1、Designation: D 525 05Designation: 40/97An American National StandardBritish Standard 4347Standard Test Method forOxidation Stability of Gasoline (Induction Period Method)1This standard is issued under the fixed designation D 525; the number immediately following the designation indicates the year of
2、original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department
3、of Defense.1. Scope1.1 This test method covers the determination of the stabil-ity of gasoline in finished form only, under accelerated oxida-tion conditions. (WarningThis test method2is not intendedfor determining the stability of gasoline components, particu-larly those with a high percentage of l
4、ow boiling unsaturatedcompounds, as these may cause explosive conditions withinthe apparatus. However, because of the unknown nature ofcertain samples, the pressure vessel assembly shall include asafety burst-disc in order to safeguard the operator.)NOTE 1For measurement of oxidation stability of ga
5、soline by mea-surement of potential gum, refer to Test Method D 873,orIPTestMethod 138.NOTE 2The precision data were developed with gasolines derivedfrom hydrocarbon sources only without oxygenates.1.2 The accepted SI unit of pressure is the kilo Pascal (kPa),and of temperature is C.1.3 This standar
6、d 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-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM
7、 Standards:3D 873 Test Method for Oxidation Stability ofAviation Fuels(Potential Residue Method)D 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsE1 Specification for ASTM Liquid-in-Glass Thermometers2.2 Energy Institute Standards:IP-138 Test Method for Oxidation Stability, Aviat
8、ion Gaso-line4Part IVPetroleum and its Products53. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 break pointthe point in the pressure-time curve thatis preceded by a pressure drop of exactly 14 kPa within 15 minand succeeded by a drop of not less than 14 kPa in 15 min.3.1.2 ind
9、uction periodthe time elapsed between the plac-ing of the pressure vessel in the bath and the break point at100C.4. Summary of Test Method4.1 The sample is oxidized in a pressure vessel initiallyfilled at 15 to 25C with oxygen pressure at 690 to 705 kPa andheated at a temperature between 98 and 102C
10、. The pressure isrecorded continuously or read at stated intervals until thebreakpoint is reached. The time required for the sample toreach this point is the observed induction period at thetemperature of test, from which the induction period at 100Ccan be calculated. (WarningIn addition to other pr
11、ecautions,to provide protection against the possibility of explosiverupture of the pressure vessel, the pressure vessel should beoperated behind an appropriate safety shield.)5. Significance and Use5.1 The induction period may be used as an indication of thetendency of motor gasoline to form gum in
12、storage. It shouldbe recognized, however, that its correlation with the formation1This test 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.This test method
13、has been approved by the sponsoring aommittees and acceptedby the Cooperating Societies in accordance with established procedures.Current edition approved April 1, 2005. Published May 2005. Originallyapproved in 1939. Last previous edition approved in 2001 as D 525 01.2Further information can be fou
14、nd 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 Document
15、 Summary page onthe ASTM website.4Available from Energy Institute, 61 New Cavendish St., London WIM, 8ARU.K.5Aconvenient template for measuring the breakpoint is described in the paper byKorb, E. L., “Induction Period Calculator,” ASTM Bulletin, No. 153, August 1948,pp. 99102.1Copyright ASTM Interna
16、tional, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.of gum in storage may vary markedly under different storageconditions and with different gasolines.6. Apparatus6.1 Oxidation Pressure Vessel, Glass Sample Container andCover, Accessories, Pressure Gage, and O
17、xidation Bath,asdescribed in Annex A1.6.2 Thermometer, having a range as shown as follows andconforming to the requirements as prescribed in SpecificationE1or in the specifications for IP thermometers:NOTE 3Other temperature sensing devices that cover the temperaturerange of interest, such as thermo
18、couples or platinum resistance thermom-eters, that can provide equivalent or better accuracy and precision, may beused in place of thermometers specified in 6.2.Thermometer NumberTemperature Range ASTM IP95 to 103C 22C 24C7. Reagents and Materials7.1 Gum SolventMixture of equal volumes of toluene an
