ASTM_G_74_-_13.pdf

Designation:G7413Standard Test Method forIgnition Sensitivity of Nonmetallic Materials andComponents by Gaseous Fluid Impact1This standard is issued under the fixed designation G74;the number immediately following the designation indicates the year of originaladoption or,in the case of revision,the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method describes a method to determine therelative sensitivity of nonmetallic materials(including plastics,elastomers,coatings,etc.)and components(including valves,regulators flexible hoses,etc.)to dynamic pressure impacts bygases such as oxygen,air,or blends of gases containingoxygen.1.2 This test method describes the test apparatus and testprocedures employed in the evaluation of materials and com-ponents for use in gases under dynamic pressure operatingconditions up to gauge pressures of 69 MPa and at elevatedtemperatures.1.3 This test method is primarily a test method for rankingof materials and qualifying components for use in gaseousoxygen.The material test method is not necessarily valid fordetermination of the sensitivity of the materials in an“as-used”configuration since the material sensitivity can be alteredbecause of changes in material configuration,usage,andservice conditions/interactions.However,the component test-ing method outlined herein can be valid for determination ofthe sensitivity of components under service conditions.Thecurrent provisions of this method were based on the testing ofcomponents having an inlet diameter(ID bore)less than orequal to 14 mm(see Note 1).1.4 A 5 mm Gaseous Fluid Impact Sensitivity(GFIS)testsystem and a 14 mm GFIS test system are described in thisstandard.The 5 mm GFIS system is utilized for materials andcomponents that are directly attached to a high-pressure sourceand have minimal volume between the material/component andthe pressure source.The 14 mm GFIS system is utilized formaterials and components that are attached to a high pressuresource through a manifold or other higher volume or largersized connection.Other sizes than these may be utilized but noattempt has been made to characterize the thermal profiles ofother volumes and geometries(see Note 1).NOTE1The energy delivered by this test method is dependent on thegas volume being rapidly compressed at the inlet to the test specimen ortest article.Therefore the geometry of the upstream volume(diameter andlength)is crucial to the test and crucial to the application of the results toactual service conditions.It is therefore recommended that caution beexercised in applying the results of this testing to rapid pressurization ofvolumes larger than those standardized by this test method.This energydelivered by this standard is based on the rapid compression of the volumein either a 5 mm ID by 1000 mm long impact tube or a 14 mm ID by 750mm long impact tube.These two upstream volumes are specified in thisstandard based on historic application within the industry.1.5 This test method can be utilized to provide batch-to-batch comparison screening of materials when the data isanalyzed according to the methods described herein.Accept-ability of any material by this test method may be based on its50%reaction pressure or its probability of ignition based on alogistic regression analysis of the data(described herein).1.6 Many ASTM,CGA,and ISO test standards requireignition testing of materials and components by gaseous fluidimpact,also referred to as adiabatic compression testing.Thistest method provides the test system requirements consistentwith the requirements of these other various standards.Thepass/fail acceptance criteria may be provided within otherstandards and users should refer to those standards.Pass/failguidance is provided in this standard such as that noted insection 4.6.This test method is designed to ensure thatconsistent gaseous fluid impact tests are conducted in differentlaboratories.1.7 The criteria used for the acceptance,retest,andrejection,or any combination thereof of materials and compo-nents for any given application shall be determined by the userand are not fixed by this method.However,it is recommendedthat at a minimum the 95%confidence interval be establishedfor all test results since ignition by this method is inherentlyprobabilistic and should be treated by appropriate statisticalmethods.1.8 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1This test method is under the jurisdiction of ASTM Committee G04 onCompatibility and Sensitivity of Materials in Oxygen Enriched Atmospheres and isthe direct responsibility of Subcommittee G04.01 on Test Methods.Current edition approved May 1,2013.Published October 2013.Originallyapproved in 1982.Last previous edition approved in 2008 as G74 08.DOI:10.1520/G0074-13.Copyright ASTM International,10