Lubricating Oil Effectiveness
The primary function of liquid lubricants is
to minimize or eliminate friction, wear, and surface damage
to machine elements such as bearings and gears. Secondary
functions include corrosion resistance, heat reduction, and
prevention of dirt and wear debris damage. The effectiveness
of these functions are significantly reduced when the oil
becomes contaminated or oxidizes. It is estimated that water
contaminated oil can shorten bearing life by as much as 85
percent!
Oil Contamination
The two major types of oil contamination are water and particulate
(solids).
Causes:
- Water contamination is common
in equipment where high humidity levels exist. Rain, steam
quenching, and equipment cleaning are also sources of
water leading to equipment lubrication contamination.
Water content in oil is visible to the naked eye above
400 ppm concentration. Water contamination of oil in concentration
levels as low as 200 ppm can be damaging. Poor bulk lubricant
storage and transfer methods often lead to high levels
of both water and particulate contamination.
- Particulate contamination is common where high levels of airborne particles of solids
such as paper pulp, dust, metals, and chemical residue
exist. The naked eye can see only particles 80 microns
in size or greater. Major bearing manufacturers recommend
micron size of no greater than 13 microns be allowed in
equipment lubrication. Poor storage and transfer methods
are major contributors to oil contamination. Use of Trico
air dryers can reduce relative humidity levels in equipment
to reduce and often eliminate water contamination of oil.
Prevention: Oil lubricated equipment
will draw in surrounding air during temperature changes, resulting
in pressure increase and decrease cycles, allowing humidity
and airborne particulate to enter the equipment lubrication.
Sealing the equipment with Trico closed system lubricators,
pressure-maintaining expansion chambers, and proper seals
significantly reduce, and often eliminate lubricant contamination.
Oxidation
The rate of chemical oxidation of oil doubles with each 18
degree F rise in temperature. This significantly shortens
the effective life of the equipment lubrication.
Causes: Oxidation can be caused
by both excessive lubrication (high levels in wet sump applications)
and lubricant starvation (low levels). Improper oil viscosity
and selection also often lead to higher operating temperatures
and increased oxidation rates.
Prevention: Proper setting of
Trico's Opto-Matic® constant level oilers ensure optimum
oil levels, that prevent oxidation caused by excessive or
inadequate lubrication. Use only equipment manufacturer recommended
oil type and viscosity.