ASTM D6468-99(2004)
(Test Method)Standard Test Method for High Temperature Stability of Distillate Fuels
Standard Test Method for High Temperature Stability of Distillate Fuels
SCOPE
1.1 This test method covers relative stability of middle distillate fuels under high temperature aging conditions with limited air exposure. This test method is suitable for all No. 1 and No. 2 grades in Specifications D 396, D 975, D 2880, and for grades DMS and DMA in Specification D 2069. It is also suitable for similar fuels meeting other specifications.
1.2 This test method is not suitable for fuels whose flash point, as determined by Test Methods D 56, D 93, or D 3828, is less than 38°C. This test method is not suitable for fuels containing residual oil.
1.3 The values stated in SI units are to be regarded as the standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
An American National Standard
Designation: D 6468 – 99 (Reapproved 2004)
Standard Test Method for
High Temperature Stability of Distillate Fuels
This standard is issued under the fixed designation D 6468; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 4057 Practice for Manual Sampling of Petroleum and
Petroleum Products
1.1 This test method covers relative stability of middle
D 4625 Test Method for Distillate Fuel Storage Stability at
distillate fuels under high temperature aging conditions with
43°C
limited air exposure. This test method is suitable for all No. 1
D 5452 Test Method for Particulate Contamination inAvia-
and No. 2 grades in Specifications D 396, D 975, D 2880, and
tion Fuels by Laboratory Filtration
D 3699 and for grades DMX and DMA in Specification
D 2069. It is also suitable for similar fuels meeting other
3. Terminology
specifications.
3.1 Definitions of Terms Specific to This Standard:
1.2 This test method is not suitable for fuels whose flash
3.1.1 adherent insolubles—material that is produced in the
point, as determined by Test MethodsD56,D93,or D 3828,
course of stressing distillate fuel and that adheres to the
is less than 38°C. This test method is not suitable for fuels
glassware after fuel has been flushed from the system.
containing residual oil.
3.1.2 filterable insolubles—material that is produced in the
1.3 The values stated in SI units are to be regarded as the
course of stressing distillate fuel and that is capable of being
standard.
removed from the fuel by filtration.
1.4 This standard does not purport to address all of the
3.1.3 inherent stability—the resistance to change when
safety concerns, if any, associated with its use. It is the
exposed to air, but in the absence of other environmental
responsibility of the user of this standard to establish appro-
factors such as water, reactive metal surfaces, and dirt.
priate safety and health practices and determine the applica-
3.1.4 storage stability—the resistance of fuel to formation
bility of regulatory limitations prior to use.
of degradation products when stored at ambient temperatures.
2. Referenced Documents 3.1.5 thermal stability—the resistance of fuel to formation
of degradation products when thermally stressed.
2.1 ASTM Standards:
D56 Test Method for Flash Point by Tag Closed Tester
4. Summary of Test Method
D93 Test Methods for Flash Point by Pensky-Martens
4.1 Two 50-mLvolumes of filtered middle distillate fuel are
Closed Cup Tester
aged for 90 or 180 min at 150°C in open tubes with air
D 396 Specification for Fuel Oils
exposure.After aging and cooling, the fuel samples are filtered
D 975 Specification for Diesel Fuel Oils
and the average amount of filterable insolubles is estimated by
D 1500 Test Method for ASTM Color of Petroleum Prod-
measuring the light reflectance of the filter pads. The 100 and
ucts (ASTM Color Scale)
0 % extremes of the reflectance rating range are defined by an
D 2069 Specification for Marine Fuels
unused filter pad and a commercial black standard, respec-
D 2274 Test Method for Oxidation Stability of Distillate
tively.
Fuel Oil (Accelerated Method)
D 2880 Specification for Gas Turbine Fuel Oils
5. Significance and Use
D 3699 Specification for Kerosine
5.1 This test method provides an indication of thermal
D 3828 TestMethodsforFlashPointbySmallScaleClosed
oxidative stability of distillate fuels when heated to high
Tester
temperatures that simulate those that may occur in some types
of recirculating engine or burner fuel delivery systems. Results
This test method is under the jurisdiction of ASTM Committee D02 on
have not been substantially correlated to engine or burner
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
operation. The test method can be useful for investigation of
D02.14 on Stability and Cleanliness of Liquid Fuels.
operational problems related to fuel thermal stability.
