1、Designation: D7525 14Standard Test Method forOxidation Stability of Spark Ignition FuelRapid SmallScale Oxidation Test (RSSOT)1This standard is issued under the fixed designation D7525; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This laboratory test method covers the quantitativedetermination of the stability of spark ignition fu
3、el, includingthose containing alcohols or other oxygenates, under acceler-ated oxidation conditions, by an automatic instrument(WarningThis test method is not intended for determiningthe stability of gasoline components, particularly those with ahigh percentage of low boiling unsaturated compounds,
4、asthese can cause explosive conditions with the apparatus.2)1.2 This test method measures the induction period, underspecified conditions, which can be used as an indication of theoxidation and storage stability of spark ignition fuel.1.3 The values stated in SI units are to be regarded asstandard.
5、No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bi
6、lity of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD6300 Practice for Determination of Precision and BiasData for Use in Te
7、st Methods for Petroleum Products andLubricants3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 break point, npressure in the test apparatus, which is10 % below the maximum pressure of the actual test run.3.1.2 induction period, ntime elapsed between starting theheating procedu
8、re of the sample vessel and the break point,measured in minutes.4. Summary of Test Method4.1 A 5 mL sample is introduced into a pressure vesselwhich is then charged with oxygen to 500 kPa at a temperatureof 15 to 25C. The test is initiated by starting the heater andheating the pressure vessel to a t
9、emperature of 140C.4.2 The pressure is recorded continuously until the break-point is reached.Alternatively, the test may be terminated whena predetermined minimum requirement is reached.5. Significance and Use5.1 The induction period may be used as an indication of theoxidation and storage stabilit
10、y of spark ignition fuel.5.2 Compared to some other oxidation and storage stabilitytest methods, this test method uses a small sample and gives aresult in a short time period.6. Apparatus6.1 GeneralThis test method uses an automatically con-trolled oxidation tester4(Fig. 1) comprising an oxidationpr
11、essure vessel containing a test sample cup capable of beingrapidly heated, fitted with a pressure sensor capable of mea-suring pressures up to 2000 kPa and a temperature sensorcapable of reading to 0.1C. Pressure and temperature in theoxidation vessel are recorded continuously during the test. Theox
12、idation pressure vessel is fitted with filling and relief valvesand a means of automatically releasing the pressure at the endof the test. The integrated cooling fan cools the pressure vessel1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lub
13、ricants and is the direct responsibility ofSubcommittee D02.14 on Stability and Cleanliness of Liquid Fuels.Current edition approved Oct. 1, 2014. Published November 2014. Originallyapproved in 2009. Last previous edition approved in 2009 as D7525 09. DOI:10.1520/D7525-14.2Further information can be
14、 found in the June 1978, January 1979, and June1986 editions of the Institute of Petroleum Review.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Docu
15、ment Summary page onthe ASTM website.4The sole source of supply of the apparatus known to the committee at this timeis Anton Paars PetroOxy apparatus, available from Anton Paar ProveTec GmbH,Ludwig-Erhard-Ring 13, 15827 Blankenfelde-Mahlow, Germany, www.anton-. If you are aware of alternative suppli
16、ers, please provide this informationto ASTM International Headquarters. Your comments will receive careful consid-eration at a meeting of the responsible technical committee,1which you may attend.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr
17、Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1from the test temperature to ambient temperature by a flow ofair. See Annex A1 for detailed information.6.2 Volumetric Device, clean and free from contaminationsof previous samples, capable of delivering 5.0 6 0.1 mL.6.3 Temp
18、erature Calibration Equipment, comprising acover and a temperature calibration sensor (Fig. 2). Thetemperature calibration sensor is fixed to a depth of 15 6 0.5mm. The temperature calibration sensor, calibrated to the1. Unlocking mechanism for insulating hood2. Safety and insulating hood3. Screw ca
19、p for closing the test container4. Oxygen outlet5. Oxygen inlet6. “O-ring” seal for test sample cup7. Test sample cup8. Locking mechanism for insulating hood9. Operating panel with displayFIG. 1 Schematic of Apparatus for Rapid Small Scale Oxidation TestD7525 142nearest 0.1C, is calibrated by an app
