ASTM G125-00(2008)
(Test Method)Standard Test Method for Measuring Liquid and Solid Material Fire Limits in Gaseous Oxidants
Standard Test Method for Measuring Liquid and Solid Material Fire Limits in Gaseous Oxidants
SIGNIFICANCE AND USE
This test method provides for measuring of the minimum conditions of a range of parameters (concentration of oxidant in a flowing mixture of oxidant and diluent, pressure, temperature) that will just support sustained propagation of combustion. For materials that exhibit flaming combustion, this is a flammability limit similar to the lower flammability limit, upper flammability limit, and minimum oxidant for combustion of gases (1). However, unlike flammability limits for gases, in two-phase systems, the concept of upper and lower flame limits is not meaningful. However, limits can typically be determined for variations in other parameters such as the minimum oxidant for combustion (the oxidant index), the pressure limit, the temperature limit, and others. Measurement and use of these data are analogous to the measurement and use of the corresponding data for gaseous systems. That is, the limits apply to systems likely to experience complete propagations (equilibrium combustion). Successful ignition and combustion below the measured limits at other conditions or of a transient nature are not precluded below the threshold. Flammability limits measured at one set of conditions are not necessarily the lowest thresholds at which combustion can occur. Therefore direct correlation of these data with the burning characteristics under actual use conditions is not implied.
SCOPE
1.1 This test method covers a procedure for measuring the threshold-limit conditions to allow equilibrium of combustion of materials in various oxidant gases under specific test conditions of pressure, temperature, flow condition, fire-propagation directions, and various other geometrical features of common systems.
1.2 This test method is patterned after Test Method D 2863-95 and incorporates its procedure for measuring the limit as a function of oxidant concentration for the most commonly used test conditions. Sections 8, 9, 10, 11, 13, and 14 for the basic oxidant limit (oxygen index) procedure are quoted directly from Test Method D 2863-95. Oxygen index data reported in accordance with Test Method D 2863-95 are acceptable substitutes for data collected with this standard under similar conditions.
1.3 This test method has been found applicable to testing and ranking various forms of materials. It has also found limited usefulness for surmising the prospect that materials will prove “oxygen compatible” in actual systems. However, its results do not necessarily apply to any condition that does not faithfully reproduce the conditions during test. The fire limit is a measurement of a behavioral property and not a physical property. Uses of these data are addressed in Guides G 63 and G 94.
Note 1—Although this test method has been found applicable for testing a range of materials in a range of oxidants with a range of diluents, the accuracy has not been determined for many of these combinations and conditions of specimen geometry, outside those of the basic procedure as applied to plastics.
Note 2—Test Method D 2863-95 has been revised and the revised Test Method has been issued as D 2863-97. The major changes involve sample dimensions, burning criteria and the method for determining the oxygen index. The aim of the revisions was to align Test Method D 2863 with ISO 4589-2. Six laboratories conducted comparison round robin testing on self-supporting plastics and cellular materials using D 2863-95 and D 2863-97. The results indicate that there is no difference between the means provided y the two methods at the 95 % confidence level. No comparison tests were conducted on thin films. The majority of ASTM Committee G4 favors maintaining the D 2863-95 as the backbone of G 125 until comprehensive comparison data become available.
1.4 One very specific set of test conditions for measuring the fire limits of metals in oxygen has been codified in Test Method G 124. Test Method G 124 measures the minimum pressure limit in ...
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Designation: G125 − 00(Reapproved 2008)
Standard Test Method for
Measuring Liquid and Solid Material Fire Limits in Gaseous
Oxidants
This standard is issued under the fixed designation G125; 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.
Method has been issued as D2863-97. The major changes involve sample
1. Scope
dimensions, burning criteria and the method for determining the oxygen
1.1 This test method covers a procedure for measuring the
index.The aim of the revisions was to alignTest Method D2863 with ISO
threshold-limit conditions to allow equilibrium of combustion 4589-2. Six laboratories conducted comparison round robin testing on
self-supportingplasticsandcellularmaterialsusingD2863-95andD2863-
of materials in various oxidant gases under specific test
97. The results indicate that there is no difference between the means
conditions of pressure, temperature, flow condition, fire-
provided y the two methods at the 95 % confidence level. No comparison
propagation directions, and various other geometrical features
tests were conducted on thin films. The majority ofASTM Committee G4
of common systems.
favors maintaining the D2863-95 as the backbone of G125 until compre-
hensive comparison data become available.