Current edition approved Nov. 1, 2004. Published November 2004. Originally
approved in 1999. Last previous edition approved in 1999 as D 6468 – 99.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Henry, C. P., “The du Pont F21 149°C (300°F) Accelerated Stability Test,”
Standards volume information, refer to the standard’s Document Summary page on Distillate Fuel Stability and Cleanliness, ASTM STP 751, L. L. Stavinoha and C. P.
the ASTM website. Henry, Eds., ASTM, 1981, pp. 22-33.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
D 6468 – 99 (2004)
5.2 When the test method is used to monitor manufacture or shouldriseto27kPawithin10to15safterthesampleisadded
storage of fuels, changes in filter rating values can indicate a to the filtration funnel.
relative change in inherent stability. Storage stability predic-
NOTE 2—Use of reduced vacuum improves retention of particulate on
tions are more reliable when correlated to longer-term storage
the relatively porous filter media.
tests, for example, Test Method D 4625, or other lower
6.6 Reflection meter, Photovolt Model 577 Digital Reflec-
temperature, long-term tests. When fuel samples are freshly
tion Meter, complete with search unit Y with a green filter and
produced, aging for 180 min, instead of the traditional 90-min
polished black glass standard.
interval, tends to give a result correlating more satisfactorily
with the above methods (see Appendix X2).
NOTE 3—Other reflection meters or search units, or both, can be used,
5.3 The test method uses a filter paper with a nominal
but they are likely to provide only similar (not identical) results. For
porosity of 11 µm, which will not capture all of the sediment
example, Photovolt Model 577 digital reflection meter equipped with
formed during aging but allows differentiation over a broad
search unit W usually gives somewhat lower percent reflectance values.
range. Reflectance ratings are also affected by the color of Correlation of these values is discussed in Appendix X1.
filterableinsolubles,whichmaynotcorrelatetothemassofthe NOTE 4—Olderreflectionmeters,includingbutnotlimitedtoPhotovolt
Model 670 analog meter, are satisfactory.
material filtered from the aged fuel sample. Therefore, no
quantitative relationship exists between the pad rating and the
7. Reagents and Materials
gravimetric mass of filterable insolubles.
7.1 Purity of Reagents—Reagent grade chemicals shall be
6. Apparatus
used in all tests. Unless otherwise indicated, it is intended that
6.1 Aging Tubes,253 200 mm, heavy wall test tubes made
all reagents conform to the specifications of the Committee on
of borosilicate glass.
Analytical Reagents of the American Chemical Society where
6.2 Heating Bath, with liquid heating medium, thermostati-
such specifications are available. Other grades may be used,
callycontrolledtomaintainthesampleintheagingtubewithin
provided it is first ascertained that the reagent is of sufficiently
1.5°C of 150°C. It must be large enough to hold aging tubes
high purity to permit its use without lessening the accuracy of
immersed in the heating liquid to a depth above the level of
the determination.
samples in the tubes. The bath and its location shall be such to
7.2 Acetone, reagent grade. (Warning—Extremely flam-
enable shielding of the samples from direct light during aging.
mable.)
Thevolumeofbathanditsheatrecoveryrateshallbesuchthat
7.3 Adherent Insolubles Solvent (Trisolvent or TAM),a
the temperature of the medium does not drop more than 5°C
mixture of equal parts by volume of reagent grade toluene
when the maximum number of aging tubes are inserted, and
(Warning—Flammable. Vapor harmful.), acetone
recovery to 150°C shall not require more than 15 min.
(Warning—see 7.2), and methanol (Warning—Flammable.
(Warning—The flash point of the liquid heating medium must
Vapor Harmful. May be fatal or cause blindness if swallowed
be at least 180°C. Bath vapors and oil sample vapors shall be
or inhaled. Cannot be made nonpoisonous.).
properlyvented.Exposedhotsurfacesontheapparatusandhot
7.4 Hydrocarbon Solvent, 2,2,4-trimethylpentane (iso-
heating medium can cause severe burns.)
octane), 99.75 % purity minimum (Warning—see 7.2).
6.3 Thermometer, either glass or digital, whose accuracy in
the 140 to 160°C range is certified or traceable to a certified
NOTE 5—Heptane is a satisfactory alternative hydrocarbon solvent.
thermometer. Use to monitor the temperature of the heating
However,smalldifferencesmaybeseenduetoslightlydifferentsolubility
bath in 6.2.
characteristics. Iso-octane is specified to be in agreement with the
6.4 Membrane Filter Holder,tofit47-mmmembranefilters, hydrocarbon solvent used in other middle distillate stability test methods
such as Test Methods D 2274 and D 4625.
fitted to a heavy-walled 500-mL or 1-L vacuum flask.
