanical components in
question.
We have heard the axiom about factors
influencing real estate transactions: The top three
factors in maximizing real estate value are location,
location and location.
The same concept applies to oil analysis-based
equipment condition monitoring programs.
Mike
Johnson, Sr. Technical Consultant, Noria Corporation
To reward the lubrication and reliability
community for its participation in the Noria Message
Boards, we've started the Post
of the Week award. Every week, we award one lucky
member $50 (USD).
"The oil could be anywhere between
an ISO 22 and an ISO 68 but it depends on the design
and specifics of the application. I am going to assume
that you are considering an oil cooler to minimize
the circulating oil's temperature and hence give a
similar viscosity across the changing temperature
variations. One thing to remember is that the flow
was originally determined by the oils ability to adhere
to the ring and this was in part a function of the
tackiness or adhesion or surface plating characteristics
of the oil. These functions are partially independent
of ISO viscosity. Also the oil rings supplied the
minimum amount of oil required. As long as the oil
doesn't cause an imbalance or an oil whirl or oil
whip situation you can't put too much oil into the
bearing by simple splash method. So the more you put
in the easier it would be to remove the heat, etc."