1.2 This test method is patterned after Test Method
1.4 One very specific set of test conditions for measuring
D2863-95 and incorporates its procedure for measuring the
limit as a function of oxidant concentration for the most the fire limits of metals in oxygen has been codified in Test
Method G124. Test Method G124 measures the minimum
commonly used test conditions. Sections 8, 9, 10, 11, 13, and
forthebasicoxidantlimit(oxygenindex)procedurearequoted pressure limit in oxygen for its own set of test conditions. Its
details are not reproduced in this standard. A substantial
directly from Test Method D2863-95. Oxygen index data
reportedinaccordancewithTestMethodD2863-95areaccept- database is available for this procedure, although it is much
smaller than the database for Test Method D2863-95.
able substitutes for data collected with this standard under
similar conditions. (Warning—During the course of combustion, gases, vapors,
aerosols, fumes or any combination of these are evolved which
1.3 This test method has been found applicable to testing
may be hazardous.) (Warning—Adequate precautions should
and ranking various forms of materials. It has also found
be taken to protect the operator.)
limitedusefulnessforsurmisingtheprospectthatmaterialswill
prove “oxygen compatible” in actual systems. However, its 1.5 The values stated in SI units are to be regarded as the
results do not necessarily apply to any condition that does not
standard. No other units of measurement are included in this
faithfully reproduce the conditions during test. The fire limit is standard.
a measurement of a behavioral property and not a physical
1.6 This basic standard should be used to measure and
property. Uses of these data are addressed in Guides G63 and
describe the properties of materials, products, or assemblies in
G94.
response to heat and flame under controlled laboratory con-
ditions and should not be used to directly describe or appraise
NOTE 1—Although this test method has been found applicable for
testing a range of materials in a range of oxidants with a range of diluents,
the fire hazard or fire risk of materials, products or assemblies
the accuracy has not been determined for many of these combinations and
under actual fire conditions. However, results of this test may
conditions of specimen geometry, outside those of the basic procedure as
be used as elements of a fire risk assessment which takes into
applied to plastics.
account all of the factors which are pertinent to an assessment
NOTE 2—Test Method D2863-95 has been revised and the revised Test
of the fire hazard of a particular end use. The standard has
more applicability in this regard at predicting the fire behavior
This test method is under the jurisdiction of ASTM Committee G04 on
of materials and components that are close in size to the test
Compatibility and Sensitivity of Materials in Oxygen EnrichedAtmospheres and is
condition, than for systems that are much different (for ex-
the direct responsibility of Subcommittee G04.01 on Test Methods. Portions have
been adopted from Test Method D2863-95 that is under the jurisdiction of ASTM
ample: comparing a test rod to a valve seat rather than
Committee D20 on Plastics.
comparing a test rod to a house or a particle)
Current edition approved April 1, 2008. Published July 2008. Originally
1.7 This standard does not purport to address all of the
approved in 1994. Last previous edition approved in 2000 as G125 – 00. DOI:
10.1520/G0125-00R08. safety concerns, if any, associated with its use. It is the
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G125 − 00 (2008)
responsibility of the user of this standard to establish appro- 3.2.2 oxidant compatibility, n—the ability of a substance to
priate safety and health practices and determine the applica- coexist with both an oxidant and a potential source(s) of
bility of regulatory limitations prior to use. ignition within the acceptable risk parameter of the user (at an
expected pressure and temperature).
2. Referenced Documents
3.2.3 oxidant index, n—the minimum concentration of an
2.1 ASTM Standards:
oxidant such as oxygen, nitrous oxide, fluorine, etc., expressed
D618 Practice for Conditioning Plastics for Testing
as a volume percent, in a mixture of the oxidant with a diluent
D1071 Test Methods for Volumetric Measurement of Gas-
such as nitrogen, helium, carbon dioxide, etc., that will just
eous Fuel Samples
support sustained combustion of a material initially at given
D2444 Test Method for Determination of the Impact Resis-
conditions of temperature, pressure, flow conditions, propaga-
tance of Thermoplastic Pipe and Fittings by Means of a
tion direction, etc. (See also, oxygen index.)
