ASTM_D_7559_-_D_7559M_-_09_2014.pdf

Designation:D7559/D7559M09(Reapproved 2014)Standard Test Method forDetermining Pressure Decay of Inflatable RestraintCushions1This standard is issued under the fixed designation D7559/D7559M;the number immediately following the designation indicates theyear of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of lastreapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method is intended to determine the ability ofan inflatable restraint cushion to retain air pressure at elevatedpressures for a specified time interval.1.2 Procedures and apparatus other than those stated in thistest method may be used by agreement of purchaser andsupplier,provided the specific deviations from the standardacknowledged in the report.1.3 The results of this test method should not be used topredict the actual internal pressure decay of a cushion during adeployment.1.4 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard.The values stated ineach system may not be exact equivalents;therefore,eachsystem shall be used independently of the other.Combiningvalues from the two systems may result in non-conformancewith the standard.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 regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodD6799 Terminology Relating to Inflatable Restraints3.Terminology3.1 For all terminology relating to D13.20,Inflatablerestraints,refer to Terminology D6799.3.1.1 The following terms are relevant to this standard:deployment;inflatable restraint.3.2 For all other terms related to textiles,see TerminologyD123.4.Summary of Test Method4.1 After inflation with air to a specific initial internalpressure,an inflatable restraint cushion is tested to for itsability to retain a specified residual pressure(allowing for somepressure loss)over a specified time period.4.2 An inflatable restraint cushion is mounted onto a teststand that allows for the inflation of the cushion to a specifiedinitial internal pressure.After the air supply is discontinued,instrumentation measures and records internal pressure dropover time.4.3 Cushion internal pressure versus time data is recordedand compared to allowable limits agreed upon by the purchaserand supplier.5.Significance and Use5.1 This test method may be used for product developmentand design,production validation,manufacturing processcontrol,lot acceptance,or for a combination thereof.5.2 The rate of inflation in this method does not attempt tomimic that of an actual cushion deployment,nor is it intendedto subject the cushion to the dynamic loads,stress,andtemperatures during such an event.It is also recognized that thecompressed air used for this tests may not leak through thecushion at the same rate as the gas or mixture of gassestypically used in cushion inflators.Rather this method isintended to give a relative indication of the pressure holdingability of the cushion.5.3 The internal volume and internal design of cushionsvaries greatly.This test method is most useful when comparingdata from cushions of the same design and volume.This testmethod does not provide any data concerning the volume ofgas leaking from the bag.At certain higher levels of the initialinternal pressure,this test method will irreversibly damage thecushion and change its leakage properties for future testing orfor commercial use.The damage to the bag is dependent on thedesign or shape of a specific bag and the type of coating1This test method is under the jurisdiction ofASTM Committee D13 on Textilesand are the direct responsibility of Subcommittee D13.20 on Inflatable Restraints.Current edition approved July 1,2014.Published August 2014.Originallyapproved as D7559/D7559M-09.Last previous edition approved in 2009 asD7559/D7559M-09.DOI:10.1520/D7559_D7559M-09R14.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 applied.It is the responsibility of the supplier and/orpurchaser to determine if the parameters under which a cushionis tested will be destructive and render the cushion unfit forfuture use5.4 Within the limits of variance expressed in Section 12,this test method is useful for design and production validationand may be suitable for incorporation in a cushion specificationor for lot acceptance