1、Designation: G 124 95 (Reapproved 2003)Standard Test Method forDetermining the Combustion Behavior of Metallic Materialsin Oxygen-Enriched Atmospheres1This standard is issued under the fixed designation G 124; 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers a test apparatus and techniqueto determine the minimum
3、 test gas pressure that supportsself-sustained combustion (the threshold pressure) and theaverage regression rate (apparent burn rate) of a standardizedsample of a metallic material that has been ignited using astrong promoter.1.2 The data obtained from this test method are dependenton the precise t
4、est sample configuration and provide a basis forcomparing the combustion behavior of materials. No criteriaare implied for relating these data to the suitability of amaterials use in any actual system. The application of dataobtained from this test method is discussed in Guides G 88 andG 94.1.3 Requ
5、irements for an apparatus suitable for this testmethod are given, as well as an example of such an apparatus.The example, however, is not required to be used.1.4 This test method is for gaseous oxygen or any mixtureof oxygen with diluents that will support combustion, at anypressure within the capab
6、ilities of the apparatus.1.5 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.6 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
7、standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific hazardsstatements are given in Section 9.2. Referenced Documents2.1 ASTM Standards:G 88 Guide for Designing Systems for Oxygen Service2G 93 Practice for Cl
8、eaning Methods for Material andEquipment Used in Oxygen-Enriched Environments2G 94 Guide for Evaluating Metals for Oxygen Service22.2 Federal Specification:BB-0-925 Oxygen, Technical, Gas and Liquid32.3 Military Standard:MIL-0-27210E Amendment 1Oxygen, Aviators Breath-ing, Liquid and Gas33. Terminol
9、ogy3.1 Definitions of Terms Specific to This Standard:3.1.1 average regression rate (apparent burn rate)theaverage rate at which the burning/solid-metal interface ad-vances along the test sample length.3.1.2 ignitera material to ignite the promoter that canburn under an electrical influence, such as
10、 a small-diameterwire.3.1.3 promotera material that can add supplemental heatand increase the temperature to start combustion of the materialbeing tested.3.1.4 self-sustained combustioncombustion that con-sumes a sample to the point at which the sample holder affectsfurther combustion (assuming suff
11、icient oxygen).3.1.5 threshold pressurethe minimum gas pressure (at aspecified oxygen concentration and ambient temperature) thatsupports self-sustained combustion of the entire standardsample.4. Summary of Test Method4.1 A small rod of the material is suspended in a chamberfilled with pressurized t
12、est gas. The chamber contains sufficientoxygen so that not more than 10 % of the oxygen will beconsumed when the material combusts completely. A promoter(typically aluminum or magnesium) applied to the bottom ofthe rod starts combustion of the material. The test pressure is1This test method is under
13、 the jurisdiction of ASTM Committee G4 onCompatibility and Sensitivity of Material in Oxygen Enriched Atmospheres and isthe direct responsibility of Subcommittee G04.01 on Test Methods.Current edition approved Feb. 15, 1995. Published August 1995. Originallypublished as G 124 94. Last previous editi
14、on G 124 94.2Annual Book of ASTM Standards, Vol 14.02.3Available from Standardization Documents Order Desk, Bldg 4 Section D, 700Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.TABLE 1 Example Data Set for Type 316 Stainless SteelAMaterial Pressure, MPaNumber of SamplesPartial Burn Complete B
15、urnUNS 31600 1.75 10 03.45 8 26.90 0 10AThese data were produced at NASA White Sands Test Facility, New Mexico,880041Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.reduced and another rod is tested if combustion of the entirerod occu
16、rs. This continues until self-sustained combustion ofthe rod does not occur for at least five tests at one pressure. Thelowest pressure at which self-sustained combustion occurred isthe threshold pressure for the material, and the differencebetween it and the highest pressure level that produced onl
17、yincomplete combustion is the margin of potential error. Astuteinitial estimates of the threshold can reduce the amount oftesting necessary to demonstrate the threshold to within therequired uncertainty.5. Significance and Use5.1 This test method will allow comparisons of the combus-tion characteris
18、tics of various metallic materials. The combus-tion characteristics that can be evaluated include (1) thresholdpressure and (2) average regression rate (apparent burn rate) ofthe sample.6. Interferences6.1 Any internal materials that may bake out or vaporizeduring the combustion process at test temp
