increase in viscosity may so alter lubricating
properties that the oil is no longer suitable for its
intended application.
properties that the oil is no longer suitable for its
intended application.
If, on the other hand, the flash or fire points drop
in service, contamination is to be suspected.
This may happen to motor oils that become
diluted with unburned fuel. Gasoline or heavier
in service, contamination is to be suspected.
This may happen to motor oils that become
diluted with unburned fuel. Gasoline or heavier
fuels in the crankcase reduce the viscosity of
the oil, and bearings and other moving parts
may be endangered by excessive thinning of the
lubricant. These fuels, being more volatile than
the oil, lower the flash and fire points of the
mixture. So the flash- or fire-point test on used
oils constitutes a relatively simple method for
indicating the presence of dilution.
the oil, and bearings and other moving parts
may be endangered by excessive thinning of the
lubricant. These fuels, being more volatile than
the oil, lower the flash and fire points of the
mixture. So the flash- or fire-point test on used
oils constitutes a relatively simple method for
indicating the presence of dilution.
FOAMING CHARACTERISTICS OF LUBRICATING OILS
ASTM D 892
Foaming in an industrial oil system is a serious
service condition that may interfere with satis-
factory system performance and even lead to
mechanical damage.
service condition that may interfere with satis-
factory system performance and even lead to
mechanical damage.
While straight mineral oils are not particularly
prone to foaming, the presence of additives and
the effects of compounding change the surface
properties of the oils and increase their suscep-
tibility to foaming when conditions are such as to
mix air with the oils. Special additives impart
foam resistance to the oils and enhance their
ability to release trapped air quickly under con-
ditions that would normally cause foaming
prone to foaming, the presence of additives and
the effects of compounding change the surface
properties of the oils and increase their suscep-
tibility to foaming when conditions are such as to
mix air with the oils. Special additives impart
foam resistance to the oils and enhance their
ability to release trapped air quickly under con-
ditions that would normally cause foaming
Apparatus: The foaming test apparatus consists
of special 1000-mi graduated cylinders, air inlet
tubes, and fused alumina gas diffuser stones.
Also two constant-temperature water baths (one
at 75° F and one at 200° F), a compressed air
supply, drying tower 300 mm in height,
flowmeter, wet-test meter or other gas-volume
measuring device, stopwatch or timer, and
thermometers meeting ASTM specifications.
of special 1000-mi graduated cylinders, air inlet
tubes, and fused alumina gas diffuser stones.
Also two constant-temperature water baths (one
at 75° F and one at 200° F), a compressed air
supply, drying tower 300 mm in height,
flowmeter, wet-test meter or other gas-volume
measuring device, stopwatch or timer, and
thermometers meeting ASTM specifications.
Preparation of Apparatus: Thorough cleansing
with the prescribed solvents and drying of the
test cylinders and gas diffuser stones are
required for proper preparation of the apparatus.
with the prescribed solvents and drying of the
test cylinders and gas diffuser stones are
required for proper preparation of the apparatus.
Procedure
a) Pour a 190-ml sample of the oil to be tested,
which has been previously heated to 120° F and
cooled to 75° F, into a graduated cylinder, im-
mersed at least to the 900-mi mark in the 75°F
constant-temperature bath. Immerse a diffuser
stone in the sample, adjust air flow to 95 mi per
minute and, then, connect the air-inlet tube to
the stone and, force air through the stone for 5
minutes. Then disconnect the tube and imme-
diately record the volume of foam. Allow the
sample to stand for 10 minutes and again record
the foam volume.
a) Pour a 190-ml sample of the oil to be tested,
which has been previously heated to 120° F and
cooled to 75° F, into a graduated cylinder, im-
mersed at least to the 900-mi mark in the 75°F
constant-temperature bath. Immerse a diffuser
stone in the sample, adjust air flow to 95 mi per
minute and, then, connect the air-inlet tube to
the stone and, force air through the stone for 5
minutes. Then disconnect the tube and imme-
diately record the volume of foam. Allow the
sample to stand for 10 minutes and again record
the foam volume.
b) Pour a 180-ml sample of the oil being tested
into a graduated cylinder, immersed at least to
the 900-mi mark in the 200° F bath. When the
sample reaches the bath temperature, insert a
clean diffuser stone and proceed as with the
previous sample, recording foam volume at the
end of the blowing and settling period.
into a graduated cylinder, immersed at least to
the 900-mi mark in the 200° F bath. When the
sample reaches the bath temperature, insert a
clean diffuser stone and proceed as with the
previous sample, recording foam volume at the
end of the blowing and settling period.
c) Collapse any foam remaining after the 200° F
test by stirring. Remove the sample from the
bath and let cool to a temperature below 110° F.
Then place the cylinder in the 75° F bath. Insert
a diffuser stone and repeat the above
procedure.
test by stirring. Remove the sample from the
bath and let cool to a temperature below 110° F.
Then place the cylinder in the 75° F bath. Insert
a diffuser stone and repeat the above
procedure.
Reporting the Results: The test results are
reported as volume of foam, in mi, at tile end of
the 5-minute blowing period, and at the end of
the 10-minute settling period, for the three dif-
reported as volume of foam, in mi, at tile end of
the 5-minute blowing period, and at the end of
the 10-minute settling period, for the three dif-
A-5 (FIST 2-4 11/90)