ASTM D6476-12
(Test Method)Standard Test Method for Determining Dynamic Air Permeability of Inflatable Restraint Fabrics
Standard Test Method for Determining Dynamic Air Permeability of Inflatable Restraint Fabrics
SIGNIFICANCE AND USE
For matters relating to lot acceptance of commercial shipments and conformity to specification or other standard, refer to Section 13 of this test method.
This test method is useful in the selection and design validation of permeable, uncoatable fabrics used in inflatable restraint cushions. The dynamic conditions and higher pressure differentials of this test method may better simulate the inflation and deflation cycle of an airbag module during deployment than do the steady-state conditions of Test Method D737.
5.2.1 Only uncoated, permeable fabrics should be used. Use of coated fabrics may yield invalid results and potentially damage the test apparatus.
Within the limits of variance expressed in Section 12, this test method is useful for design validation and may be suitable for incorporation in a material specification or for lot acceptance testing of commercial shipments. Caution is advised on very low permeability fabrics or with the 200 cm3. size test heat because between-laboratory precision as presented in Section 12 may be as high as 21 %.
This test method may be used for materials other than inflatable restraint fabrics which experience dynamic air permeability in sudden bursts. In such cases, the physical apparatus or its software algorithms may require modification to provide suitability for use.
Due to the split-second time interval for testing, the pressure versus time data is subject to recording anomalies and electronic noise. The data should be digitally filtered to obtain the underlying smooth pressure curve prior to data analysis. The software in the apparatus includes a reliable algorithm both to smooth the curve and to determine the exponent of air permeability.
It is inherent in the design and operation of this equipment that major components key to the calibration and measurements are specific to the individual test head. The size or permeability measuring range of the test head is typically chosen to correspond to the fabric spec...
SCOPE
1.1 This test method covers the procedures used to determine under dynamic airflow conditions the high pressure permeability of permeable, uncoated fabrics typically used for inflatable restraints. For the determination of air permeability of inflatable restraint fabrics under low pressure conditions at steady-state air flow, refer to Test Method D737.
1.2 Procedures and apparatus other than those stated in this test method may be used by agreement of purchaser and supplier with the specific deviations from the standard acknowledged in the report.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:D6476 −12
Standard Test Method for
Determining Dynamic Air Permeability of Inflatable Restraint
1
Fabrics
This standard is issued under the fixed designation D6476; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This test method covers the procedures used to deter- 3.1 For all terminology relating to D13.20, Inflatable
mine under dynamic airflow conditions the high pressure restraints, refer to Terminology D6799.
permeability of permeable, uncoated fabrics typically used for 3.1.1 The following terms are relevant to this standard:
inflatable restraints. For the determination of air permeability average dynamic air permeability (ADAP), dynamic air per-
of inflatable restraint fabrics under low pressure conditions at meability (DAP), cushion, exponent of dynamic air permeabil-
steady-state air flow, refer to Test Method D737. ity (EXP, ) inflatable restrain, inflator, module, standard atmo-
sphere for testing textiles
1.2 Procedures and apparatus other than those stated in this
test method may be used by agreement of purchaser and 3.2 For all other terms related to textiles, see Terminology
supplier with the specific deviations from the standard ac- D123.
knowledged in the report.
4. Summary of Test Method
1.3 The values stated in SI units are to be regarded as
4.1 A volume of dessicated compressed air at known vol-
standard. No other units of measurement are included in this
ume and pressure passes through a fabric specimen into the
standard.
standard atmosphere for testing textiles. During the portion of
1.4 This standard does not purport to address all of the
the test cycle which simulates airbag inflation, the pressure
safety concerns, if any, associated with its use. It is the
differential pressure across the specimen rises to a value
responsibility of the user of this standard to establish appro-
corresponding to a peak inflation pressure. During the portion
priate safety and health practices and determine the applica-
of the test cycle which simulates airbag deflation, the pressure
bility of regulatory limitations prior to use.
differential drops to 0 kPa as the air passes through the
specimen. The time to reach the maximum pressure and the
2. Referenced Documents
subsequent time to correspond to similar times in an airbag
2
2.1 ASTM Standards:
deployment.
D123 Terminology Relating to Textiles
4.2 Software algorithms integral to the apparatus smooth
D737 Test Method for Air Permeability of Textile Fabrics
out the pressure data and determine the values for ADAP and
D1776 Practice for Conditioning and Testing Textiles
EXP.
