ASTM G74-2001 Standard Test Method for Ignition Sensitivity of Materials to Gaseous Fluid Impact《材料对气流冲击着火敏感度的标准测试方法》.pdf

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1、Designation: G 74 01Standard Test Method forIgnition Sensitivity of Materials to Gaseous Fluid Impact1This standard is issued under the fixed designation G 74; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revisi

2、on. A number in parentheses indicates the year of last reapproval. A superscriptepsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This method describes a technique to determine therelative sensitivity of materials to dynamic pressure impacts bygases such as

3、oxygen, air, or blends of gases containingoxygen.1.2 This method describes the test apparatus and test pro-cedures that may be employed in the evaluation of materials foruse in gases under dynamic pressure operating conditions up togage pressures of 10 000 psi (69 MPa) at ambient temperature.1.3 Thi

4、s method is primarily a test for ranking of materials.This method is not necessarily valid for determination of thesensitivity of the materials in an “as-used” configuration sincethe material sensitivity may be altered because of changes inmaterial configuration, usage, and environment. This methodc

5、an be employed to provide batch-to-batch acceptance data.Acceptability of any material may be based on its performanceat a particular test pressure, or test pressure may be varied todetermine the reaction threshold of a material, as specified bythe user.1.4 The criteria used for the acceptance, rete

6、st, and rejectionof materials for any given application shall be determined bythe user and are not fixed by this method.1.5 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 appro-pr

7、iate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specificprecautions see Section 7.2. Referenced Documents2.1 ASTM Standards:D 1193 Specification for Reagent Water2G 63 Guide for Evaluating Non-Metallic Materials for Oxy-gen Service3G 93 P

8、ractice for Cleaning Methods and Cleanliness Levelsfor Material and Equipment Used in Oxygen-EnrichedEnvironments3MNL36 Safe Use of Oxygen and Oxygen Systems: Guide-lines for Oxygen System Design, Materials Selection,Operations, Storage, and Transportation42.2 Military Standards:5MIL-D-16791-E Deter

9、gent, General Purpose (Liquid, Non-ionic)MIL-0-27210E, Amendment 1-Oxygen, Aviators Breath-ing, Liquid and Gas3. Summary of Method3.1 The gaseous impact test system is designed to exposematerial specimens or small components/elements to high-velocity (dynamic) gaseous impact environments. The basicc

10、onfiguration consists of a high-pressure accumulator, a high-speed pressurization (impact) valve, test system pressurizationlines, test chamber/fixture, test chamber purge and vent sys-tems, and a valve sequencer/control device. Fig. 1 is aschematic of a typical test system.3.2 The general procedure

11、 is to prepare the test specimen,record significant pretest data, and place the test specimen inthe test chamber. The test specimen is then subjected tosequential gaseous impacts by alternately opening and closingthe test chamber pressurization (impact) and vent valves. Thetest data obtained may inc

12、lude test chamber pressures andtemperatures, test chamber pressure rise times, pressurizationand vent valve actuation times, and sequence times. The testspecimen is then removed and examined for any significantchanges and evidence of reactions. Pertinent data are recorded.The test is repeated using

13、a fresh specimen for each impact testcycle until the desired user-selected criteria are met.4. Significance and Use4.1 This test evaluates the relative sensitivity of materials todynamic pressure impacts by various gaseous fluid media (mayinclude mixtures of gases).4.2 Any change or variations in te

14、st specimen configura-tions, thickness, preparation, and cleanliness may cause asignificant change in impact sensitivity/reaction.4.3 A reaction is indicated by an abrupt increase in testspecimen temperature or by obvious changes in odor, color, ormaterial appearance, or a combination thereof, as ob

15、served1This method is under the jurisdiction of ASTM Committee G4 on Compatibilityand Sensitivity of Materials in Oxygen Enriched Atmospheres and is the directresponsibility of Subcommittee G04.01 on Test Methods.Current edition approved Sept. 10, 2001. Published January 2002 Originallypublished as

16、G7482. Last previous edition G7482(1996)e1.2Annual Book of ASTM Standards, Vol 11.01.3Annual Book of ASTM Standards, Vol 14.04.4Available from ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428.5Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700Robbins Ave., Philadelph

17、ia, PA 19111-5094, Attn: NPODS.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.during post test examinations. Odor alone is not consideredpositive evidence that a reaction has occurred.4.4 Suggested criteria for test completion at a

18、given pressureare:4.4.1 Each specimen is subjected to five impacts.4.4.2 A material passes if no reactions occur in 20 succes-sive samples.4.4.3 A material fails if one reaction occurs in a maximumof 20 or fewer successive samples.4.5 Materials may be ranked by the maximum pressure(pressure threshol

