Hazy or cloudy oil may be the result of water
contamination. The crackle test can be used to
verify the presence of water in oil, but does not
give any quantitative results. The crackle test
can be conducted by making a small cup from
aluminum foil, adding a few drops of the oil, and
heating rapidly with a small flame. The test can
also be conducted by Immersing a hot soldering
iron in a sample of the oil. In either method, a
audible crackling sound will be heard if water is
present. Eye protection should be worn during
the test as oil may splatter while being heated.
contamination. The crackle test can be used to
verify the presence of water in oil, but does not
give any quantitative results. The crackle test
can be conducted by making a small cup from
aluminum foil, adding a few drops of the oil, and
heating rapidly with a small flame. The test can
also be conducted by Immersing a hot soldering
iron in a sample of the oil. In either method, a
audible crackling sound will be heard if water is
present. Eye protection should be worn during
the test as oil may splatter while being heated.
If water is found during the visual inspection, the
oil should be purified and a sample of the puri-
fied oil sent to a laboratory for analysis. If
sediment is found, the oil should be purified and
samples of the unpurified oil and the purified oil
should be sent in for analysis. In this way the
sediment of the unpurlfied oil can be analyzed to
determine its source.
oil should be purified and a sample of the puri-
fied oil sent to a laboratory for analysis. If
sediment is found, the oil should be purified and
samples of the unpurified oil and the purified oil
should be sent in for analysis. In this way the
sediment of the unpurlfied oil can be analyzed to
determine its source.
The oil's neutralization number can also be de-
termined in the field. With the exception of
some motor oils, which may be alkali, most
lubricating oils are essentially neutral. If an oil is
found to be acidic, it is likely the result of
oxidation of the oil due to extended service or
abnormal operating conditions. The neutraliza-
tion number of new oil is usually less that 0.08.
The maximum allowable number depends on
the type of oil and its service, and should be
obtained from the oil manufacturer. The maxi-
mum value, is usually less than 0.5. Of greatest
concern in this test is the rate of increase, not
necessarily the neutralization number itself. A
sudden increase in the neutralization number
may indicate that the some operational problem
exists or that the oil has simply reached the end
of its useful life. In either case, some action is
required before further deterioration and equip-
ment damage occurs. If a large increase in the
neutralization number is found or if the number
exceeds the maximum allowable, the oil's man-
ufacturer should be contacted to determine
what, if anything, can be done to reclaim the oil.
termined in the field. With the exception of
some motor oils, which may be alkali, most
lubricating oils are essentially neutral. If an oil is
found to be acidic, it is likely the result of
oxidation of the oil due to extended service or
abnormal operating conditions. The neutraliza-
tion number of new oil is usually less that 0.08.
The maximum allowable number depends on
the type of oil and its service, and should be
obtained from the oil manufacturer. The maxi-
mum value, is usually less than 0.5. Of greatest
concern in this test is the rate of increase, not
necessarily the neutralization number itself. A
sudden increase in the neutralization number
may indicate that the some operational problem
exists or that the oil has simply reached the end
of its useful life. In either case, some action is
required before further deterioration and equip-
ment damage occurs. If a large increase in the
neutralization number is found or if the number
exceeds the maximum allowable, the oil's man-
ufacturer should be contacted to determine
what, if anything, can be done to reclaim the oil.
Laboratory Tests. Laboratory tests should in-
clude tests for viscosity, neutralization number,
clude tests for viscosity, neutralization number,
water contamination, and the identity of wear
metal and other contaminants and can usually
be accomplished by local laboratories or by the
Applied Science Branch, D-3740, In
Reclamation's Denver Office. If at all possible,
the oil's manufacturer should perform tests pe-
riodically. Since the composition and additive
content of oils is usually considered proprietary
information, only the manufacturer can accu-
rately determine the extent of additive depletion.
The manufacturer should also be contacted
anytime the tests indicate there is some ques-
tion about the continued serviceability of an oil.
metal and other contaminants and can usually
be accomplished by local laboratories or by the
Applied Science Branch, D-3740, In
Reclamation's Denver Office. If at all possible,
the oil's manufacturer should perform tests pe-
riodically. Since the composition and additive
content of oils is usually considered proprietary
information, only the manufacturer can accu-
rately determine the extent of additive depletion.
The manufacturer should also be contacted
anytime the tests indicate there is some ques-
tion about the continued serviceability of an oil.
Test Schedule. Samples should be drawn from
all guide bearings and governors annually and
submitted for laboratory analysis. In addition to
the annual tests, samples should be visually
inspected at frequent Intervals. In most cases,
annual laboratory testing is sufficient, but more
frequent testing may be warranted if a visual
inspection of the oil indicates the presence of
water or sediment, or if previous laboratory tests
had indicated a sudden increase in contami-
nants or oxidation products.
all guide bearings and governors annually and
submitted for laboratory analysis. In addition to
the annual tests, samples should be visually
inspected at frequent Intervals. In most cases,
annual laboratory testing is sufficient, but more
frequent testing may be warranted if a visual
inspection of the oil indicates the presence of
water or sediment, or if previous laboratory tests
had indicated a sudden increase in contami-
nants or oxidation products.
4.4 Oil Purification and Filtration
In order for a lubricating oil to perform properly
it must be kept free of contaminants. In most
hydraulic systems, an in-line filter is employed
to continually filter the oil any time the system is
in operation, but in most lubricating systems, the
oil is filtered or purified periodically. The
frequency of purification should be based on the
results of the oil testing program.
it must be kept free of contaminants. In most
hydraulic systems, an in-line filter is employed
to continually filter the oil any time the system is
in operation, but in most lubricating systems, the
oil is filtered or purified periodically. The
frequency of purification should be based on the
results of the oil testing program.
Water is the most common contaminant found
in hydroelectric plants and its presence in oil
may promote oxidation, corrosion, sludge for-
mation, foaming, additive depletion, and
generally reduce a lubricant's effectiveness.
Solid contaminants such as dirt or dust and wear
particles may also be present. These solid
particles may increase wear, and promote
sludge formation, foaming, and restrict oil flow
within the system. To remove contaminants
in hydroelectric plants and its presence in oil
may promote oxidation, corrosion, sludge for-
mation, foaming, additive depletion, and
generally reduce a lubricant's effectiveness.
Solid contaminants such as dirt or dust and wear
particles may also be present. These solid
particles may increase wear, and promote
sludge formation, foaming, and restrict oil flow
within the system. To remove contaminants
11 (FIST 2-4 11/90)