1、Designation: D2863 17aStandard Test Method forMeasuring the Minimum Oxygen Concentration to SupportCandle-Like Combustion of Plastics (Oxygen Index)1This standard is issued under the fixed designation D2863; the number immediately following the designation indicates the year oforiginal adoption or,
2、in the case of revision, 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.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scop
3、e*1.1 This fire-test-response standard describes a procedurefor measuring the minimum concentration of oxygen, ex-pressed as percent volume, that will just support flamingcombustion in a flowing mixture of oxygen and nitrogen.1.2 This test method provides three testing procedures.Procedure A involve
4、s top surface ignition, Procedure B in-volves propagating ignition, and Procedure C is a shortprocedure involving the comparison with a specified minimumvalue of the oxygen index.1.3 Test specimens used for this test method are preparedinto one of six types of specimens (see Table 1).1.4 This test m
5、ethod provides for testing materials that arestructurally self-supporting in the form of vertical bars or sheetup to 10.5-mm thick. Such materials are solid, laminated orcellular materials characterized by an apparent density greaterthan 15 kg/m3.1.5 This test method also provides for testing flexib
6、le sheetor film materials, while supported vertically.1.6 This test method is also suitable, in some cases, forcellular materials having an apparent density of less than 15kg/m3.NOTE 1Although this test method has been found applicable fortesting some other materials, the precision of the test metho
7、d has not beendetermined for these materials, or for specimen geometries and testconditions outside those recommended herein.1.7 This test method measures and describes the response ofmaterials, products, or assemblies to heat and flame undercontrolled conditions, but does not by itself incorporate
8、allfactors required for fire hazard or fire risk assessment of thematerials, products, or assemblies under actual fire conditions.1.8 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.9 This standard does not purport to address
9、all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.Specific hazards statement are given in Secti
10、on 10.1.10 Fire testing is inherently hazardous. Adequate safe-guards for personnel and property shall be employed inconducting these tests.NOTE 2This test method and ISO 4589-2 are technically equivalentwhen using the gas measurement and control device described in 6.3.1,with direct oxygen concentr
11、ation measurement.1.11 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization T
12、echnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD1071 Test Methods for Volumetric Measurement of Gas-eous Fuel SamplesD1622 Test Method for Apparent Density of Rigid CellularPlasticsD4802 Specification for Poly(M
13、ethyl Methacrylate) AcrylicPlastic SheetD4968 Practice for Annual Review of Test Methods andSpecifications for PlasticsE176 Terminology of Fire StandardsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE456 Terminology Relating to Quality and StatisticsE691 Practice for Condu
14、cting an Interlaboratory Study toDetermine the Precision of a Test Method1This test method is under the jurisdiction ofASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.30 on Thermal Properties.Current edition approved Dec. 1, 2017. Published January 2018. Originally
15、approved in 1970. Last previous edition approved in 2017 as D2863 - 17. DOI:10.1520/D2863-17A.2For 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
16、 Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized p
17、rinciples on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1E2935 Practice for Conducting Equivalence Testing inLaboratory Applicat
18、ions2.2 ISO Standards:3ISO 4589-2 PlasticsDetermination of Flammability byOxygen IndexPart 2, Ambient TemperaturesISO 7823-1 Poly(Methylmethacrylate) SheetsTypes, Di-mensions and CharacteristicsPart 1Cast SheetsISO 13943 Fire SafetyVocabulary3. Terminology3.1 Definitions3.1.1 For definitions of term
19、s used in this test method referto the terminology contained in Terminology E176 and ISO13943. In case of conflict, the definitions given in TerminologyE176 shall prevail.3.2 Definitions of Terms Specific to This Standard:3.2.1 ignitionthe initiation of combustion.3.2.2 oxygen index (OI)the minimum
