ASTM D7525-09

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D7525 − 09
StandardTest Method for
Oxidation Stability of Spark Ignition Fuel—Rapid Small
Scale Oxidation Test (RSSOT)
This standard is issued under the fixed designation D7525; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.1 break point, n—pressureinthetestapparatus,whichis
10 % below the maximum pressure of the actual test run.
1.1 This laboratory test method covers the quantitative
3.1.2 induction period, n—timeelapsedbetweenstartingthe
determination of the stability of spark ignition fuel, including
heating procedure of the sample vessel and the break point,
those containing alcohols or other oxygenates, under acceler-
measured in minutes.
ated oxidation conditions, by an automatic instrument
(Warning—This test method is not intended for determining
4. Summary of Test Method
the stability of gasoline components, particularly those with a
high percentage of low boiling unsaturated compounds, as
4.1 A 5 mL sample is introduced into a pressure vessel
these can cause explosive conditions with the apparatus. ) which is then charged with oxygen to 500 kPa at a temperature
of 15 to 25°C. The test is initiated by starting the heater and
1.2 This test method measures the induction period, under
heating the pressure vessel to a temperature of 140°C.
specified conditions, which can be used as an indication of the
oxidation and storage stability of spark ignition fuel.
4.2 The pressure is recorded continuously until the break-
pointisreached.Alternatively,thetestmaybeterminatedwhen
1.3 The values stated in SI units are to be regarded as
a predetermined minimum requirement is reached.
standard. No other units of measurement are included in this
standard.
5. Significance and Use
1.4 This standard does not purport to address all of the
5.1 Theinductionperiodmaybeusedasanindicationofthe
safety concerns, if any, associated with its use. It is the
oxidation and storage stability of spark ignition fuel.
responsibility of the user of this standard to establish appro-
5.2 Compared to some other oxidation and storage stability
priate safety and health practices and determine the applica-
test methods, this test method uses a small sample and gives a
bility of regulatory limitations prior to use.
result in a short time period.
2. Referenced Documents
6. Apparatus
2.1 ASTM Standards:
6.1 General—This test method uses an automatically con-
D4057 Practice for Manual Sampling of Petroleum and
trolled oxidation tester (Fig. 1) comprising an oxidation
Petroleum Products
pressure vessel containing a test sample cup capable of being
D4177 Practice for Automatic Sampling of Petroleum and
rapidly heated, fitted with a pressure sensor capable of mea-
Petroleum Products
suring pressures up to 2000 kPa and a temperature sensor
capable of reading to 0.1°C. Pressure and temperature in the
3. Terminology
oxidation vessel are recorded continuously during the test. The
3.1 Definitions of Terms Specific to This Standard:
oxidation pressure vessel is fitted with filling and relief valves
and a means of automatically releasing the pressure at the end
of the test.The integrated cooling fan cools the pressure vessel
This test method is under the jurisdiction of ASTM Committee D02 on
from the test temperature to ambient temperature by a flow of
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
air. See Annex A1 for detailed information.
D02.14 on Stability and Cleanliness of Liquid Fuels.
Current edition approved April 15, 2009. Published May 2009. DOI: 10.1520/
D7525-09.
2 4
Further information can be found in the June 1978, January 1979, and June The sole source of supply of the apparatus known to the committee at this time
1986 editions of the Institute of Petroleum Review. is Petrotest PetroOXY apparatus, available from Petrotest. Instruments GmbH &
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Co, Ludwig-Erhard-Ring 13, 15827 Dahlewitz, Germany, www.petrotest.com. If
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM you are aware of alternative suppliers, please provide this information to ASTM
Standards volume information, refer to the standard’s Document Summary page on International Headquarters. Your comments will receive careful consideration at a
the ASTM website. meeting of the responsible technical committee, which you may attend.
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D7525 − 09
1. Unlocking mechanism for insulating hood
2. Safety and insulating hood
3. Screw cap for closing the test container
4. Oxygen outlet
5. Oxygen inlet
6. “O-ring” seal for test sample cup
7. Test sample cup
8. Locking mechanism for insulating hood
9. Operating panel with display
FIG. 1 Schematic of Apparatus for Rapid Small Scale Oxidation Test
6.2 Volumetric Device, clean and free from contaminations Standards and Technology (NIST) or to a national authority in
of previous samples, capable of delivering 5.0 6 0.1 mL. the country in which the equipment is used or manufactured.
6.3 Temperature Calibration Equipment, comprising a 6.4 Pressure Calibration Equipment, comprising a pressure
cover and a temperature calibration sensor (Fig. 2). The calibration sensor (Fig. 3). The pressure calibration senor is
temperature calibration sensor is fixed to a depth of 15 6 0.5 calibrated to the nearest 10 kPa, by an approved calibration
mm. The temperature calibration sensor, calibrated to the service, such as one that is traceable to the National Institute of
nearest 0.1°C, is calibrated by an approved calibration service, Standards and Technology (NIST) or to a national authority in
such as one that is traceable to the National Institute of the country in which the equipment is used or manufactured.
D7525 − 09
1. Calibration cover with duct for temperature calibration sensor
2. Calibration fluid
3. Temperature sensor for block temperature
4. Heating block
5. Immersion depth of temperature calibration sensor and bottom of
calibration cover
6. Seal
7. Temperature calibration sensor
8. Connector plug to measuring device
FIG. 2 Temperature Calibration Equipment
7. Reagents and Materials 7.2 Oxygen—Commercially available extra-dry oxygen of
not less than 99.6 % purity.
7.1 Solvent for the removal of oxidation residues from the
test vessel. The solvent shall be of suitable purity to leave no
7.3 Lint-Free Cleaning Tissue—For sensitive surfaces; that
residue on the apparatus. Ethanol of 94 % minimum purity has
will not scratch the surface.
been found to be suitable. Other solvents, such as a mixture of
7.4 “O-ring” Seal—See A1.2.
equalvolumesoftolueneandacetone,maybeusedifshownto
meet the requirements for the removal of oxidation residues 7.5 Temperature Calibration Fluid—Stable middle distillate
from the test vessel without leaving any residue in the sample fuel liquid with flash point above +60°C and boiling-point
test cup. above +150°C.
D7525 − 09
FIG. 3 Pressure Calibration Equipment
NOTE 1—To avoid contamination of the new test, it is necessary to
8. Hazards
discard the used “O-ring” seal, because it might be soaked with oxidation
8.1 (Warning—To provide protection against possible ex-
products from the previous test.
plosive rupture of the pressure vessel and hazards relating to
10.3 Wipethetestsamplecup,thesealgrooveandthecover
hotandflammablefuels,theapparatusshallbeoperatedbehind
of the test vessel with lint-free cleaning tissue (7.3) soaked
an appropriate safety shield.)
with solvent until free of gum or other oxidation residues.
9. Sampling
10.4 Allow the test sample cup and cover to dry in air and
9.1 Sample in accordance with Practices D4057 or D4177.
visually inspect for cleanliness.
10. Preparation of Apparatus
NOTE 2—Compressed air is generally unsuitable to speed up evapora-
10.1 Remove the previous sample by means of a pipette or tion of solvent because it can contain traces of oil that could contaminate
the next test.
similar device.
10.2 Remove the used “O-ring” seal and discard. 10.5 Insert a new “O-ring” seal.
D7525 − 09
11. Calibration 12.7.2 Contact the manufacturer to resolve leakage prob-
lems from other parts of the instrument.
11.1 Recalibrate the tester every 12 months for correct
temperature and pressure detec
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