7.5 Filter Paper (Filter Pad), Whatman No. 1, 47-mm
NOTE 1—Several types of membrane filter holders are available. To
reduce electrostatic hazards, an all metal filter holder equipped with diameter, or equivalent.
grounding cables is recommended. Such an apparatus and correct
NOTE 6—Filter papers of 42.5 or 55-mm diameter are technically
grounding practices are described in Test Method D 5452. A fritted glass
satisfactory. Filters with a diameter of 47 mm permit a small unused
filter holder is less preferred because of a tendency to become partially
margin for identifying the sample and fit all filtration apparatuses.
cloggedduringusesothatfilterpadsthatdonothaveuniformdepositsare
obtained. Glass filter holders that use a 75-µm (200-mesh) screen to
support the filter are available; however, since the screen can be an
unbonded electrostatic charge collector, these are not recommended for
use with flammable liquids.
The sole source of supply of the apparatus known to the committee at this time
is available from UMM Electronics Inc., Photovolt Instruments, 6911 Hillsdale
6.5 Vacuum Source, that limits the maximum vacuum to 27
Court,Indianapolis,IN46250-2062.Ifyouareawareofalternativesuppliers,please
kPa (200 mm Hg) below atmospheric pressure. The vacuum
provide this information toASTM International Headquarters. Your comments will
receive careful consideration at a meeting of the responsible technical committee ,
which you may attend.
4 6
The sole source of supply of the apparatus known to the committee at this time Reagent Chemicals, American Chemical Society Specifications, American
is a suitable filter holder available from Millipore Corporation, 80 Ashby Rd., Chemical Society, Washington, DC. For suggestions on the testing of reagents not
Bedford, MA 01730; Catalog No. XX20 047 20. If you are aware of alternative listed by the American Chemical Society, see Analar Standards for Laboratory
suppliers, please provide this information to ASTM International Headquarters. Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Your comments will receive careful consideration at a meeting of the responsible and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
technical committee , which you may attend. MD.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
D 6468 – 99 (2004)
8. Sampling 11. Procedure
8.1 When samples of a fuel batch are obtained to determine 11.1 Adjusttheheatingbathtoatemperatureof15061.5°C
stability, obtain samples in accordance with Practice D 4057. (see 6.3).
Use only epoxy-lined cans or borosilicate glass bottles. Shield 11.2 Assemble the filter apparatus with a new filter paper.
clear glass bottles from sunlight to prevent photochemical Filteratleast100mLofthefuelsamplethroughthepaper.Use
reactions. the inline vacuum regulator so that the maximum vacuum is 27
8.2 When samples are from a fuel or component rundown kPa(200mmHg).Measuretwo50 62-mLvolumesoffiltered
line, exercise care to ensure that the sampling line and valving fuel and decant into each of two aging tubes (see Appendix
are thoroughly flushed with current mainstream sample. X3).
8.3 Because stability of some fuels, as determined in this
NOTE 9—Where practical, filter a fuel sample larger than 100 mL. This
test method, changes over time, the sampling date shall be
will reduce the possibility that the paper may absorb trace materials that
recorded; record time and date if sample is from a fuel or
affect stability.
component rundown line. Samples should be stored at tem-
11.3 Placetheuncappedsampletubesintheheatingbathfor
peratures below 5°C. If storage for more than a few days is
90 6 3 min, or 180 6 5 min. Place the tubes in the bath in the
expected, oxygen should be removed from the fuel by subsur-
sameorderinwhichtheyaretoberemoved.(Warning—Fuels
face purging with a stream of nitrogen; for example, by
will be heated above their flash points. There is a possibility
bubbling nitrogen for 1 min/L of sample.
that certain light fuels such as kerosine will boil under
conditionsofthetest.Bothsituationsraisetheriskoffirewhen
9. Preparation of Apparatus
an ignition source is present. Fuel samples that may contain
9.1 CleaningAging Tubes—Cleannewtubesusingadherent
gasoline or other volatile components should not be tested.)
insolubles solvent, then with a mildly alkaline or neutral
laboratory detergent, followed by copious rinsing with deion-
NOTE 10—Theseverityofthetestisincreasedbyagingforlongertimes
ized or distilled water to remove all traces of detergent. Then at 150°C. The selection of the aging time depends on application and
should be established by correlation with other tests or with application
rinse with acetone and air dry. Rinse used tubes with adherent
requirements.
insolubles solvent, dry, then clean as above for new tubes.
Visually inspect tubes before use, and reclean or reject if there
11.4 Removethesamplesfromtheheatingbathandallowto
is the slightest trace of contamination.
cool gradually in air to 20 to 25°C over a period of 90 min to
9.1.1 Because of the small sample size and the high surface
4 h. Cool in the dark to prevent photochemical reactions. Do
to volume ratio in this test method, carefully avoid carry-over
not accelerate cooling by immersing in a cooling bath as this
from past tests or from cl
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