1、Designation: G 74 08Standard 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 () 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 o
3、xygen, 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 This
4、 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. Acceptability
5、of any material may be based on its performance at a particulartest pressure, or test pressure may be varied to determine thereaction threshold of a material, as specified by the user.1.4 The criteria used for the acceptance, retest, and rejectionof materials for any given application shall be deter
6、mined 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-priate safety and health practices and determine the applica-bility of r
7、egulatory limitations prior to use. For specificprecautions see Section 7.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterG93 Practice for Cleaning Methods and Cleanliness Levelsfor Material and Equipment Used in Oxygen-EnrichedEnvironmentsMNL36 Safe Use of Oxygen an
8、d Oxygen Systems: Guide-lines for Oxygen System Design, Materials Selection,Operations, Storage, and Transportation32.2 Military Standards:4MIL-D-16791-E Detergent, General Purpose (Liquid, Non-ionic)MIL-0-27210E, Amendment 1-Oxygen, Aviators Breath-ing, Liquid and Gas3. Summary of Method3.1 The gas
9、eous impact test system is designed to exposematerial specimens or small components/elements to high-velocity (dynamic) gaseous impact environments. The basicconfiguration consists of a high-pressure accumulator, a high-speed pressurization (impact) valve, test system pressurizationlines, test chamb
10、er/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 is to prepare the test specimen,record significant pretest data, and place the test specimen inthe test chamber. The test specimen is then s
11、ubjected tosequential gaseous impacts by alternately opening and closingthe test chamber pressurization (impact) and vent valves. Thetest data obtained may include test chamber pressures andtemperatures, test chamber pressure rise times, pressurizationand vent valve actuation times, and sequence tim
12、es. The testspecimen is then removed and examined for any significantchanges and evidence of reactions. Pertinent data are recorded.The test is repeated using a fresh specimen for each impact testcycle until the desired user-selected criteria are met.4. Significance and Use4.1 This test evaluates th
13、e relative sensitivity of materials todynamic pressure impacts by various gaseous fluid media (mayinclude mixtures of gases).4.2 Any change or variations in test specimen configura-tions, thickness, preparation, and cleanliness may cause asignificant change in impact sensitivity/reaction.4.3 A react
14、ion is indicated by an abrupt increase in testspecimen temperature or by obvious changes in odor, color, ormaterial appearance, or a combination thereof, as observedduring post test examinations. Odor alone is not consideredpositive evidence that a reaction has occurred.1This method is under the jur
15、isdiction of ASTM Committee G04 on Compat-ibility and Sensitivity of Materials in Oxygen Enriched Atmospheres and is thedirect responsibility of Subcommittee G04.01 on Test Methods.Current edition approved Sept. 1, 2008. Published October 2008 . Originallyapproved in 1982. Last previous edition appr
16、oved in 2001 as G 7401.2For 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 fromASTM, 100 Barr Harbor D
17、rive, West Conshohocken, PA19428.4Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.4 Suggested criteri
18、a for test completion at a 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
19、 pressure(pressure threshold) 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 dep
20、icted in Fig. 1. Details of 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 dependen
21、t on the testchamber and line 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 pressu
22、re) to95 % of test pressure 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 % a
23、t a given testpressure during 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
24、. Theselines shall contain 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 pre
25、ssure be-tween impacts.NOTE 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 te
26、st(accumulator) pressure; however, 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
27、batches of chloroprene rubbers below most batches of vi-nylidene fluoride hexafluoropropylene rubbers, which should rank belowmost batches of polytetrafluoroethylene polymers.5.1.5 The inside diameter and the length of the pressuriza-tion line to the test chamber are critical. This section alsoconta
28、ins a six-way cross for purge, vent, and instrumentationline connections.All line sections between the accumulator andthe test chamber 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
29、test chamber subassembly isconfigured to hold and position the test specimen. It alsocontains a thermocouple to monitor 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.Equi
30、pment List:A-K See Fig. Fig. 2L High-pressure 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 S
31、chematicG740825.2 The test specimen instrumentation and control require-ments include the following equipment:5.2.1 An automatic, remote 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 wil
32、l be completed in identical, prescribed timeperiods. It is preset to perform a prescribed number ofimpact/vent cycles.5.2.2 Test specimen instrumentation and data requirementsinclude test fluid and test specimen temperatures, system staticpressure, and chamber pressures. Additional data may includep
33、ressurization (impact) rate or pressure rise time and vent valveactuation and timing, and should include response timesrequired of the instrumentation.6. Reagents and Materials6.1 Alkaline Cleaner, for test chambers, plumbing, andspecimen substrates, consisting of a solution of 15 g of sodiumhydroxi
34、de (NaOH), 15 g of trisodium phosphate (Na3PO4), and1 L of distilled or deionized water.6.2 Deionized or Distilled Water, conforming 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, confo
35、rming to MIL-O-27210E,Amendment 1, Federal Specification BB-O-925, Type 1, oroxygen of 99.5 % purity. Oxygen of higher purity may be 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 co
36、mponent.7. Safety Precautions7.1 This may be a hazardous test. The test cell shall beconstructed of fire- and shrapnel-resistant materials 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
37、 a test system component.7.2 A pressure isolation valve shall be installed in the linebetween the accumulator and the pressurization (impact) valve(reference Fig. 1). This valve may be either manually orremotely operated and will provide for personnel protectionduring specimen loading and unloading
38、operations.7.3 CautionApproved eye protection shall be worn in thetest area at all times. Other protective equipment such as glovesand ear protection shall be required if the system vent isadjacent to the test system.Line0ID OD Length Ain. mm in. mm in. mm in. mmA516 7.9916 14.3 4.50 114.3 0.375 9.5
39、B516 7.9916 14.3 12.25 311.2 0.375 9.5C516 7.9916 14.3 11.96 303.8 0.375 9.5D516 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 7.991
40、6 14.3 5.37 136.4 0.125 3.2K332 2.414 6.4 2.20 55.9 0.125 3.2FIG. 2 Test Chamber Purge, Pressurization, and Vent LinesG740837.4 No personnel shall be permitted in the test cell whenremotely controlled valves are operated or when testing is inprogress.7.5 The housekeeping and maintenance characterist
41、ics ofthe test area shall be considered for both safety and cleanlinessaspects.7.6 Oxygen:Warning! Oxygen vigorously accelerates combustion.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
42、cleaning to remove oil, grease, and other combus-tibles.Keep combustibles away from oxygen and eliminate ignitionsources.Keep surfaces clean to prevent ignition or explosion, or both,on contact with oxygen.Always use a pressure regulator. Release regulator tensionbefore opening cylinder valve.All eq
43、uipment and containers used must be suitable andrecommended for oxygen service.Never attempt to transfer oxygen from cylinder in which 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 no
44、t in use.Stand away from outlet when opening cylinder valve.For technical use only. Do not use for inhalation purposes.Keep cylinder out 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 Ga
45、s 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 thickness 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 o
46、ther than 0.060 6 0.005 in., note thedeviation. The specimens shall be representative of the as-usedcondition. The as-used condition may 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. Prep
47、are andhandle the specimens with new, visibly clean, vinyl surgicalgloves or equivalent. Do not touch the materials or specimenswith bare 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
48、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 thickness 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 manuf
49、acturers 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 greases and semisolid material, fill thesample area of the test chamber subassembly to a depth of0.060 6 0.005 in. (1.52 6 0.13 mm).8.3.5 Irregular materials may be pr
