1、Designation: D2863 10Standard 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, i
2、n 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. Scope1.1 T
3、his 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 top s
4、urface 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 method p
5、rovides 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 shee
6、tor 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 has n
7、ot 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 allfact
8、ors 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 all of
9、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. Specific hazardsstatement are given in Section 10.1.10 Fire testing
10、 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 concentration measurement.2. Re
11、ferenced 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(Methyl Methacrylate)AcrylicPlastic SheetE176 Ter
12、minology of Fire StandardsE691 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(Methylmethacrylate) SheetsTypes, Di-mensions and Cha
13、racteristicsPart 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 E176 andISO 13943. In case of conflict, the definitions given in Termi-nology E176 shall prevail.1This tes
14、t 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, 2010. Published August 2010. Originallyapproved in 1970. Last previous edition approved in 2009 as D2863 - 09. DOI:10.1520
15、/D2863-10.2For 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 Summary page onthe ASTM website.3Available from American National Standards Institu
16、te (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2 Definitions: Definitions Specific to This Standard:3.2.1 ignitionthe initiation of combustion.3.2.2 oxyge
17、n index (OI)the minimum concentration ofoxygen determined by the method in 12.1, expressed as volumepercent, in a mixture of oxygen and nitrogen that will justsupport flaming combustion of a material initially at 23 6 2Cunder the conditions of this test method.3.3 Symbols Specific To This Test Metho
18、d: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 six responses in the NTseries.3.3.4 Oneither the period or extent of burning exceeds therelevant limit
19、 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=NL+ 5).3.3.8 s*standard deviation of the oxygen concentration.3.3.9 dinterval between oxygen concentra
20、tion 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 vertically in amixture of oxygen and nitrogen flowing upwards through atransparent chimney. The upper en
21、d 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 series of specimens in different oxygenconcentrations, the minimum oxygen
22、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 oxygen index is conducted usingpropagating ignition. Procedure C provides a
23、 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 of oxygen in a flowing mixture ofoxygen and nitrogen that will just supp
24、ort 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. If differenttest conditions are substituted or the end-use conditions
25、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 method.6. Apparatus6.1 Test Chimney. The test chimney consists of a heat-r
26、esistant 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 the glasschimney appropriately. The bottom of the chimney, or the baset
27、o 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 chimney shall bemounted securely on the base to prevent air leaks. Oneexampl
28、e of a design is shown in Fig. 1.NOTE 3It is helpful to place a wire screen above the noncombustibleTABLE 1 Test Specimen DimensionsTestSpecimenTypeADimensionsMaterial FormLength,mmWidth,mmThickness,mmI 80 to 150 10 6 0.5 4 6 0.25 for molding materialsII 80 to 150 10 6 0.5 10 6 0.5 for cellular mate
29、rialsIIIB80 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 0.02 to0.10for thin film; limited to filmthat can be rolled by thewire specified in 6.
30、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 specimens of Form VI aresuitable for film materials that can be rolled into a self-
31、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 variation in thickness for such materials will be controlled byother standards.CThe Type
32、 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 table are of the specimen size fromwhich the rolled form is made. If the film is very
33、 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 (See Table 1)Ignition ProcedureAlternative CriteriaPeriod ofBurningAfterIgnition(s
34、)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 mm below theupper referencemark (on the frame)AThese criteria do not necessarily pr
35、oduce 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 specimen, including burning drips descending the vertical faces, passes thelevel indica
36、ted in the column.D2863 102material to catch falling fragments and to aid in keeping the base of thecolumn clean.6.2 Specimen 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 chimn
37、ey is anacceptable 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 supported.6.2.2 Specimen Holder for Specimens of Flexible Sheet orFilm Materials that Require SupportA s
38、pecimen 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 marks at20 and 100 mm below the top of the frame. The profile of theholder and its support shall be s
39、mooth 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 rod with a 0.3 6 0.05-mm slit at oneend, equivalent to that illustrated in Fig. 3.The actual specime
40、nholder 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 thechimney with an accuracy of 60.5 %, by volume, of the gasmixture and for adjusting the concentrati
41、on 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 controlinvolves needle valves on individual and mixed gas supplylines, a paramagnetic oxygen analyzer
42、 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 use direct oxygen concentration measurements, buthas proved satisfactory. It includes the following:
43、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 requires calibration after assembly toensure that the compounded errors of the component parts donot
44、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 position andprofile shall be designed to minimize induction of turbulencewithin the chimney.6.4 Flame I
45、gniter. 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 of atleast 97 % purity, without premixed air. The fuel supply shallbe adjusted so that the flame proj
46、ects 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 provided, whichis capable of measuring periods up to 5 min with an accuracyof 60.5 s.6.6 Fume Extraction Sy
47、stem.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 4If soot-generating materials are being tested, it is likely thatthe glass chimney, gas inlets
48、, 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 of oxygen or nitrogen, orboth, not less than 98 % pure or clean dry air, or both,(containing 20.9 %
49、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 below about 1 MPa, the moisture contentof the gas drawn off has been found to rise above 0.1 %.7. Test Specimens7.1 General.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 Valve 14. Needle Valve5. Ring Stand 10. Orifice in Holder 15. RotameterFIG. 1 Typical Equipment
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