20、roved calibration service,such as one that is traceable to the National Institute ofStandards and Technology (NIST) or to a national authority inthe country in which the equipment is used or manufactured.6.4 Pressure Calibration Equipment, comprising a pressurecalibration sensor (Fig. 3). The pressu
21、re calibration senor iscalibrated to the nearest 10 kPa, by an approved calibrationservice, such as one that is traceable to the National Institute ofStandards and Technology (NIST) or to a national authority inthe country in which the equipment is used or manufactured.7. Reagents and Materials7.1 S
22、olvent for the removal of oxidation residues from thetest vessel. The solvent shall be of suitable purity to leave noresidue on the apparatus. Ethanol of 94 % minimum purity hasbeen found to be suitable. Other solvents, such as a mixture of1. Calibration cover with duct for temperature calibration s
23、ensor2. Calibration fluid3. Temperature sensor for block temperature4. Heating block5. Immersion depth of temperature calibration sensor and bottom ofcalibration cover6. Seal7. Temperature calibration sensor8. Connector plug to measuring deviceFIG. 2 Temperature Calibration EquipmentD7525 143equal v
24、olumes of toluene and acetone, may be used if shown tomeet the requirements for the removal of oxidation residuesfrom the test vessel without leaving any residue in the sampletest cup.7.2 OxygenCommercially available extra-dry oxygen ofnot less than 99.6 % purity.7.3 Lint-Free Cleaning TissueFor sen
25、sitive surfaces; thatwill not scratch the surface.7.4 “O-ring” SealSee A1.2.7.5 Temperature Calibration FluidStable middle distillatefuel liquid with flash point above +60C and boiling-pointabove +150C.8. Hazards8.1 (WarningTo provide protection against possible ex-plosive rupture of the pressure ve
26、ssel and hazards relating tohot and flammable fuels, the apparatus shall be operated behindan appropriate safety shield.)9. Sampling9.1 Sample in accordance with Practices D4057 or D4177.10. Preparation of Apparatus10.1 Remove the previous sample by means of a pipette orsimilar device.10.2 Remove th
27、e used “O-ring” seal and discard.FIG. 3 Pressure Calibration EquipmentD7525 144NOTE 1To avoid contamination of the new test, it is necessary todiscard the used “O-ring” seal, because it might be soaked with oxidationproducts from the previous test.10.3 Wipe the test sample cup, the seal groove and t
28、he coverof the test vessel with lint-free cleaning tissue (7.3) soakedwith solvent until free of gum or other oxidation residues.10.4 Allow the test sample cup and cover to dry in air andvisually inspect for cleanliness.NOTE 2Compressed air is generally unsuitable to speed up evapora-tion of solvent
29、 because it can contain traces of oil that could contaminatethe next test.10.5 Insert a new “O-ring” seal.11. Calibration11.1 Recalibrate the tester every 12 months for correcttemperature and pressure detection.11.2 Calibration of temperature indicator.11.2.1 Calibrate the temperature sensor (A1.6)
30、to the nearest0.1C using the temperature calibration equipment (6.3) ac-cording to A2.1.11.3 Calibration of pressure detector.11.3.1 Calibrate the pressure sensor (A1.5) to the nearest 10kPa, using the pressure calibration equipment (6.4) accordingto A2.2.11.4 Verify, at least every 3 months, that t
31、he heater isoperating properly and the pressure vessel is reaching 140 60.5C within 5 min.12. Procedure12.1 Switch the apparatus on. Bring the pressure vessel andthe spark ignition fuel sample to be tested to a temperature of15 to 25C.12.2 Using a volumetric device (6.2), place 5 6 0.1 mL ofthe samp
32、le into the test sample cup (Fig. 1, No. 7).12.3 Cover the test sample cup with the screw-cap (Fig. 1,No. 3), and close the pressure vessel.12.4 Introduce oxygen (7.2) into the pressure vessel until apressure of 500 6 5 kPa is attained and stabilized over 20 s.12.5 Start the heater with no delay bet
33、ween charging withoxygen and starting the test. The apparatus automatically startsthe timer.12.6 The apparatus brings the oxidation pressure vessel andtest specimen to 140 6 0.5C within 5 min.12.7 If, during the initial 5 min of the test, a steady drop inpressure is observed, discontinue the test an
34、d discard the testspecimen.12.7.1 Under no circumstances may the leakage rate exceeda value of 2 kPa/h. If the leakage rate shows an increase, checkthe following components:O-ring for damage or residues of samples,Surface of the sample cup for damage, andSample cup for sample residues.12.7.2 Contact
