ASTM G124-95
(Test Method)Standard Test Method for Determining the Combustion Behavior of Metallic Materials in Oxygen-Enriched Atmospheres
Standard Test Method for Determining the Combustion Behavior of Metallic Materials in Oxygen-Enriched Atmospheres
SCOPE
1.1 This test method covers a test apparatus and technique to determine the minimum test gas pressure that supports self-sustained combustion (the threshold pressure) and the average regression rate (apparent burn rate) of a standardized sample of a metallic material that has been ignited using a strong promoter.
1.2 The data obtained from this test method are dependent on the precise test sample configuration and provide a basis for comparing the combustion behavior of materials. No criteria are implied for relating these data to the suitability of a material's use in any actual system. The application of data obtained from this test method is discussed in Guides G88 and G94.
1.3 Requirements for an apparatus suitable for this test method are given, as well as an example of such an apparatus. The example, however, is not required to be used.
1.4 This test method is for gaseous oxygen or any mixture of oxygen with diluents that will support combustion, at any pressure within the capabilities of the apparatus.
1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.6 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. Specific hazards statements are given in Section 9.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: G 124 – 95
Standard Test Method for
Determining the Combustion Behavior of Metallic Materials
in Oxygen-Enriched Atmospheres
This standard is issued under the fixed designation G 124; 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 (e) indicates an editorial change since the last revision or reapproval.
A
TABLE 1 Example Data Set for Type 316 Stainless Steel
1. Scope
Number of Samples
1.1 This test method covers a test apparatus and technique
Material Pressure, MPa
Partial Burn Complete Burn
to determine the minimum test gas pressure that supports
UNS 31600 1.75 10 0
3.45 8 2
self-sustained combustion (the threshold pressure) and the
6.90 0 10
average regression rate (apparent burn rate) of a standardized
A
These data were produced at NASA White Sands Test Facility, New Mexico,
sample of a metallic material that has been ignited using a
strong promoter.
1.2 The data obtained from this test method are dependent
BB-0-925 Oxygen, Technical, Gas and Liquid
on the precise test sample configuration and provide a basis for
2.3 Military Standard:
comparing the combustion behavior of materials. No criteria
MIL-0-27210E Amendment 1—Oxygen, Aviator’s Breath-
are implied for relating these data to the suitability of a
ing, Liquid and Gas
material’s use in any actual system. The application of data
obtained from this test method is discussed in Guides G 88 and
3. Terminology
G 94.
3.1 Definitions of Terms Specific to This Standard:
1.3 Requirements for an apparatus suitable for this test
3.1.1 average regression rate (apparent burn rate)—the
method are given, as well as an example of such an apparatus.
average rate at which the burning/solid-metal interface ad-
The example, however, is not required to be used.
vances along the test sample length.
1.4 This test method is for gaseous oxygen or any mixture
3.1.2 igniter—a material to ignite the promoter that can
of oxygen with diluents that will support combustion, at any
burn under an electrical influence, such as a small-diameter
pressure within the capabilities of the apparatus.
wire.
1.5 The values stated in SI units are to be regarded as the
3.1.3 promoter—a material that can add supplemental heat
standard. The values given in parentheses are for information
and increase the temperature to start combustion of the material
only.
being tested.
1.6 This standard does not purport to address all of the
3.1.4 self-sustained combustion—combustion that con-
safety concerns, if any, associated with its use. It is the
sumes a sample to the point at which the sample holder affects
responsibility of the user of this standard to establish appro-
further combustion (assuming sufficient oxygen).
priate safety and health practices and determine the applica-
3.1.5 threshold pressure—the minimum gas pressure (at a
bility of regulatory limitations prior to use. Specific hazards
specified oxygen concentration and ambient temperature) that
statements are given in Section 9.
supports self-sustained combustion of the entire standard
2. Referenced Documents
sample.
2.1 ASTM Standards:
4. Summary of Test Method
G 88 Guide for Designing Systems for Oxygen Service
4.1 A small rod of the material is suspended in a chamber
G 93 Practice for Cleaning Methods for Material and
filled with pressurized test gas. The chamber contains sufficient
Equipment Used in Oxygen-Enriched Environments
oxygen so that not more than 10 % of the oxygen will be
G 94 Guide for Evaluating Metals for Oxygen Service
consumed when the material combusts completely. A promoter
2.2 Federal Specification:
(typically aluminum or magnesium) applied to the bottom of
the rod starts combustion of the material. The test pressure is
reduced and another rod is tested if combustion of the entire
This test method is under the jurisdiction of ASTM Committee G-4 on
rod occurs. This continues until self-sustained combustion of
Compatibility and Sensitivity of Material in Oxygen Enriched Atmospheres and is
the direct responsibility of Subcommittee G04.01 on Test Methods.