19、erature/pressuremay interfere with the chemistry of the fire propagation.6.2 The specific atmosphere in the test chamber can have asevere effect. Therefore, alien air, argon, nitrogen, carbondioxide, moisture, and others can be important interferinggases.6.3 The test is conducted under stagnant cond
20、itions. Aflowing system or one that facilitates buoyant convectivecurrents may be a significantly more severe climate.6.4 The specific temperature of the test sample prior toignition can have an important effect.NOTE 1The promoters discussed in this test method have producedfavorable results over a
21、wide range of metal test specimens with thedegree of precision sought to date. As the threshold is approached or wheninteraction between promoter and metal occur promoter can thwart theignition process. Hence the prospect that future work may refine thepromoter and enable the measurement of lower th
22、resholds than aremeasurable today cannot be ruled out.7. Apparatus7.1 A schematic of a typical system is shown in Fig. 1.Other designs may also be used, if they fulfill the requirementsbelow.7.2 Test ChamberA cross-section of a typical stainlesssteel test chamber is shown in Fig. 2. No more than 10
23、% of theavailable oxygen should be consumed during a test. AppendixX1 provides criteria for establishing the lowest test pressuresthat meet this criterion for various vessel volumes. If thechamber cannot be made sufficiently large, an accumulator canbe attached that contains more test gas if the cha
24、mber cannot bemade sufficiently large; however, this is not as severe a testenvironment as in the larger vessel. The test chamber shall notcontribute any chemical interference to testing.NOTE 2The addition of an accumulator can act as a snubber tosuppress pressure rises that occur due to temperature
25、 rises and pressuredrops that result from oxygen consumption, but it will have a muchsmaller effect in preventing local buildup of diluents in the oxygen. Eachof these influences will exhibit a progressively greater effect and conse-quence in smaller vessels.NOTE 3The significance of ensuring an ade
26、quate oxygen inventory isto avoid the observation of apparently negative test results at conditionsthat are above the threshold but for which extinguishment may, nonethe-less, occur due to depletion of oxygen, consequential reduction ofpressure, or concentration of diluents. However, in any test in
27、whichcomplete combustion of the specimen occurs, the result is valid, regardlessof whether the test conditions met the minimum recommended require-ment for oxygen inventory.7.3 Sample holder, capable of securing the sample at the topand supporting it in a vertical position. There shall be sufficient
28、FIG. 1 Schematic of Typical SystemFIG. 2 Typical Stainless Steel Test Chamber Cross-SectionG 124 95 (2003)2space beneath the sample for the igniter and any drops of liquidmaterial that may fall during the test.7.4 Thermocouple, used to measure gas temperature in thechamber.7.5 Pressure Transducer, u
29、sed to measure gas pressure inthe chamber, accurate to within 6 1 % of reading.7.6 Liner and Base PlateA burn-resistant (for example,copper) liner and base plate in the test chamber serve as aninternal shield to protect the components from combustionproducts, molten slag, and so forth.7.7 Sight Glas
30、s, capable of withstanding the maximum testpressure anticipated. If video or film recording of the burningevent contained in the test chamber is desired, the sight glassshall transmit compatible light.7.8 Igniter Power Supply, electrically isolated and capableof providing adequate current to initiat
31、e the igniter wire withina few seconds of the application of power.7.9 Test Cell, (a room to house the test chamber), con-structed of noncombustible material (such as concrete or metal)with sufficient strength to provide protection from explosion orfire hazards. A continuous ventilation system shall
32、 circulatefresh air in the test cell. The cell shall provide a facility that canbe maintained at a high level of good housekeeping. The testcell shall be cleaned periodically to avoid contamination of thesample and equipment.7.10 Piping System, which purges, pressurizes, and ventsthe test chamber. T
33、he piping system shall be designed to permitremote test chamber purge, pressurization, and venting withoutunsafe exposure of personnel. The chamber shall be purged andpressurized through one line and vented through a separate lineto minimize the chances of contaminant migrating into thepressurizatio
34、n line, which might influence subsequent tests. Atypical piping system for this test is shown in Fig. 1.7.11 Control Area, which will isolate test personnel from thetest cell during tests. This control area shall be provided withthe necessary control and instrumentation features to performtest chamb