19、d) at which they pass the test.4.6 Material acceptance may be on the basis of passing at aselected pressure.5. Apparatus5.1 A typical gaseous impact test system used for determin-ing the sensitivity of materials to gaseous impact (adiabaticcompression) is schematically depicted in Fig. 1. Details of

20、 thistypical test system are depicted in Figs. 2-5. The major testsystem components are described as follows:5.1.1 The accumulator provides gaseous test fluid storageand is precharged to the desired test pressure (potential energyhead). The capacity requirement is dependent on the testchamber and li

21、ne size and the number of impacts required pertest sequence. It is sized to limit static head loss to less than4 % of initial pressure during any test sequence.5.1.2 The test chamber shall be pressurized from the baseline pressure value (normally atmospheric ambient pressure) to95 % of test pressure

22、 in not less than 10 nor more than 50 ms.This range is not to be construed to be an acceptable variationin any one system, but is the pressure rise time range permittedamong different systems. The average pressure rise time of agiven system shall vary not more than 620 % at a given testpressure duri

23、ng the operational life of the system nor vary morethan 63 ms for a given test set of 20 impacts.5.1.3 The fluid lines between the accumulator and pressur-ization valve shall be sized to minimize flow losses and enablepressurization of test chamber in accordance with 5.1.2. Theselines shall contain

24、an isolation valve to provide a safety factorfor system operation. The isolation valve shall have a flowfactor at least equal to the pressurization (impact) valve.5.1.4 The test chamber vent valve shall be sized to allow thetest chamber pressure to decay to atmospheric pressure be-tween impacts.NOTE

25、 1The ability of a given gaseous impact test system to rankmaterials is based on two basic parameters: the test chamber pressuriza-tion rate and the accumulator pressure. There may be variations in the testchamber pressurization rate of different test systems at a given test(accumulator) pressure; h

26、owever, the test chamber pressurization rate of agiven test system shall be maintained within the limits specified in5.1.2-5.1.4. If these limits are maintained, a test system should be able torank materials. For example, a properly functioning test system shouldrank most batches of chloroprene rubb

27、ers below most batches of vi-nylidene fluoride hexafluoropropylene rubbers, which should rank belowmost batches of polytetrafluoroethylene polymers. This ranking cannot,however, be considered absolute due to material batch differences im-posed by contamination, differences in types and amounts of mo

28、ld releaseagents, differences in cures, etc.5.1.5 The inside diameter and the length of the pressuriza-tion line to the test chamber are critical. This section alsocontains a six-way cross for purge, vent, and instrumentationline connections. All line sections between the accumulator andthe test cha

29、mber shall be straight and smooth to minimize flowlosses. Dimensions of the lines and six-way cross for a typicaltest system are shown in Fig. 2.5.1.6 The gaseous impact test chamber subassembly isconfigured to hold and position the test specimen. It alsoEquipment List:A-K See Fig. Fig. 2L High-pres

30、sure Dwg 4-2219 (or equal)M High-pressure Catalog 60-22HF9 (or equal); orient as indicatedN Flodyne P/N 5A170 (or equal)P Teledyne Taber Model 2101 (or equal)Q Circle Seal P/N VC1009A (or equal)R Flodyne P/N 2A170 (or equal)FIG. 1 Gaseous Impact Test System SchematicG742contains a thermocouple to mo

31、nitor the test specimen tempera-ture. Other requisites include the ability to readily install andremove the test specimen. Details of a typical test chamber aredepicted in Figs. 3-5.5.2 The test specimen instrumentation and control require-ments include the following equipment:5.2.1 An automatic, re

32、mote valve sequencer which controlsthe opening and closing of the test chamber pressurization(impact) and vent valves during the test so that each impact/vent cycle will be completed in identical, prescribed timeperiods. It is preset to perform a prescribed number ofimpact/vent cycles.5.2.2 Test spe

33、cimen instrumentation and data requirementsinclude test fluid and test specimen temperatures, system staticpressure, and chamber pressures. Additional data may includepressurization (impact) rate or pressure rise time and vent valveactuation and timing, and should include response timesrequired of t

34、he instrumentation.6. Reagents and Materials6.1 Alkaline Cleaner, for test chambers, plumbing, andspecimen substrates, consisting of a solution of 15 g of sodiumhydroxide (NaOH), 15 g of trisodium phosphate (Na3PO4), and1 L of distilled or deionized water.6.2 Deionized or Distilled Water, conforming

35、 to Specifica-tion D 1193, Type IV.6.3 DetergentA noncorrosive, oxygen-compatible cleanerin the concentration used, conforming to MIL-D-16791E.6.4 Gaseous Oxygen, conforming to MIL-O-27210E,Amendment 1, Federal Specification BB-O-925, Type 1, oroxygen of 99.5 % purity. Oxygen of higher purity may be