35、 the manufacturer to resolve leakage prob-lems from other parts of the instrument.12.8 The apparatus automatically records the temperature(to the nearest 0.1C) and pressure (to the nearest 1 kPa) of theoxidation vessel continuously.12.9 The test apparatus will automatically terminate the testwhen th
36、e pressure readings show a 10% drop from themaximum observed pressure. This is the breakpoint.12.10 Record the induction period to the nearest 1 min.12.11 Alternatively, terminate the test when the test timeexceeds a predetermined minimum requirement.NOTE 3The apparatus will automatically switch on
37、the fan to cool thepressure vessel to approximately room temperature. When the apparatushas cooled sufficiently, the apparatus automatically releases the pressureslowly from the pressure vessel through the valve at a rate not exceeding345 kPa/min.12.12 When the pressure release process has finished,
38、 openthe apparatus and clean according to Section 10.13. Report13.1 Report the induction period to the nearest wholeminute, and reference this test method. If the test was stopped(12.11) prior to observing the pressure drop required in 12.9,report induction period (referencing this test method) as g
39、reaterthan N minutes, where N is the predetermined minimum timewithin the induction period.14. Precision and Bias14.1 The precision statement was determined in an inter-laboratory study (#0542) in 2011 with seven participatinglaboratories and eleven samples.14.1.1 RepeatabilityThe difference between
40、 successivetest results, obtained by the same operator using the sameapparatus under constant operating conditions on identical testmaterial, would in the long run, in the normal and correctoperation of this test method, exceed the following only in onecase in twenty.r 5 0.3903 X0.6(1)where:X = the
41、mean of the two test results expressed in minutes,rounded to the nearest 0.01 min.NOTE 4The degrees of freedom associated with the repeatabilityestimate from this round robin study are 29. Since the minimumrequirement of 30 (in accordance with Practice D6300) is not met, usersare cautioned that the
42、actual repeatability may be significantly differentthan these estimates.14.1.2 ReproducibilityThe difference between two singleand independent test results obtained by different operatorsworking in different laboratories, on identical material, wouldin long run, in the normal and correct operation o
43、f this testmethod, exceed the following only in one case in twenty.R 5 1.0212 X0.6(2)where:X = the mean of the two test results expressed in minutes,rounded to the nearest 0.01 min.NOTE 5Supporting data have been filed at ASTM InternationalD7525 145Headquarters and may be obtained by requesting Rese
44、arch ReportRR:D02-1783.514.2 BiasSince the value of oxidation stability measuredby this test method is defined solely by this test method, nostatement of bias can be made.15. Keywords15.1 breakpoint; gasoline; induction period; oxidation sta-bility; oxygen uptake; spark ignition fuelANNEXES(Mandator
45、y Information)A1. AUTOMATICALLY CONTROLLED OXIDATION TESTERA1.1 Pressure Vessel and ClosureA1.1.1 Internal volume without sample: 20 mL. Inner di-ameter: 47 6 0.15 mm.A1.1.2 Made of corrosion-resistant material and constructedto withstand a working pressure of 1800 kPa.A1.1.3 Interior surfaces: smoo
46、th (polished), chemically in-ert surface to facilitate cleaning and prevent corrosion.A1.2 “O-ring”A1.2.1 Seal for Test Sample CupMade of material beingresistant to oxygen, spark ignition fuel components and heat,typically fluoro-elastomer FPM/FKM (commonly known asViton6), coated with PTFE.A1.3 Hea
47、tingA1.3.1 Installed power rating: 500 W. Typically electricheating, near the bottom of the pressure vessel, to facilitate bestheat transfer to the sample.A1.3.2 The heater control shall be capable of maintainingthe test cup temperature within 60.5C at the test temperaturesof 140C.A1.4 ValvesA1.4.1
48、Solenoid valves with small dead volume and orificesizes and short cycling rates.A1.5 Pressure SensorA1.5.1 Absolute or relative pressure transducer.A1.5.2 Pressure Range0 to 2000 kPa (minimum).A1.5.3 Accuracy63 % full-scale span.A1.5.4 Typical Sensitivity1 to 25 mV/kPa.A1.6 Temperature SensorA1.6.1
49、Platinum Resistance Thermometeraccuracy 6(0.1 + 0.0017 x (t), where (t) is the actual temperature in C,range up to 200C.A1.7 Connecting PipesA1.7.1 Small orifices, typical inner diameter: 0.5 to 1.0 mm.A1.8 Cooling FanA1.8.1 Capable of cooling the pressure vessel from the testtemperature to ambient temperature by applying a stream of airto the outside of the pressure vessel.A1.9 General RequirementsA1.9.1 All equipment in contact with the sample andoxygen shall be made of corrosion-resistant materials.A1.9.2 The pressure vessel
