techniques, and intervals for all Navy equipment.
concentration of wear metals in the lubricating
The CFA also establishes and maintains sampling
fluid. This analysis is accomplished by subjecting
the sample of fluid to a high-voltage spark. This
information for the maintenance requirements
energizes the atomic structure of the metal
cards (MRCs). It also maintains maintenance
instruction manuals (MIMs) for the respective
elements and causes the emission of light. The
equipment or weapon systems.
emitted light is then focused into the optical path
Spectrometric oil analysis is a diagnostic
of the spectrometer and separated by wavelength.
It is then converted to electrical energy, and
maintenance tool used to determine the type and
measured. The emitted light for any element is
amount of wear metals in lubricating fluid
proportional to the concentration of wear metal
samples. Engines, gearboxes, and hydraulic
suspended in the lubricating fluid.
systems are the types of equipment most fre-
2. Atomic Absorption--The atomic absorp-
quently monitored. The presence of unusual
tion spectrometer is an optical instrument. It is
concentrations of an element in the fluid sample
also used in determining the concentration of
indicates some abnormal wear of the equipment.
wear metals in the lubricating fluid. The fluid
Once the abnormal wear is verified and pin-
sample is drawn into a flame and vaporized. The
pointed, the equipment may be repaired or
atomic structure of the elements present become
removed from service. This is done before a major
sufficiently energized by the high temperature of
failure of the fluid-covered part occurs. This
the flame to absorb light energy. Light energy
philosophy enhances personnel safety and
having the same characteristic wavelength as the
material readiness at a minimum cost, and serves
as a decisive tool in preventive maintenance
element being analyzed is radiated through the
flame. The resultant light is converted to electrical
action. Thus, worn parts may be replaced prior
energy and measured electronically. The amount
to a catastrophic failure.
of light energy absorbed by the elements in the
flame is proportional to the concentration of wear
Wear Metals
metals.
Wear metals are generated by the motion
NOTE: The spectrometric fluid analysis
between metallic parts, even though lubricated.
method is effective only for those failures
For normally operating equipment, the wear metal
that are characterized by an abnormal
is produced at a constant rate. This rate is similar
for all normally operating equipment of the same
increase in the wear metal content of the
model. Any condition that changes the normal
lubricating fluid. This is particularly true
of failures that proceed at a rate slow
relationship will accelerate the rate of wear and
enough to permit corrective action. This
increase the quantity of wear metal particles
is done after receipt of notice from the
produced. If the condition is not corrected, the
laboratory.
deterioration will increase and cause secondary
damage to other parts of the assembly. This can
The value of a spectrometric analysis is based
result in the final failure of the entire assembly
on the assumption that the oil sample is represent-
and loss of the equipment. New or newly
ative of the system from which it is taken.
overhauled assemblies tend to produce wear metal
in high concentrations during the initial break-in
Occasionally, samples from one part may be
period.
substituted for another, resulting in a false
appearance of a developing wear condition. A
sudden increase of wear metal in one part and a
Identification of Wear Metals
decrease in another should be considered as a
problem related to sample error; for example,
The wear metals produced in fluid lubricated
misidentifying a sample as an engine sample when
mechanical assemblies can be separately mea-
it was actually a transmission sample.
sured. This is done in extremely low concentra-
tions, by spectrometric analysis of fluid samples
Oil Sampling Techniques
taken from the assembly. Two methods of
spectrometric oil analysis are currently used to
Sampling' intervals should be as close as
measure the quantity of various metals.
possible to specified times without interfering with
scheduled operations. Generally, the sampling
1. Atomic Emission--The emission spectrom-
intervals should not vary more than 10 percent
eter is an optical instrument used to determine the
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