# D445_12 (17a)

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For steam-refined cylinder oils
and black lubricating oils,
proceed to 12.2 of the written
standard, ensuring a thoroughly
representative sample is used.
The kinematic viscosity
of residual fuel oils
and similar waxy
products can be affected
by the previous thermal history,
and the following procedure
described in 12.1.1 to 12.1.8
of the written standard
shall be followed
to minimize this.
In general, the viscometers
used for opaque liquids are
of the reverse flow type listed
in table A1.1 of the written
standard.
Heat the sample in
the original container
at a temperature between 60
degrees Celsius and 65 degrees
Celsius for one hour.
Place the BS/IP/RF/U-Tube
reverse flow,
or Zeitfuchs Cross-arm, or
Lantz-Zeitfuchs type reverse
flow viscometer for the samples
to be tested in the viscometer
bath or baths at the
required test temperature.
If the viscometers are to be
charged prior to insertion
in the viscometer bath, for
example Cannon Fenske Opaque,
see 12.2.1 of the
written standard.
Upon completion of step 12.1.2
of the written standard,
vigorously stir each sample
for approximately 20 seconds
with a glass or steel
rod of sufficient length
to reach the bottom
of the container.
For samples of a very
waxy nature, or oils
of high kinematic
viscosity, it may
be necessary to
increase the heating
temperature above
65 degrees Celsius
to achieve proper mixing.
The sample should be
sufficiently fluid for ease
of stirring and shaking.
Remove the stirring rod and
inspect for sludge or wax
adhering to the rod.
Continue stirring until there
is no sludge or wax adhering
to the rod.
Recap the container tightly and
shake vigorously for one minute
to complete the mixing.
To protect the
integrity of the sample
should a repeat
analysis be required,
pour sufficient sample to fill
two flasks and loosely stopper.
Each flask should
hold sufficient sample
to fill two viscometers in order
to obtain two determinations.
The second flask is required
to carry out a repeat analysis.
If a repeat analysis
is not a consideration,
the next steps can be performed
using the original container,
loosely capped.
Heat the first sample
flask, or sample container,
between 100 degrees
Celsius and 105 degrees
Celsius for 30 minutes.
Remove the first sample flask or
sample container from the heat,
close tightly, and shake
vigorously for 60 seconds.
Two determinations of the
kinematic viscosity of the test
material are required.
For those viscometers that
require a complete cleaning
after each flow
time measurement,
two viscometers must be used.
These two
determinations are used
to calculate one
result. Charge two
viscometers in the
manner dictated
by the design of the instrument.
For example, for the
Lantz-Zeitfuchs Cross-arm,
or the BS/IP/RF/U-Tube reverse
flow viscometers for opaque
liquids, filter the sample
through a 75 UM filter into two
viscometers previously
placed in the bath.
For samples subjected
to heat treatment,
use a pre-heated filter to
prevent the sample coagulating
during the filtration.
Viscometers which are
charged before being inserted
into the bath may need to
be preheated in an oven
prior to charging the sample.
This is to ensure that
the sample will not be
cooled below test temperature.
After 10 minutes,
adjust the volume
of the sample where the
design of the viscometer
requires to coincide
with the filling marks
as in the viscometer
specifications.
See specifications D446.
Allow the charged
viscometers enough time
to reach the test temperature.
See 12.2.1 of the standard.
Where one bath is
used to accommodate
several viscometers.
Never add or withdraw
or clean the viscometer
while any other viscometer is
in use for measuring flow time.
With the sample
flowing freely, measure
in seconds to within
0.1 second the time
required for the
advancing ring of contact
to pass from the first
timing mark to the second.
Record the measurement.
In the case of samples requiring
heat treatment described
in 12.1 through 12.1.8
of the written standard,
complete the
measurements of flow time
within one hour of completing
12.1.8 of the written standard.
Record the measured flow times.
Calculate kinematic
viscosity, v, in millimeters
squared per second from
each measured flow time.
Regard these as two determined
values of kinematic viscosity.
For residual fuel
oils, if the two
determined values of
kinematic viscosity
agree, within the stated
determinability figure,
see 17.1.1 of the
written standard,
use the average of
these determined values
to calculate the
kinematic viscosity
result to be reported.
This constitutes one analysis.
Record the result. If a second
value, repeat, is required,
then repeat the analysis
after a thorough cleaning
and drying of the
viscometers, starting
from sample preparation steps
12.1.6 of the written standard
using the second flask.
If the original container
has been conditioned
using steps 12.1.2 to 12.1.8
of the written standard,
then this is not suitable
for a repeat analysis.
If the calculated kinematic
viscosities do not agree,
repeat the measurements
of flow times
after a thorough cleaning
and drying of the viscometers
and filtering of the sample.
If the material or
temperature or both is not
listed in 17.1.1 of
the written standard,
for temperatures between 15
degrees Celsius and 100 degrees
Celsius, use an estimate of the
determinability 1.0% and 1.5%
for temperatures
outside this range.
It must be realized that these
materials can be non-Newtonian,
and can contain solids,
which can come out
of solution as the flow
time is being measured.
See section 12.5.1 of
the written standard
for information on calculating
kinematic viscosity
of residual fuel oils.
In this particular case, the
viscometer tube calibration
constant, C, equals
0.305 millimeters
squared per second squared.
Using the flow time
measurement from test number
one, 376.66 seconds, calculate
the kinematic viscosity
determination using
the following equation.
376.66 seconds times
0.305 millimeters
squared per seconds squared
equals 114.88 millimeters
squared per second.
Calculate the second kinematic
viscosity determination
using the flow time measurement
from test number two,
390.03 seconds.
390.03 seconds times
0.305 millimeters
squared per seconds squared
equals 118.96 millimeters
squared per second.
Determine the difference between
the two kinematic viscosity
results.
Average kinematic viscosity
determinations 1 and 2.
Use the determinability
calculation
for residual fuel oils
at 50 degrees Celsius
from section 17.1.1 of
the written standard.
0.017 times y, where y is
the average of the determined
values being compared.
0.017 times y equals 0.017
times 116.92 millimeters
squared per second equals 1.98
millimeters squared per second.
Because 4.08 millimeters
squared per second
is greater than 1.98
millimeters squared per second,
the measurements are considered
to not meet ASTM D445
determinability for
this material type,
and the results should
not be reported.
The operator must repeat the
measurements of flow times
after a thorough cleaning
and drying of the viscometers
and filtering of the sample
as per section 12.5.1
of the written standard.