19、dacetone, both of which shall be of 99 % minimum purity.7.2 OxygenCommercially-available extra-dry oxygen ofnot less than 99.6 % purity.8. Sampling8.1 Sample in accordance with the procedure for oxidationstability as described in Practice D 4057.9. Preparation of Apparatus9.1 Wash the glass sample c
20、ontainer with gum solvent untilfree from gum. Rinse thoroughly with water and immerse thesample container and cover in detergent cleaning solution. Thetype of detergent and conditions for its use shall match thecleanliness obtained by the use of a strongly oxidizing agentsuch as chromosulfuric acid,
21、 ammonium peroxydisulfate inconcentrated sulfuric acid at approximately 8 G./L, or sulfuricacid itself, soaking for at least 12 h, followed by rinses in tapwater, distilled water and then acetone. For comparison, visualappearance and weight loss on heating the glassware under testconditions may be u
22、sed. Glassware needs to show no signs ofdiscoloration or particulates on the surface. The weight ofglassware must not change by more than 60.5 mg betweencleaning and heating/cooling cycles. Detergent cleaning avoidsthe potential hazards and inconveniences related to handlingcorrosive chromic acid so
23、lutions; this procedure remains thereference cleaning practice and as such may function as analternate to the preferred procedure, cleaning with detergentsolutions.9.2 Remove container and cover from the cleaning solutionby means of corrosion-resistant steel forceps and handle onlywith forceps there
24、after. Wash thoroughly, first with tap water,then with distilled water, and dry in an oven at 100 to 150C forat least 1 h.9.3 Drain any gasoline from the pressure vessel and wipethe inside of the pressure vessel and pressure vessel closure,first with a clean cloth moistened with gum solvent and then
25、with a clean dry cloth. Remove the filler rod from the stem andcarefully clean any gum or gasoline from the stem, rod, andneedle valve with gum solvent. The pressure vessel, the valve,and all connecting lines shall be thoroughly dry before eachtest is started. (WarningVolatile peroxides which may ha
26、veformed during a previous test may accumulate in the equip-ment, producing a potentially explosive environment. Specialcare in cleaning after each test is needed to ensure the filler rod,stem, and needle valve are free of these peroxides.)10. Procedure10.1 Bring the pressure vessel and the gasoline
27、 to be testedto a temperature of 15 to 25C. Place the glass samplecontainer in the pressure vessel and add 50 6 1 mL of testspecimen. Alternatively, transfer 50 6 1 mL of test specimeninto the glass sample container first, before placing the glasssample container into the pressure vessel. Cover the
28、samplecontainer, close the pressure vessel, and using a quick releaseair coupling introduce oxygen until a pressure of 690 to 705kPa is attained. Allow the gas in the bomb to escape slowly inorder to flush out the air originally present (Release thepressure at a slow uniform rate through the needle
29、valve at arate not to exceed 345 kPa per min). Introduce oxygen againuntil a pressure of 690 to 705 kPa is attained and observe forleaks, ignoring an initial rapid drop in pressure (generally notover 40 kPa) which may be observed because of the solution ofoxygen in the sample. When the rate of press
30、ure drop does notexceed 7 kPa in 10 min, assume the absence of leaks andproceed with the test without repressuring.10.2 Place the charged pressure vessel in the vigorouslyboiling water bath, or appropriate liquid bath equipped withmechanical stirring, being careful to avoid shaking, and recordthe ti
31、me of immersion as the starting time. Maintain thetemperature of the liquid bath between 98 and 102C. Observethe temperature to the nearest 0.1C at intervals during the test,and record the average temperature to the nearest 0.1C as thetemperature of the test. Make a continuous record of thepressures
32、 in the pressure vessel, or if an indicating pressuregage is used, take pressure readings at 15-min intervals or less.If, during the initial 30 min of the test, a leak develops (asindicated by a steady drop in pressure considerably in excess of14 kPa in 15 min) discard the test. Continue the test un
33、tilreaching a point preceded by a pressure drop of exactly 14 kPain 15 min and succeeded by a drop of not less than 14 kPa in15 min or until the induction period exceeds the productspecification. If no breakpoint is observed at the termination ofthe test, refer to Section 12 for reporting the result
34、.(WarningIf a boiling water bath is used and the test is madein a region where the atmospheric pressure is consistentlybelow normal (101.3 kPa), it is permissible to add a liquid withhigher boiling point, such as ethylene glycol, to the water inorder to maintain the operating temperature of the bath