35、er purge, pressurization and venting operations, andmonitoring of the test chamber instrumentation during the test.7.12 Data Acquisition System (Optional), capable of record-ing, storing, and accessing the pressure and temperature data ata rate of ten samples/s (minimum). It shall also include a vid
36、eorecording device that displays the “real-time” burn phenom-enon. The video recording can be used for regression ratedetermination.8. Reagents and Materials8.1 Gaseous OxygenOxygen purity equal to or greaterthan that of practical systems is preferred, especially whentesting alloys containing alumin
37、um, magnesium, zirconium,etc. (that is, metals believed to burn at least in part in the vaporphase). An analysis of the test oxidant is required. The use ofoxygen greater than 99.5 % pure may affect the test resultssignificantly (1),4and its use shall be noted on the data sheet.NOTE 4Some applicatio
38、ns involve the use of oxygen mixed withother gases, and data in the literature (1, 2) indicate that the rankings ofmaterials can be different depending on the amount and kind of diluentspresent. Although the basic apparatus and principle of this test are validwhen used with oxygen mixed with other g
39、ases, alterations to the testmethod may be necessary. At present, these alterations have not beenstudied sufficiently for inclusion in this test method.8.2 PromoterThe promoter shall consist of a sufficientquantity of material to ignite the test specimens. Some ex-amples of promoter material are alu
40、minum and magnesium (3).No promoter may be necessary at all at times; the igniter wireitself may provide sufficient energy to ignite the sample.Nonmetallic promoters may be used; however, the combustionproducts of such promoters might contaminate the test media.NOTE 5In selecting the promoter materi
41、al, the possibility of achemical reaction between the test material and the promoter should beconsidered. Also, for certain metals, the chemical energy released from thecombustion of promoter might be insufficient to ignite the metal. Otherignition sources, for example, electrical or laser, may be u
42、sed in suchcases.8.3 Igniter WireThe igniter wire shall be made of amaterial capable of igniting the promoter. Some examples ofthe igniter wire material are nickel/chromium or aluminum/palladium.59. Hazards9.1 High-Pressure Oxygen SystemWarning: There arehazards involving the use of a high-pressure
43、oxygen system.The following guidelines will reduce the dangers:9.1.1 Personnel should be isolated from the test systemwhen it is pressurized. Preferably, personnel should be shieldedby both physical protection (for example, the test cell) anddistance.9.1.2 The test system itself should be isolated t
44、o preventdanger to people not involved in the test.9.1.3 The test system should incorporate equipment able tohandle the maximum operating pressure safely, including anappropriate safety-factor.9.1.4 The system should be kept clean to prevent uninten-tional ignition.9.1.5 The test system should be do
45、uble-isolated from thetest gas supply system.9.1.6 Remote readout devices should be provided so per-sonnel do not have to approach the test system to obtainoperating data.9.2 OxygenWarning: Oxygen enrichment acceleratescombustion vigorously. Care should be taken at all times whenworking with oxygen.
46、 CGA Pamphlets G-4.0 (4) and G-4.1 (5)and Practice G 93 provide further details.9.3 Metal OxidesWarning: Toxic metal and oxide dustsmay be produced when using this test method. These dusts areoften toxic to breathe or touch; safety procedures appropriate tothe hazard must therefore be followed.9.4 V
47、essel FailuresWarning: The vessel described in thisexperiment has contained the combustion of ferrous, alumi-num, and copper alloys successfully. Molten metal slags4The boldface numbers in parentheses refer to the list of references at the end ofthis test method.5The trade name for aluminum-palladiu
48、m wire is Pyrofuze. It is a registeredtrademark of the Pyrofuze Corp., 121 S. Columbus Ave., Mt. Vernon, NY 10553,and is available from them.G 124 95 (2003)3produced in these tests can be very destructive, and as pressureor oxygen purity increases, the intensity of the combustionincreases, so the po
49、ssibility of a burn-through or failure of thevessel or associated piping cannot be ruled out.10. Preparation of Test Samples and Promoters10.1 Preparation of SamplesThe samples shall be pre-pared as cylindrical rods, 3.2-mm diameter and 150-mm long(65 %), as shown in Fig. 3. The portion of the sample includedin the sample mount and the promoter shall be excluded fromthis measurement. Samples shall be prepared exclusively forthis test.10.2 Preparation of PromotersThe promoter shall consistof a sufficient quantity of a material to ignite the samplepositively.1