Current edition approved Feb. 15, 1995. Published August 1995. Originally
published as G 124 – 94. Last previous edition G 124 – 94. Available from Standardization Documents Order Desk, Bldg 4 Section D, 700
Annual Book of ASTM Standards, Vol 14.02. Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
G 124
the rod does not occur for at least five tests at one pressure. The
lowest pressure at which self-sustained combustion occurred is
the threshold pressure for the material, and the difference
between it and the highest pressure level that produced only
incomplete combustion is the margin of potential error. Astute
initial estimates of the threshold can reduce the amount of
testing necessary to demonstrate the threshold to within the
required uncertainty.
5. Significance and Use
5.1 This test method will allow comparisons of the combus-
tion characteristics of various metallic materials. The combus-
tion characteristics that can be evaluated include (1) threshold
pressure and (2) average regression rate (apparent burn rate) of
the sample.
6. Interferences
6.1 Any internal materials that may bake out or vaporize
during the combustion process at test temperature/pressure
may interfere with the chemistry of the fire propagation.
6.2 The specific atmosphere in the test chamber can have a
severe effect. Therefore, alien air, argon, nitrogen, carbon
dioxide, moisture, and others can be important interfering
FIG. 1 Schematic of Typical System
gases.
6.3 The test is conducted under stagnant conditions. A
flowing system or one that facilitates buoyant convective
currents may be a significantly more severe climate.
6.4 The specific temperature of the test sample prior to
ignition can have an important effect.
NOTE 1—The promoters discussed in this test method have produced
favorable results over a wide range of metal test specimens with the
degree of precision sought to date. As the threshold is approached or when
interaction between promoter and metal occur promoter can thwart the
ignition process. Hence the prospect that future work may refine the
promoter and enable the measurement of lower thresholds than are
measurable today cannot be ruled out.
7. Apparatus
7.1 A schematic of a typical system is shown in Fig. 1.
Other designs may also be used, if they fulfill the requirements
below.
7.2 Test Chamber—A cross-section of a typical stainless
steel test chamber is shown in Fig. 2. No more than 10 % of the
available oxygen should be consumed during a test. Appendix
X1 provides criteria for establishing the lowest test pressures
that meet this criterion for various vessel volumes. If the
chamber cannot be made sufficiently large, an accumulator can
be attached that contains more test gas if the chamber cannot be
made sufficiently large; however, this is not as severe a test
FIG. 2 Typical Stainless Steel Test Chamber Cross-Section
environment as in the larger vessel. The test chamber shall not
contribute any chemical interference to testing.
less, occur due to depletion of oxygen, consequential reduction of
NOTE 2—The addition of an accumulator can act as a snubber to
pressure, or concentration of diluents. However, in any test in which
suppress pressure rises that occur due to temperature rises and pressure
complete combustion of the specimen occurs, the result is valid, regardless
drops that result from oxygen consumption, but it will have a much
of whether the test conditions met the minimum recommended require-
smaller effect in preventing local buildup of diluents in the oxygen. Each
ment for oxygen inventory.
of these influences will exhibit a progressively greater effect and conse-
7.3 Sample holder, capable of securing the sample at the top
quence in smaller vessels.
and supporting it in a vertical position. There shall be sufficient
NOTE 3—The significance of ensuring an adequate oxygen inventory is
space beneath the sample for the igniter and any drops of liquid
to avoid the observation of apparently negative test results at conditions
that are above the threshold but for which extinguishment may, nonethe- material that may fall during the test.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
G 124
when used with oxygen mixed with other gases, alterations to the test
7.4 Thermocouple, used to measure gas temperature in the
method may be necessary. At present, these alterations have not been
chamber.
studied sufficiently for inclusion in this test method.
7.5 Pressure Transducer, used to measure gas pressure in
8.2 Promoter—The promoter shall consist of a sufficient
the chamber, accurate to within 6 1 % of reading.
7.6 Liner and Base Plate—A burn-resistant (for example, quantity of material to ignite the test specimens. Some ex-
amples of promoter material are aluminum and magnesium (3).
copper) liner and base plate in the test chamber serve as an
internal shield to protect the components from combustion No promoter may be necessary at all at times; the igniter wire
itself may provide sufficient energy to ignite the sample.
products, molten slag, and so forth.