20、concentration ofoxygen, expressed as volume percent, in a mixture of oxygenand nitrogen that will just support flaming combustion of amaterial initially at 23 6 2C under the conditions of this testmethod.4. Summary of Test Method4.1 A small test specimen is supported vertically in amixture of oxygen
21、 and nitrogen flowing upwards through atransparent chimney. The upper end of the specimen is ignitedand the subsequent burning behavior of the specimen isobserved to compare the period for which burning continues,or the length of specimen burnt, with specified limits for eachburning. By testing a se
22、ries of specimens in different oxygenconcentrations, the minimum oxygen concentration is deter-mined.4.2 Three procedures are included in this test method. InProcedure A, a complete assessment of the oxygen index isconducted using top surface ignition. In Procedure B, acomplete assessment of the oxy
23、gen index is conducted usingpropagating ignition. Procedure C provides a comparison witha specified minimum value of oxygen index and can beconducted using top surface ignition or propagating ignition.5. Significance and Use5.1 This test method provides for the measuring of theminimum concentration
24、of oxygen in a flowing mixture ofoxygen and nitrogen that will just support flaming combustionof plastics. Correlation with burning characteristics underactual use conditions is not implied.5.2 In this test method, the specimens are subjected to oneor more specific sets of laboratory test conditions
25、. If differenttest conditions are substituted or the end-use conditions arechanged, it is not always possible by or from this test to predictchanges in the fire-test-response characteristics measured.Therefore, the results are valid only for the fire-test-exposureconditions described in this test me
26、thod.6. Apparatus6.1 Test Chimney. The test chimney consists of a heat-resistant glass tube of 75 to 100-mm inside diameter and 450to 500-mm height. The opening at the top of the chimney shallbe restricted to provide an outlet of 40 6 2-mm diameter, eitherby providing an overhead cap or by designing
27、 the glasschimney appropriately. The bottom of the chimney, or the baseto which the tube is attached, shall contain noncombustiblematerial to evenly mix and distribute the gas mixture enteringat this base. Glass beads 3 to 5 mm in diameter in a bed 80 to100-mm deep have been found suitable. The chim
28、ney shall bemounted securely on the base to prevent air leaks. Oneexample of a design is shown in Fig. 1.NOTE 3It is helpful to place a wire screen above the noncombustiblematerial to catch falling fragments and to aid in keeping the base of thecolumn clean.6.2 Specimen Holders6.2.1 Specimen Holder
29、for Self-Supporting SpecimensAny small holding device that will support the specimen at itsbase and hold it vertically in the center of the chimney is anacceptable specimen holder.Atypical arrangement (see Fig. 1)consists of a laboratory thermometer clamp inserted into theend of a glass tube held in
30、 place by glass beads or otherwisefirmly supported.6.2.2 Specimen Holder for Specimens of Flexible Sheet orFilm Materials that Require SupportA specimen holder forflexible film or sheet materials that require support shall be ableto support the specimen by both vertical edges in a frameequivalent to
31、 that illustrated by Fig. 2, with reference marks at20 and 100 mm below the top of the frame. The profile of theholder and its support shall be smooth to minimize induction ofturbulence in the rising flow of gas.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor,
32、New York, NY 10036, http:/www.ansi.org.TABLE 1 Test Specimen DimensionsTestSpecimenTypeADimensionsMaterial FormLength,mmWidth,mmThickness,mmI 80 to 150 10 0.5 4 0.25 for molding materialsII 80 to 150 10 0.5 10 0.5 for cellular materialsIIIB80 to 150 10 0.5 # 10.5 for sheet materialsIV 70 to 150 6.5
33、0.5 3 0.25 alternative size forself-supporting moldingor sheet materialsVB1405 520.5 #10.5 for flexible film or sheetVIB, C140 to 200 20 0.02 to0.10for thin film; limited to filmthat can be rolled by thewire specified in 6.7ATest specimens of Types I, II, III, and IV are suitable for materials that
34、areself-supporting at these dimensions. Test specimens of Form V and VI are suitablefor materials that require support during testing. Test specimens of Form VI aresuitable for film materials that can be rolled into a self-supporting specimen by theprocedure in 7.4.BCompare results obtained using Ty
35、pe III, V, and VI test specimens only to thoseobtained using specimens of the same form and thickness. It is assumed that theamount of variation in thickness for such materials will be controlled by otherstandards.CThe test specimen of Type VI is suitable for thin film that is self-supporting whenit