Tup (Falling Weight)
3.2.3.1 Discussion—The oxidant index may be more spe-
D2863 Test Method for Measuring the Minimum Oxygen
cifically identified by naming the oxidant: oxygen limit (or
Concentration to Support Candle-Like Combustion of
index), nitrous oxide limit (or index), fluorine limit (or index),
Plastics (Oxygen Index)
etc. Unless specified otherwise, the typical oxidant is taken to
D2863-95 TestMethodforMeasuringtheMinimumOxygen be oxygen, the typical diluent is taken to be nitrogen, and the
Concentration to Support Candle-Like Combustion of
typical temperature is taken as room temperature.
Plastics (Oxygen Index)
3.2.4 pressure limit—the minimum pressure of an oxidant
D2863-97 TestMethodforMeasuringtheMinimumOxygen
(or mixture) that will just support sustained combustion of a
Concentration to Support Candle-Like Combustion of
material initially at given conditions of oxidant concentration,
Plastics (Oxygen Index)
temperature, flow condition, propagation direction, etc.
G63 Guide for Evaluating Nonmetallic Materials for Oxy-
3.2.4.1 Discussion—The pressure limit may be more spe-
gen Service
cifically identified by naming the oxidant: oxygen pressure
G94 Guide for Evaluating Metals for Oxygen Service
limit, nitrous oxide pressure limit, fluorine pressure limit, etc.
G124 Test Method for Determining the Combustion Behav-
3.2.5 temperature limit—the minimum temperature of an
ior of Metallic Materials in Oxygen-Enriched Atmo-
oxidant (or mixture) that will just support sustained combus-
spheres
tion of a material initially at given conditions of oxidant
G128 Guide for Control of Hazards and Risks in Oxygen
concentration, temperature, flow condition, propagation
Enriched Systems
direction, etc.
2.2 Other Standards:
3.2.5.1 Discussion—The temperature limit may be more
ISO 4589-2 Plastics—Determination of burning behavior by
specifically identified by naming the oxidant: oxygen tempera-
oxygen index—Part 2: Ambient temperature test
ture limit, nitrous oxide temperature limit, fluorine temperature
limit, etc.
3. Terminology
3.1 Definitions:
4. Summary of Test Method
3.1.1 oxygen compatibility, n—the ability of a substance to
4.1 The threshold limit condition (minimum oxidant
coexist with both oxygen and a potential source(s) of ignition
concentration, minimum pressure, minimum temperature, etc.)
within the acceptable risk parameter of the user (at an expected
that will just support sustained combustion under equilibrium
pressure and temperature). (See Guide G128.)
conditions is measured in a test apparatus. The equilibrium is
3.1.2 oxygen index, n—the minimum concentration of
established by the relation between the heat generated from the
oxygen, expressed as a volume percent, in a mixture of oxygen
combustion of the specimen (that may be augmented by the
and nitrogen that will just support flaming combustion of a
heat of decomposition of some oxidants) and the heat lost to
material initially at room temperature under the conditions of
the surroundings as measured by one or the other of two
Test Method D2863. (See Test Method D2863.)
arbitrary criteria, namely, a time of burning or a length of
specimen burned. This point is approached from both sides of
3.2 Definitions of Terms Specific to This Standard:
the critical threshold condition in order to establish the fire
3.2.1 fire limit, n—the threshold limit conditions that will
limit.
just support sustained combustion of a material under a
combination of specified conditions and at least one variable
5. Significance and Use
parameter (typically oxidant concentration, diluent nature,
pressure, temperature, geometry, flow or flame parameters, 5.1 This test method provides for measuring of the mini-
etc.).
mum conditions of a range of parameters (concentration of
oxidant in a flowing mixture of oxidant and diluent, pressure,
temperature) that will just support sustained propagation of
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
combustion. For materials that exhibit flaming combustion,
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
ISO 4589-2 First edition 1996-07-15, International Organization for
Standardization, Geneve, Switzerland, 1996.
G125 − 00 (2008)
this is a flammability limit similar to the lower flammability materials. Care is necessary in comparing materials that have
limit, upper flammability limit, and minimum oxidant for not been tested in similar procedures.
combustion of gases (1). However, unlike flammability limits
7.2 Oxidants—Changing the oxidant may cause the greatest
for gases, in two-phase systems, the concept of upper and
changes in results for other constant conditions (1, 2, 3).