36、 used,if desired.6.5 Gases used to dilute oxygen for testing in atmospheresother than pure oxygen should have a purity at least equal tothat specified for the oxygen component.7. Safety Precautions7.1 This may be a hazardous test. The test cell shall beconstructed of fire- and shrapnel-resistant mat

37、erials in a man-ner that shall provide protection from the effects of test systemcomponent rupture or fire which could result from test speci-men reaction or failure of a test system component.7.2 A pressure isolation valve shall be installed in the linebetween the accumulator and the pressurization

38、 (impact) valve(reference Fig. 1). This valve may be either manually orremotely operated and will provide for personnel protectionduring specimen loading and unloading operations.7.3 CautionApproved eye protection shall be worn in thetest area at all times. Other protective equipment such as glovesa

39、nd ear protection shall be required if the system vent isadjacent to the test system.7.4 No personnel shall be permitted in the test cell whenLine0ID OD Length Ain. mm in. mm in. mm in. mmA516 7.9916 14.3 4.50 114.3 0.375 9.5B516 7.9916 14.3 12.25 311.2 0.375 9.5C516 7.9916 14.3 11.96 303.8 0.375 9.

40、5D516 7.9916 14.3 10.95 278.1 0.375 9.5E516 7.9916 14.3 3.88 98.6 0.375 9.5F516 7.9916 14.3 4.00 101.6 0.375 9.5G116 1.614 6.4 2.43 61.7 0.125 3.2H332 2.414 6.4 5.30 134.6 0.125 3.2I332 2.414 6.4 2.25 57.2 0.125 3.2J516 7.9916 14.3 5.37 136.4 0.125 3.2K332 2.414 6.4 2.20 55.9 0.125 3.2FIG. 2 Test Ch

41、amber Purge, Pressurization, and Vent LinesG743remotely controlled valves are operated or when testing is inprogress.7.5 The housekeeping and maintenance characteristics ofthe test area shall be considered for both safety and cleanlinessaspects.7.6 Oxygen:Warning! Oxygen vigorously accelerates combu

42、stion.Keep oil and grease away. Do not use oil or grease onregulators, gages, or control equipment.Use only with equipment conditioned for oxygen service bycarefully cleaning to remove oil, grease, and other combus-tibles.Keep combustibles away from oxygen and eliminate ignitionsources.Keep surfaces

43、 clean to prevent ignition or explosion, or both,on contact with oxygen.Always use a pressure regulator. Release regulator tensionbefore opening cylinder valve.All equipment and containers used must be suitable andrecommended for oxygen service.Never attempt to transfer oxygen from cylinder in which

44、 it isreceived to any other cylinder. Do not mix gases in cylinders.Do not drop cylinder. Make sure cylinder is secured at alltimes.Keep cylinder valve closed when not in use.Stand away from outlet when opening cylinder valve.For technical use only. Do not use for inhalation purposes.Keep cylinder o

45、ut of sun and away from heat.Keep cylinder from corrosive environment.Do not use cylinder without label.Do not use dented or damaged cylinders.7.6.1 See Compressed Gas ASSOCIATION BOOKLETS G-4and G-4.1 for details of safe practice in the use of oxygen.8. Test Specimens8.1 Test the specimens in a thi

46、ckness of 0.060 6 0.005 in.(1.52 6 0.13 mm) (standard thickness), or in the end-usethickness if less than 0.055 in. (1.40 mm). If specimens aretested in a thickness other than 0.060 6 0.005 in., note thedeviation. The specimens shall be representative of the as-usedcondition. The as-used condition m

47、ay be either the newinstalled condition, or where preferable, the condition thatexists at any time in the service life.8.2 Maintain specimens clean at all times. Prepare andhandle the specimens with new, visibly clean, vinyl surgicalgloves or equivalent. Do not touch the materials or specimenswith b

48、are hands during or after the cleaning process.8.3 Typical preparation procedures for various materials areas follows:8.3.1 Sheet stock materials shall be in 0.060 6 0.005-in.(1.52 6 0.13-mm) thickness and prepared as316-in. (4.76-mm)-diameter disks.8.3.2 Apply coatings and paint in end-use thicknes

49、s ontoclean 0.060 6 0.005-in.-thick by316-in.-diameter (1.52 6 0.13by 4.76-mm), Type 316 stainless steel substrates. Cure appliedmaterial in accordance with the manufacturers recommenda-tions. Record cured coating thickness and application and cureprocedure for test reporting purposes.8.3.3 Prepare specimens of O-rings having a material diam-eter of316 in. (4.76 mm) or more in 0.060 6 0.005-in.thickness by316-in. (1.52 6 0.13 by 4.76-mm) diameter.Prepare O-rings having a material diameter of less than316 in.in316-in.-long segments.8.3.4 For tests of greas