1、Designation: D 7525 09Standard Test Method forOxidation Stability of Spark Ignition FuelRapid SmallScale Oxidation Test (RSSOT)1This standard is issued under the fixed designation D 7525; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, 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. Scope1.1 This laboratory test method covers the quantitativedetermination of the stability of spark ignition f
3、uel, 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-b
6、ility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4177 Practice for Automatic Sampling of Petroleum andPetroleum Products3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.
7、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 startingthe heating procedure of the sample vessel and the break point,measured in minutes.4. Summary of Test Method4.1 A 5 mL sample is introd
8、uced 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 temperature of 140C.4.2 The pressure is recorded continuously until the break-point is reached.Alternatively, the tes
9、t 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 stability of spark ignition fuel.5.2 Compared to some other oxidation and storage stabilitytest methods, this test method us
10、es 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 oxidationpressure vessel containing a test sample cup capable of beingrapidly heated, fitted with a pressure sensor capable of
11、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. Theoxidation pressure vessel is fitted with filling and relief valvesand a means of automatically releasing the pressure
12、at the endof the test. The integrated cooling fan cools the pressure vesselfrom 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.1This te
13、st method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.14 on Stability and Cleanliness of Liquid Fuels.Current edition approved April 15, 2009. Published May 2009.2Further information can be found in the June
14、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 Document Summary page o
15、nthe ASTM website.4The sole source of supply of the apparatus known to the committee at this timeis Petrotest PetroOXY apparatus, available from Petrotest. Instruments GmbH thatwill not scratch the surface.7.4 “O-ring” SealSee A1.2.7.5 Temperature Calibration FluidStable middle distillatefuel liquid
16、 with flash point above +60C and boiling-pointabove +150C.8. Hazards8.1 (WarningTo provide protection against possible ex-plosive rupture of the pressure vessel and hazards relating tohot and flammable fuels, the apparatus shall be operated behindan appropriate safety shield.)1. Calibration cover wi
17、th duct for temperature calibration sensor2. 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
18、Calibration EquipmentD75250939. Sampling9.1 Sample in accordance with Practices D 4057 or D 4177.10. Preparation of Apparatus10.1 Remove the previous sample by means of a pipette orsimilar device.10.2 Remove the used “O-ring” seal and discard.NOTE 1To avoid contamination of the new test, it is neces
19、sary 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 the coverof the test vessel with lint-free cleaning tissue (7.3) soakedwith solvent until free of gum or other oxidation residues.10.4 Al
20、low 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 because it can contain traces of oil that could contaminatethe next test.10.5 Insert a new “O-ring” seal.11. Calibration11.1 Recalibrat
21、e 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) 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 Cal
22、ibrate the pressure sensor (A1.5) to the nearest 10kPa, using the pressure calibration equipment (6.4) accordingto A2.2.FIG. 3 Pressure Calibration EquipmentD752509411.4 Verify, at least every 3 months, that the heater isoperating properly and the pressure vessel is reaching 140 60.5C within 5 min.1
23、2. 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 sample into the test sample cup (Fig. 1, No. 7).12.3 Cover the test sample cup with the screw-c
24、ap (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 between charging withoxygen and starting the test. The apparatus automatically startsthe timer
25、.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 and discard the testspecimen.12.7.1 Under no circumstances may the leakage rate exceeda value
26、 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 the manufacturer to resolve leakage prob-lems from other parts of the instrument.12.8 The
27、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 the pressure readings show a 10% drop from themaximum observed pressure. This is the breakpoi
28、nt.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 the fan to cool thepressure vessel to approximately room temperature. When the apparatushas
29、 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, openthe apparatus and clean according to Section 10.13. Report13.1 Report the induction pe
30、riod 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 greaterthan N minutes, where N is the predetermined minimum timewithin the induction period.
31、14. Precision and Bias14.1 The precision of the test method has not yet beendetermined by a formal interlaboratory study. Preliminaryexaminations for repeatability have shown a value of “r”= 2.4min as interim precision.14.1.1 ReproducibilityThe reproducibility of this testmethod is being determined
32、and will be available in or before2013.14.2 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 fuelA
33、NNEXES(Mandatory 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
34、 surfaces: smooth (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 asViton5), coated wit
35、h PTFE.A1.3 HeatingA1.3.1 Installed power rating: 500 W. Typically electricheating, near the bottom of the pressure vessel, to facilitate bestheat transfer to the sample.5Registered trademark of DuPont Performance Elastomers, 300 BellevueParkway, Suite 300, Wilmington, DE 19809.D7525095A1.3.2 The he
36、ater control shall be capable of maintainingthe test cup temperature within 60.5C at the test temperaturesof 140C.A1.4 ValvesA1.4.1 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 Rang
37、e0 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 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, typi
38、cal 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
39、 made of corrosion-resistant materials.A1.9.2 The pressure vessel shall have an over-temperaturesafeguard.A1.9.3 A cooling device for rapid cooling is recommended.A1.9.4 A safety and isolation hood above the pressurevessel closure is recommended (see Fig. 1).A2. INSTRUMENT CALIBRATIONA2.1 Temperatur
40、e CalibrationA2.1.1 Calibrate temperature sensor (A1.6) at ambient andat 140C.A2.1.2 Fill the cup with 10 6 0.1 mL of the calibration fluid(7.5).A2.1.3 Ensure that the temperature calibration sensorsdepth is fixed at 15 6 0.5 mm (Fig. 2, No. 5).A2.1.4 Cover the test sample cup with the temperatureca
41、libration equipment (6.3)(Fig. 2).A2.1.5 When the temperature is stabilized, record the tem-peratures indicated by the temperature sensor () and thetemperature calibration sensor.A2.1.6 Calculate offset and gain according to manufactur-ers manual and change, if required, according to manufactur-ers
42、manual.A2.2 Pressure CalibrationA2.2.1 Calibrate the pressure sensor (A1.5) at two pres-sures.A2.2.2 Cover the empty sample cup with the screw-cap(Fig. 1, No. 3).A2.2.3 Connect the oxygen filling line to the instrument,and pressurize the test cell to 700 kPa.A2.2.4 Close the filling valve, remove th
43、e oxygen fillingline, and replace it by the calibration equipment (Fig. 3)(6.4).A2.2.5 Start the calibration procedure in accordance withthe manufacturers manual.A2.2.6 Open the valve to the pressure calibration sensor.Pressure will slightly drop.A2.2.7 Record the pressures indicated by the pressure
44、sensor (A1.5) and the pressure calibration sensor.A2.2.8 Close the valve to the pressure calibration equip-ment (6.4).A2.2.9 Reduce the pressure in the test cell to approximately20 kPa and open the valve to the calibration equipment.Pressure will slightly increase to 90 to 100 kPa.A2.2.10 Record the
45、 pressures indicated by the pressuresensor (A1.5) and the pressure calibration sensor.A2.2.11 Release the pressure.A2.2.12 Calculate offset and gain in accordance with themanufacturers manual, and change if required by the manu-facturers manual.ASTM International takes no position respecting the val
46、idity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is sub
47、ject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headqua
48、rters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standa
49、rd is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D7525096
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