35、 in theneighborhood of 100C. If a liquid other than water is used, besure the liquid is compatible with the seals in the pressurevessel.)10.3 Record the number of minutes from the time thepressure vessel is placed in the bath until the breakpoint hasbeen reached as the observed induction period at t
36、he tempera-ture of the test.10.4 Cool the pressure vessel to approximately room tem-perature within 30 min after removal from the bath, usingambient air or water # 35C, before releasing the pressureD525052slowly from the pressure vessel through the needle valve at arate not exceeding 345 kPa per min
37、ute. Wash the pressurevessel and sample container in preparation for the next test.11. Calculation11.1 The number of minutes from the time the pressurevessel is placed in the bath until the breakpoint has beenreached is the observed induction period at the temperature ofthe test.11.2 Method of Calcu
38、lationCalculate the induction periodat 100C from one of the following equations: When the testtemperature is above 100C:Induction period at 100C 5 IPt!1 1 0.101ta2 100! (1)When the test temperature is below 100C:Induction period at 100C, min 5 IPt!/1 1 0.101100 2 tb! (2)where:IPt= induction period,
39、min, at the temperature of the test,ta= test temperature when above 100C, C, andtb= test temperature when below 100C, C.12. Report12.1 Report the Induction period at 100C, calculated as in11.2 to the nearest 1 min.12.2 If the test was stopped prior to observing the pressuredrop required in 10.2, but
40、 after the product specification wasexceeded, then report the result as being greater than N min,where N is the product specification in min.12.3 If a slow oxidation of the sample is occurring ratherthan a breakpoint as defined in 10.2, then report the sample asa slow oxidizing fuel with the total t
41、ime for the test and theoverall pressure drop from the start of the test. A precision andbias statement has not been determined for this case.13. Precision and Bias13.1 The precision of the test method as determined bystatistical examination of interlaboratory test results is asfollows:13.1.1 Repeat
42、abilityThe difference between two test re-sults, obtained by the same operator with the same apparatusunder constant operating conditions on identical test material,would in the long run, in the normal and correct operation ofthe test method, exceed the following values only in one casein twenty: 5
43、%.13.1.2 ReproducibilityThe difference between two singleand independent results obtained by different operators work-ing in different laboratories on identical test material would, inthe long run, in the normal and correct operation of the testmethod, exceed the following values only in one case in
44、twenty: 10 %.13.2 BiasThere being no criteria for measuring bias inthese test-product combinations, no statement of bias can bemade.NOTE 4The precision values given above for induction period wereobtained using a boiling water bath only as the heat source. Therefore,these precision values are not ne
45、cessarily applicable to induction periodresults obtained using other heat sources.14. Keywords14.1 breakpoint; gasoline; induction period; oxidationstabilityANNEX(Mandatory Information)A1. APPARATUSA1.1 ApparatusA1.1.1 Pressure VesselThe pressure vessel shall be madeof corrosion-resistant steel with
46、 the inside dimensions of theportion that encloses the reacting gasoline-oxygen mixtureconforming substantially to those shown in Fig. A1.1. Fig.A1.1 is a composite drawing of specific pressure vessels andrelated apparatus for performing Test Method D 525 as madeby various manufacturers. As such, ra
47、nges of specific dimen-sions have been given and are not intended to be precise.Pressure vessels conforming to Test Method D 525/1980-1995as well as IP 40 are also suitable, but the specified burst-discshall be attached. Small variations in external dimensions arenot considered to significantly impa
48、ct the results of the test, butspecific studies to document potential effects, if any, have notbeen carried out. A minimum wall thickness of 5 mm in thepressure vessel is specified for safety reasons. (WarningPressure vessel assembly components obtained from differentsuppliers/manufacturers may not
49、be compatible.)A1.1.1.1 The interior surfaces of the pressure vessel andpressure vessel closure shall have a high polish such as asurface roughness of 0.20 to 0.40 micrometres, to facilitatecleaning and to prevent corrosion.A1.1.1.2 Other structural details, such as method of closure,(polygonal or knurled) gasket material, and outside dimensionsare optional provided the limitations listed in A1.1.1.3 andA1.1.1.4 are observed:NOTE A1.1Initial testing and periodic examination of the pressurevessel should be carried out to ensure its fi
