ASTM D7559/D7559M-09(2020)
(Test Method)Standard Test Method for Determining Pressure Decay of Inflatable Restraint Cushions
Standard Test Method for Determining Pressure Decay of Inflatable Restraint Cushions
SIGNIFICANCE AND USE
5.1 This test method may be used for product development and design, production validation, manufacturing process control, lot acceptance, or for a combination thereof.
5.2 The rate of inflation in this method does not attempt to mimic that of an actual cushion deployment, nor is it intended to subject the cushion to the dynamic loads, stress, and temperatures during such an event. It is also recognized that the compressed air used for this tests may not leak through the cushion at the same rate as the gas or mixture of gasses typically used in cushion inflators. Rather this method is intended to give a relative indication of the pressure holding ability of the cushion.
5.3 The internal volume and internal design of cushions varies greatly. This test method is most useful when comparing data from cushions of the same design and volume. This test method does not provide any data concerning the volume of gas leaking from the bag. At certain higher levels of the initial internal pressure, this test method will irreversibly damage the cushion and change its leakage properties for future testing or for commercial use. The damage to the bag is dependent on the design or shape of a specific bag and the type of coating applied. It is the responsibility of the supplier and/or purchaser to determine if the parameters under which a cushion is tested will be destructive and render the cushion unfit for future use
5.4 Within the limits of variance expressed in Section 12, this test method is useful for design and production validation and may be suitable for incorporation in a cushion specification or for lot acceptance testing of commercial shipments.
SCOPE
1.1 This test method is intended to determine the ability of an inflatable restraint cushion to retain air pressure at elevated pressures for a specified time interval.
1.2 Procedures and apparatus other than those stated in this test method may be used by agreement of purchaser and supplier, provided the specific deviations from the standard acknowledged in the report.
1.3 The results of this test method should not be used to predict the actual internal pressure decay of a cushion during a deployment.
1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.5 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7559/D7559M −09 (Reapproved 2020)
Standard Test Method for
Determining Pressure Decay of Inflatable Restraint
Cushions
This standard is issued under the fixed designation D7559/D7559M; 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 E691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
1.1 This test method is intended to determine the ability of
D6799 Terminology Relating to Inflatable Restraints
an inflatable restraint cushion to retain air pressure at elevated
pressures for a specified time interval.
3. Terminology
1.2 Procedures and apparatus other than those stated in this
3.1 For all terminology relating to D13.20, Inflatable
test method may be used by agreement of purchaser and
restraints, refer to Terminology D6799.
supplier, provided the specific deviations from the standard
3.1.1 The following terms are relevant to this standard:
acknowledged in the report.
deployment; inflatable restraint.
1.3 The results of this test method should not be used to
3.2 For all other terms related to textiles, see Terminology
predict the actual internal pressure decay of a cushion during a
D123.
deployment.
4. Summary of Test Method
1.4 The values stated in either SI units or inch-pound units
are to be regarded separately as standard. The values stated in
4.1 After inflation with air to a specific initial internal
each system may not be exact equivalents; therefore, each
pressure, an inflatable restraint cushion is tested to for its
system shall be used independently of the other. Combining
abilitytoretainaspecifiedresidualpressure(allowingforsome
values from the two systems may result in non-conformance
pressure loss) over a specified time period.
with the standard.
4.2 An inflatable restraint cushion is mounted onto a test
1.5 This standard does not purport to address all of the
stand that allows for the inflation of the cushion to a specified
safety concerns, if any, associated with its use. It is the
initial internal pressure. After the air supply is discontinued,
responsibility of the user of this standard to establish appro-
instrumentation measures and records internal pressure drop
priate safety, health, and environmental practices and deter-
over time.
mine the applicability of regulatory limitations prior to use.
4.3 Cushion internal pressure versus time data is recorded
1.6 This international standard was developed in accor-
and compared to allowable limits agreed upon by the purchaser
dance with internationally recognized principles on standard-
and supplier.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
5. Significance and Use
mendations issued by the World Trade Organization Technical
5.1 This test method may be used for product development
Barriers to Trade (TBT) Committee.
and design, production validation, manufacturing process
control, lot acceptance, or for a combination thereof.
