4 Maintenance
procedures |
Specifications for
all measurements taken on a component, such as oil
pressure and compression readings, should be available to
the maintenance staff as it is necessary to know whether
or not the result is acceptable. It is possible to trend
the readings within the specifications to obtain even
more information on the health of the machine.
5 Regular
sampling |
Intervals between
samples should not be too long. The recommended periods
should be in the region of 250 hours (10,000 km) for
engines, and 500 (20,000 km) for other components. If
samples are not taken regularly, a wear problem could
degenerate from borderline to critical, and failure could
occur with no apparent warning.
6 Sample
quality |
Oil analysis depends
entirely on the integrity of the sample. If the sample
has been taken incorrectly and is contaminated or taken
from an incorrect sampling point, the results will not be
representative of the main body of oil and erroneous
conclusions will be drawn.
The sample must be taken
hot and well mixed. Oil samples can be taken from the
drain plug as the oil is drained, or a thief gun can be
utilized. Another method is to use the sampling valve
which should be located at a well selected point on the
component, i.e. not after a filter or on a dead leg.
Samples taken at failure
cannot be taken with the machine running and this could
lead to an unrepresentative sample being submitted.
7 Sample
information |
To obtain the best
results from the program, information supplied with the
sample must be accurate and complete. If all the relevant
facts are not available to the diagnosticians when they
interpret sample results, an incorrect diagnosis could be
made. Critical information includes:
Correct
identification
The fleet or
serial number and the component need to be correctly
identified. If the clerk transposes the fleet number or
writes left instead of right, the results will be
recorded against the incorrect piece of equipment.
In the event of the
results indicating a problem, the wrong component will be
stripped and will probably show no fault. This could make
oil analysis appear unreliable.
Service meter
reading
This is
important information as a new component will wear
differently from and old one. If the diagnostician does
not know the age of a piece of equipment, he is unable to
give an accurate assessment of the results.
Length of time oil
has been in use
This is
necessary as the levels of wear metals increase with time
and what is normal for 500 hours could be critical for
100 hours.
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