1、Designation: D 2863 08Standard Test Method forMeasuring the Minimum Oxygen Concentration to SupportCandle-Like Combustion of Plastics (Oxygen Index)1This standard is issued under the fixed designation D 2863; 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 Department of Defense.1. Scope*1.
3、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 involves to
4、p 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 metho
5、d 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 flexible s
6、heetor 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 method ha
7、s 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 allf
8、actors required for fire hazard or fire risk assessment of thematerials, products, or assemblies under actual fire conditions.1.8 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 ap
9、pro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific hazardsstatement are given in Section 10.NOTE 2This test method and ISO 4589-2 are technically equivalentwhen using the gas measurement and control device described in 6.3.1,with
10、direct oxygen concentration measurement.2. Referenced Documents2.1 ASTM Standards:2D 618 Practice for Conditioning Plastics for TestingD 1071 Test Methods for Volumetric Measurement of Gas-eous Fuel SamplesD 1622 Test Method forApparent Density of Rigid CellularPlasticsD 4802 Specification for Poly(
11、Methyl Methacrylate)Acrylic Plastic SheetE 176 Terminology of Fire StandardsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Standards:3ISO 4589-2 PlasticsDetermination of Flammability byOxygen IndexPart 2, Ambient TemperaturesISO 7823-1 Poly(M
12、ethylmethacrylate) SheetsTypes, Di-mensions and CharacteristicsPart 1Cast SheetsISO 13943 Fire SafetyVocabulary3. Terminology3.1 Definitions3.1.1 For definitions of terms used in this test method referto the terminology contained in Terminology E 176 andISO 13943. In case of conflict, the definition
13、s given in Termi-nology E 176 shall prevail.3.2 Definitions: Definitions Specific to This Standard:3.2.1 ignitionthe initiation of combustion.3.2.2 oxygen index (OI)the minimum concentration ofoxygen determined by the method in 12.1, expressed as volumepercent, in a mixture of oxygen and nitrogen th
14、at will justsupport flaming combustion of a material initially at 23 6 2Cunder the conditions of this test method.1This 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 Aug. 1,
15、 2008. Published September 2008. Originallyapproved in 1970. Last previous edition approved in 2006 as D 2863 - 06a.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
16、the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive
17、, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.3 Symbols Specific To This Test Method:3.3.1 Cooxygen concentration in percent volume.3.3.2 CFfinal value of oxygen concentration in percentvolume.3.3.3 Cieach of the oxygen concentration percentagesused during measurement of the last
18、six responses in the NTseries.3.3.4 Oneither the period or extent of burning exceeds therelevant limit specified in Table 2.3.3.5 Xthe period or extent of burning exceeds the rel-evant limit specified in Table 2.3.3.6 NLseries of “X” or “O” results.3.3.7 NTseries of “X” or “O” results plus five (NT=
19、NL+ 5).3.3.8 s*standard deviation of the oxygen concentration.3.3.9 dinterval between oxygen concentration levels inpercent volume.3.3.10 ka factor to be determined from Table 3.3.3.11 nnumber of measurements of oxygen concentra-tion.4. Summary of Test Method4.1 A small test specimen is supported ve
20、rtically in amixture of oxygen 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 fo
21、r eachburning. By testing a series 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, a
22、complete assessment of the oxygen 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 measurin
23、g of theminimum concentration 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
24、 of laboratory test conditions. 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-exposurecondit
25、ions described in this test method.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 a
26、n overhead cap or by designing 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
27、 been found suitable. The chimney 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
28、 Holders6.2.1 Specimen Holder 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 anTABLE 1 Test Specimen DimensionsTestSpecimenTypeADimensionsMaterial FormLength,mmWidth,mmThickness,mmI 80 to 150 10 6
29、 0.5 4 6 0.25 for molding materialsII 80 to 150 10 6 0.5 10 6 0.5 for cellular materialsIIIB80 to 150 10 6 0.5 # 10.5 for sheet materialsIVC70 to 150 6.5 6 0.5 3 6 0.25 alternative size forself-supporting moldingor sheet materialsVB140 6 5526 0.5 #10.5 for flexible film or sheetVIBD140 to 200 20 0.0