2. Referenced Documents
5.2 The rate of inflation in this method does not attempt to
2.1 ASTM Standards:
mimic that of an actual cushion deployment, nor is it intended
D123 Terminology Relating to Textiles
to subject the cushion to the dynamic loads, stress, and
temperaturesduringsuchanevent.Itisalsorecognizedthatthe
compressed air used for this tests may not leak through the
This test method is under the jurisdiction ofASTM Committee D13 on Textiles
and are the direct responsibility of Subcommittee D13.20 on Inflatable Restraints.
cushion at the same rate as the gas or mixture of gasses
Current edition approved Feb. 1, 2020. Published February 2020. Originally
typically used in cushion inflators. Rather this method is
approved as D7559/D7559M-09. Last previous edition approved in 2014 as
intended to give a relative indication of the pressure holding
D7559/D7559M-09(2014). DOI: 10.1520/D7559_D7559M-09R20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or ability of the cushion.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.3 The internal volume and internal design of cushions
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. varies greatly.This test method is most useful when comparing
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7559/D7559M − 09 (2020)
data from cushions of the same design and volume. This test recorded must have an accuracy of 61 %. It is optional that
method does not provide any data concerning the volume of this system can initiate the filling of the bag and the closure of
gas leaking from the bag. At certain higher levels of the initial the shut-off valve.
internal pressure, this test method will irreversibly damage the
6.8 Manual Timer (stopwatch), optional, suitable for manu-
cushion and change its leakage properties for future testing or
ally observing elapsed time. This must have an accuracy of 61
for commercial use.The damage to the bag is dependent on the
%.
design or shape of a specific bag and the type of coating
6.9 Filter requirements, data sampling rate, transducer fre-
applied. It is the responsibility of the supplier and/or purchaser
quency response, and amplifier frequency response shall be
to determine if the parameters under which a cushion is tested
such that the overall accuracy of the data acquisition system
will be destructive and render the cushion unfit for future use
shall be within 61 %. The significant figures of the recorded
5.4 Within the limits of variance expressed in Section 12,
data of time and pressure, along with the timing increment
this test method is useful for design and production validation
should be agreed upon by the purchaser and supplier.
andmaybesuitableforincorporationinacushionspecification
or for lot acceptance testing of commercial shipments.
7. Sampling
7.1 The Cushion Pressure Decay Test at certain test param-
6. Apparatus
eters and pressures is a destructive test and therefore necessi-
6.1 Air Supply Source, capable of filling the cushion to the
tates sampling procedures if used in conjunction with lot
specified pressure, with a flow rate capable of maintaining the
acceptance.
specified pressure at equilibrium. Typically the pressure used
for testing the cushion will not exceed 200 kPa [29 psi], nor 7.2 The determination of lot size and sampling plan shall be
will the flow exceed 1500 L/min [53 CFM]. The air source agreed to by purchaser and supplier.
shouldbeequippedwithaninlinefilter,shutoffvalve,andflow
7.3 One cushion assembly is a test specimen.
regulator. Care should be taken to trap out excess moisture or
oil from the compressed air source.
8. Equipment Calibration
6.2 Shut Off Valve, capable of being actuated either manu-
8.1 For inflatable restraints, all test equipment used in
ally or remotely by an electrical signal.
accordance with this test method shall be certified for calibra-
6.3 Mounting Fixture, capable of allowing a sealed attach-
tion annually using gages that are traceable to the National
ment of the cushion to the air supply source, the shut off valve,
Institute of Science and Technology (NIST) or other national
and instrumentation to monitor the pressure decay during the
standards laboratory. The test parameters of the equipment
test. It should contain a pressure pickup tube. It shall be in an
shall be tested within the operating ranges covered in the
orientation that allows free expansion of the cushion geometry.
cushion specification or equivalent document.
It should have sufficient safety shielding and isolation for
operator protection during the test. The clamping device that
9. Conditioning
attaches the opening of the cushion to the filling tube fixture
9.1 Conditioning of specimens and conducting of the testing
should be designed to properly fit the opening of the cushion,
in the standard atmosphere for testing textiles is desirable, but
provide a secure mechanical attachment, and prevent gas
not required. It is recognized that conditions of the air from the
leakage.
compressed air source used to inflate the specimen will not be
6.4 PickupTube,mountedcoaxiallyinsidefillingtubeofthe
controlled, even though care should be taken to filter the air
mounting fixture. One end should extend inside the cushion at
and trap out any excessive moisture or compressor oils.
minimum of 25 mm [1 in.] beyond the clamping device. The
9.2 Testing can be conducted in, or specimens conditioned
other end should
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