D2904 Practice for Interlaboratory Testing of a Textile Test
Method that Produces Normally Distributed Data (With-
3
5. Significance and Use
drawn 2008)
D6799 Terminology Relating to Inflatable Restraints
5.1 For matters relating to lot acceptance of commercial
E691 Practice for Conducting an Interlaboratory Study to
shipments and conformity to specification or other standard,
Determine the Precision of a Test Method
refer to Section 13 of this test method.
5.2 This test method is useful in the selection and design
1 validation of permeable, uncoatable fabrics used in inflatable
This test method is under the jurisdiction ofASTM Committee D13 on Textiles
and is the direct responsibility of Subcommittee D13.20 on Inflatable Restraints.
restraint cushions.The dynamic conditions and higher pressure
Current edition approved July 1, 2012. Published August 2012. Originally
differentials of this test method may better simulate the
approved in 2000. Last previous edition approved in 2008 as D6476–08. DOI:
inflation and deflation cycle of an airbag module during
10.1520/D6476-12.
2
deployment than do the steady-state conditions of Test Method
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contactASTM Customer Service at service@astm.org. ForAnnual Book ofASTM
D737.
Standards volume information, refer to the standard’s Document Summary page on
5.2.1 Only uncoated, permeable fabrics should be used. Use
the ASTM website.
3
of coated fabrics may yield invalid results and potentially
The last approved version of this historical standard is referenced on
www.astm.org. damage the test apparatus.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
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D6476−12
5.3 Within the limits of variance expressed in Section 12, 6.5 ElectricalFiringPulseSource,suitableforactuatingthe
this test method is useful for design validation and may b
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:D6476–08 Designation: D6476 – 12
Standard Test Method for
Determining Dynamic Air Permeability of Inflatable Restraint
1
Fabrics
This standard is issued under the fixed designation D6476; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the procedures used to determine under dynamic airflow conditions the high pressure permeability
of permeable, uncoated fabrics typically used for inflatable restraints. For the determination of air permeability of inflatable
restraint fabrics under low pressure conditions at steady-state air flow, refer to Test Method D737.
1.2 Procedures and apparatus other than those stated in this test method may be used by agreement of purchaser and supplier
with the specific deviations from the standard acknowledged in the report.
1.3The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system are not exact equivalents; therefore, each system must be used independently of the other.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
D123 Terminology Relating to Textiles
D737 Test Method for Air Permeability of Textile Fabrics
D1776 Practice for Conditioning and Testing Textiles
D2904 Practice for Interlaboratory Testing of a Textile Test Method that Produces Normally Distributed Data
D6799 Terminology Relating to Inflatable Restraints
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Terminology
3.1 For all terminology relating to D13.20, Inflatable restraints, refer to Terminology D6799.
3.1.1 The following terms are relevant to this standard: average dynamic air permeability (ADAP), dynamic air permeability
(DAP), cushion, exponent of dynamic air permeability (EXP, ) inflatable restrain, inflator, module, standard atmosphere for testing
textiles
3.2 For all other terms related to textiles, see Terminology D123.
4. Summary of Test Method
4.1 A volume of dessicated compressed air at known volume and pressure passes through a fabric specimen into the standard
atmosphere for testing textiles. During the portion of the test cycle which simulates airbag inflation, the pressure differential
pressure across the specimen rises to a value corresponding to a peak inflation pressure. During the portion of the test cycle which
simulates airbag deflation, the pressure differential drops to 0 kPa as the air passes through the specimen. The time to reach the
maximum pressure and the subsequent time to correspond to similar times in an airbag deployment.
4.2 Software algorithms integral to the apparatus smooth out the pressure data and determine the values for ADAP and EXP.
1
This test method is under the jurisdiction of ASTM Committee D13 on Textiles and is the direct responsibility of Subcommittee D13.20 on Inflatable Restraints.
Current edition approved July 1, 2008.2012. Published July 2008.August 2012. Originally approved in 2000. Last previous edition approved in 20052008 as
D6476–05.D6476–08. DOI: 10.1520/D6476-08.10.1520/D6476-12.
2
ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.ForAnnualBookofASTMStandards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
---------------------- Page: 1 ----------------------
D6476 – 12
5. Significance and Use
5.1 For matters relating to lot acceptance of commercial shipments and conformity to specification or other standard, refer to
Section 13 of this test method.
5.2 This test method is useful in the selection and design validation of permeable, uncoatable fabrics used in inflatable restraint
cushions. The dynamic conditions and higher pressure differentials of this test method may better simulate the inflatio
...
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