30、2 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 areself-supporting at these dimensions. Test specimens of Form V and VI are suitablefor materials that require support during testing. Test
31、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 Type III, V, and VI test specimens only tothose obtained using specimens of the same form and thickness. It is assumedthat the amount of varia
32、tion in thickness for such materials will be controlled byother standards.CThe Type IV (ASTM) specimen will eventually be discontinued in favor of theType 1 (ISO) specimen.DThe test specimen of Type VI is suitable for thin film that is self-supportingwhen it is rolled (see 7.4). Dimensions in the ta
33、ble are of the specimen size fromwhich the rolled form is made. If the film is very thin, it is possible that properresults will only be obtained if two or more layers are combined in the preparationof the roll to obtain proper results.TABLE 2 Criteria for Oxygen Index MeasurementsATest SpecimenType
34、 (See Table 1)Ignition ProcedureAlternative CriteriaPeriod ofBurningAfterIgnition(s)Extent of BurningBI, II, III, IV, and VI A(top surface ignition)180 50 mm below the topof the specimenI, II, III, IV, and VI B(propagating ignition)180 50 mm below theupper referencemarkV propagating ignition 180 80
35、mm below theupper referencemark (on the frame)AThese criteria do not necessarily produce equivalent oxygen index results forspecimens of differing shape or tested using different ignition conditions orprocedures.BThe extent of burning is exceeded when any part of the visibly burning portionof a spec
36、imen, including burning drips descending the vertical faces, passes thelevel indicated in the column.D2863082acceptable specimen holder.Atypical arrangement (see Fig. 1)consists of a laboratory thermometer clamp inserted into theend of a glass tube held in place by glass beads or otherwisefirmly sup
37、ported.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 that illustrated by Fig. 2, with reference
38、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.6.2.3 Thin Film Rolling ToolIn order to prepare self-supporting specimens from thin films (see 7.4), use a 2 60.1-mm stainless steel
39、 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 measure-ment and control devices shall be suitable for measuring theconcentration of oxygen in the gas mixture entering
40、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 gasmixture, when the gas velocity through the chimney is 40 6 2mm/s at 23 6 2C.6.3.1 A typical system for gas measurement and
41、controlinvolves needle valves on individual and mixed gas supplylines, a paramagnetic oxygen analyzer that continuouslysamples the mixed gas, and a flowmeter to indicate when thegas flow through the chimney is within the required limits.6.3.2 An alternative system of measurement and controldoes not
42、use direct oxygen concentration measurements, buthas proved satisfactory. It includes the following: calibratedorifices, gas pressure regulators, and pressure gauges on theindividual gas supply lines and needle valves and calibratedflowmeters on the individual gas supply lines.6.3.3 Any system used
43、requires calibration after assembly toensure that the compounded errors of the component parts donot exceed the requirements of 6.3.6.3.4 Means shall 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 po
44、sition andprofile shall be designed to minimize induction of turbulencewithin the chimney.6.4 Flame Igniter. The flame igniter shall comprise a tube,with an inside diameter of 2 6 1 mm, that can be inserted intothe chimney to apply the test flame.6.4.1 The flame fuel shall be methane or natural gas
45、of atleast 97 % purity, without premixed air. The fuel supply shallbe adjusted so that the flame projects 16 6 4 mm verticallydownwards from the outlet when the tube is vertical within thechimney and the flame is burning within the chimney atmo-sphere.6.5 Timing Device.Atiming device shall be provid
46、ed, whichis capable of measuring periods up to 5 min with an accuracyof 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 chimne
47、y.NOTE 4If soot-generating materials are being tested, it is likely thatthe 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 apparatusshall consist of pressurized sources
48、 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 suchTABLE 3 Determination of k12 4 5 6Responses for the Last FiveMeasurementsValue
49、s of k for which the first NLdeterminations are:Responses for the Last FiveMeasurementsA(a) O OO OOO OOOOXOOOO 0.55 0.55 0.55 0.55 OXXXXXOOOX 1.25 1.25 1.25 1.25 OXXXOXOOXO 0.37 0.38 0.38 0.38 OXXOXXOOXX 0.17 0.14 0.14 0.14 OXXOOXOXOO 0.02 0.04 0.04 0.04 OXOXXXOXOX 0.50 0.46 0.45 0.45 OXOXOXOXXO 1.17 1.24 1.25 1.25 OXOOXXOXXX 0.61 0.73 0.76 0.76 OXOOOXXOOO 0.30 0.27 0.26 0.26 OOXXXXXOOX 0.83 0.76 0.75 0.75 OOXXOXXOXO 0.83 0.94 0.95 0.95 OOXOXXXOXX 0.30 0.46 0.50 0.50 OOXOOXXXOO 0.50 0.65 0.68 0.68 OOOXXXXXOX 0.04 0.19 0.24 0.25 OOO