7.7 Sight Glass, capable of withstanding the maximum test Nonmetallic promoters may be used; however, the combustion
products of such promoters might contaminate the test media.
pressure anticipated. If video or film recording of the burning
event contained in the test chamber is desired, the sight glass
NOTE 5—In selecting the promoter material, the possibility of a
shall transmit compatible light.
chemical reaction between the test material and the promoter should be
7.8 Igniter Power Supply, electrically isolated and capable
considered. Also, for certain metals, the chemical energy released from the
of providing adequate current to initiate the igniter wire within combustion of promoter might be insufficient to ignite the metal. Other
ignition sources, for example, electrical or laser, may be used in such
a few seconds of the application of power.
cases.
7.9 Test Cell, (a room to house the test chamber), con-
structed of noncombustible material (such as concrete or metal)
8.3 Igniter Wire—The igniter wire shall be made of a
with sufficient strength to provide protection from explosion or material capable of igniting the promoter. Some examples of
fire hazards. A continuous ventilation system shall circulate
the igniter wire material are nickel/chromium or aluminum/
fresh air in the test cell. The cell shall provide a facility that can
palladium.
be maintained at a high level of good housekeeping. The test
9. Hazards
cell shall be cleaned periodically to avoid contamination of the
sample and equipment.
9.1 High-Pressure Oxygen System—Warning: There are
7.10 Piping System, which purges, pressurizes, and vents
hazards involving the use of a high-pressure oxygen system.
the test chamber. The piping system shall be designed to permit
The following guidelines will reduce the dangers:
remote test chamber purge, pressurization, and venting without
9.1.1 Personnel should be isolated from the test system
unsafe exposure of personnel. The chamber shall be purged and
when it is pressurized. Preferably, personnel should be shielded
pressurized through one line and vented through a separate line
by both physical protection (for example, the test cell) and
to minimize the chances of contaminant migrating into the
distance.
pressurization line, which might influence subsequent tests. A
9.1.2 The test system itself should be isolated to prevent
typical piping system for this test is shown in Fig. 1.
danger to people not involved in the test.
7.11 Control Area, which will isolate test personnel from the
9.1.3 The test system should incorporate equipment able to
test cell during tests. This control area shall be provided with
handle the maximum operating pressure safely, including an
the necessary control and instrumentation features to perform
appropriate safety-factor.
test chamber purge, pressurization and venting operations, and
9.1.4 The system should be kept clean to prevent uninten-
monitoring of the test chamber instrumentation during the test.
tional ignition.
7.12 Data Acquisition System (Optional), capable of record-
9.1.5 The test system should be double-isolated from the
ing, storing, and accessing the pressure and temperature data at
test gas supply system.
a rate of ten samples/s (minimum). It shall also include a video
9.1.6 Remote readout devices should be provided so per-
recording device that displays the “real-time” burn phenom-
sonnel do not have to approach the test system to obtain
enon. The video recording can be used for regression rate
operating data.
determination.
9.2 Oxygen—Warning: Oxygen enrichment accelerates
combustion vigorously. Care should be taken at all times when
8. Reagents and Materials
working with oxygen. CGA Pamphlets G-4.0 (4) and G-4.1 (5)
8.1 Gaseous Oxygen—Oxygen purity equal to or greater
and Practice G 93 provide further details.
than that of practical systems is preferred, especially when
9.3 Metal Oxides—Warning: Toxic metal and oxide dusts
testing alloys containing aluminum, magnesium, zirconium,
may be produced when using this test method. These dusts are
etc. (that is, metals believed to burn at least in part in the vapor
often toxic to breathe or touch; safety procedures appropriate to
phase). An analysis of the test oxidant is required. The use of
the hazard must therefore be followed.
oxygen greater than 99.5 % pure may affect the test results
9.4 Vessel Failures—Warning: The vessel described in this
significantly (1), and its use shall be noted on the data sheet.
experiment has contained the combustion of ferrous, alumi-
num, and copper alloys successfully. Molten metal slags
NOTE 4—Some applications involve the use of oxygen mixed with
produced in these tests can be very destructive, and as pressure
other gases, and data in the literature (1, 2) indicate that the rankings of
or oxygen purity increases, the intensity of the combustion
materials can be different depending on the amount and kind of diluents
present. Although the basic apparatus and principle of this test are valid
The trade name for aluminum-palladium wire is Py
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