36、 is rolled (see 7.4). Dimensions in the table are of the specimen size from whichthe rolled form is made. If the film is very thin, it is possible that proper results willonly be obtained if two or more layers are combined in the preparation of the rollto obtain proper results.D2863 17a26.2.3 Thin F
37、ilm Rolling ToolIn order to prepare self-supporting specimens from thin films (see 7.4), use a 2 60.1-mm stainless steel rod with a 0.3 6 0.05-mm slit at oneend, equivalent to that illustrated in Fig. 3.The actual specimenholder shall be the one in 6.2.1.6.3 Gas Measurement and Control Devices. Gas
38、measure-ment and control devices shall be suitable for measuring theconcentration of oxygen in the gas mixture entering thechimney with an accuracy of 60.5 %, by volume, of the gasmixture and for adjusting the concentration of oxygen in themixture with a precision of 60.1 %, by volume, of the gasmix
39、ture, when the gas velocity through the chimney is 40 6 2mm/s at 23 6 2C.6.3.1 The system for gas measurement and control involvesneedle valves on individual and mixed gas supply lines, aparamagnetic oxygen analyzer that continuously samples themixed gas, and a flow meter to indicate when the gas fl
40、owthrough the chimney is within the required limits. See AnnexA4 for an alternate system for gas measurement.1. Burning Specimen 6. Glass Beads in a Bed 11. Pressure Gauge2. Clamp with Rod Support 7. Brass Base 12. Precision Pressure Regulator3. Igniter 8. Tee 13. Filter4. Wire Screen 9. Cut-Off Val
41、ve 14. Needle Valve5. Ring Stand 10. Orifice in Holder 15. RotameterFIG. 1 Typical Equipment LayoutD2863 17a36.3.2 The system used for gas measurement requires cali-bration after assembly to ensure that the compounded errors ofthe component parts do not exceed the requirements of 6.3.6.3.3 Means sha
42、ll be provided for checking or ensuring thatthe temperature of the gas mixture entering the chimney is 236 2C. If this involves an internal probe, its position andprofile shall be designed to minimize induction of turbulencewithin the chimney.6.4 Flame Igniter. The flame igniter shall comprise a tub
43、e,with an inside diameter of 2 6 1 mm, that can be inserted intothe chimney to apply the test flame.6.4.1 The fuel supply shall be adjusted so that the flameheight is 16 6 4 mm (measured from the bottom of the flameto the top of the flame) when the flame igniter tube is verticalwithin the chimney an
44、d the flame is burning within thechimney atmosphere (see Fig. 4).6.4.2 The flame fuel shall be one of the following: methane,or natural gas of at least 97 % purity, or propane of at least98 % purity. The flame fuel shall have no premixed air.6.5 Timing Device. A timing device shall be provided,which
45、 is capable of measuring periods up to 5 min with anaccuracy of 60.5 s.6.6 Fume Extraction System. Afume extraction system shallbe provided with sufficient ventilation or exhaust to removefumes or soot expelled from the chimney without disruptingthe gas-flow rate or temperatures in the chimney.NOTE
46、4If soot-generating materials are being tested, it is likely thatFIG. 2 Frame DesignFIG. 3 Rod with a SlitD2863 17a4the glass chimney, gas inlets, and inlet screen will require cleaningbetween tests to maintain good visibility and to function properly.6.7 Gas Supplies. The gas supplied to the test a
47、pparatusshall consist of pressurized sources of oxygen or nitrogen, orboth, not less than 98 % pure or clean dry air, or both,(containing 20.9 % oxygen), as appropriate.6.7.1 The gas mixture entering the chimney shall have amoisture content of 98 % pure, but as suchbottled gases are depressured to b
48、elow about 1 MPa, the moisture contentof the gas drawn off has been found to rise above 0.1 %.7. Test Specimens7.1 General:7.1.1 The specimens shall be die-punched, cut by handusing a razor blade or other sharp tool, or cut by an automaticmachine.Alternatively, specimens shall be prepared directly b
49、yinjection molding.7.1.2 Ensure that the surfaces of the specimens are clean andfree from flaws that could affect burning behavior, for example,peripheral molding flash or burrs from machining. The edgesof the specimens shall be smooth and free from fuzz or burrsof material left from machining or molding.7.1.3 Record the position and orientation of the test speci-mens with respect to any asymmetry in the sample material(see Note 6).NOTE 6Oxygen index results are likely to be significantly affected bydifferences in burning beh