lower flame limits is not meaningful. However, limits can
Oxidants behave dramatically different, because their basic
typically be determined for variations in other parameters such
chemistry with differing materials is different. For example,
as the minimum oxidant for combustion (the oxidant index),
even though nitrous oxide is a combination of nitrogen and
the pressure limit, the temperature limit, and others. Measure-
oxygen, it behaves much differently than a similar oxygen/
ment and use of these data are analogous to the measurement
nitrogen mixture. During combustion, nitrous oxide decom-
and use of the corresponding data for gaseous systems.That is,
poses to release heat that renders it more able to support
the limits apply to systems likely to experience complete
combustion than a simple mixture. Fluorine is very reactive
propagations (equilibrium combustion). Successful ignition
and produces more gaseous product species which changes its
and combustion below the measured limits at other conditions
behavior in higher purity oxidant. There are data available in
or of a transient nature are not precluded below the threshold.
varying amounts for the oxidants: oxygen, nitrous oxide,
Flammability limits measured at one set of conditions are not
fluorine, nitrogen trifluoride, and nitrogen (nitrogen is an
necessarily the lowest thresholds at which combustion can
oxidant in some cases, a diluent in others).
occur. Therefore direct correlation of these data with the
burning characteristics under actual use conditions is not
7.3 Diluents—Varying diluents can have a significant effect
implied.
although much less impressive than oxidant, pressure or even
flow direction (1-8). Diluent’s thermal conductivity and heat
6. Abstract
capacityappeartobethemostsignificantproperties.Reactivity
is a second issue. For example, nitrogen does not participate in
6.1 A well-established procedure for measuring an oxidant
most polymer combustions but can react with some metals and
limit,theoxygenindex,ofplastics(SeeTestMethodD2863)is
exhibit widely different diluent natures. Among the diluents
reviewed, then variations commonly used to collect data for
used to date are nitrogen, helium, argon, carbon dioxide, neon,
oxidant compatibility purposes are described. In the test, a
and xenon.
series of specimens is placed in a preadjusted oxidant mixture
and deliberately ignited. Specimens that do not “burn” are
7.4 Pressures—Pressure has a dramatic effect on the fire
retested in higher concentrations. Specimens that do burn are
limit (1, 4, 5, 8, 9, 10, 11).The role of pressure is complex, yet
retested in lower concentrations. When the operator is confi-
it is one of the most important variables because oxygen
dent that the threshold has been determined by a suitable
systems employ a range of pressures to 82 MPa (12000 psig).
number and spread of negative tests below the threshold, the
7.5 Temperatures—The fole of temperature appears to be
lowest positive is reported as the oxidant index.
among the more straightforward higher temperatures appear to
6.2 Similar test methods apply when the oxidant concentra-
implylowerfirelimits.Theeffectcanbegradualorabrupt.For
tion is held constant and the temperature, pressure or other key
example PTFE will not burn in the oxygen index test at room
factor is varied. In some cases, apparatus modification or
temperature, but burns nicely at just a few degrees above room
replacement is necessary, such as a pressurized vessel is
temperature (9, 12).
required to complete some tests (see Test Method G124).
Relatively little work (1-18) has been done using oxidants
7.6 Flow and Propagation Schemes:
other than oxygen, diluents
...
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.
e1
Designation:G125–95 Designation: G 125 – 00 (Reapproved 2008)
Standard Test Method for
Measuring Liquid and Solid Material Fire Limits in Gaseous
Oxidants
This standard is issued under the fixed designation G 125; 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.
e NOTE—Editorial corrections were made in April 1996.
1. Scope
1.1 This test method covers a procedure for measuring the threshold-limit conditions to allow equilibrium of combustion of
materials in various oxidant gases under specific test conditions of pressure, temperature, flow condition, fire-propagation
directions, and various other geometrical features of common systems.
1.2 This test method is patterned after Test Method D 2863-95 and incorporates its procedure for measuring the limit as a
functionofoxidantconcentrationforthemostcommonlyusedtestconditions.Sections8,9,10,11,13,and14forthebasicoxidant
limit (oxygen index) procedure are quoted directly from Test Method D2863. Oxygen index data reported in accordance with Test
Method D2863 are acceptable substitutes for data collected with this standard under similar conditions. It is anticipated that later
revisions ofTest Method D2863 will yield similarly equivalent results, and as new revisions ofTest Method D2863 are issued, any
changes will beTest Method reviewed for incorporation into this test method. for the basic oxidant limit (oxygen index) procedure
are quoted directly from Test Method D 2863-95. Oxygen index data reported in accordance with Test Method D 2863-95 are
acceptable substitutes for data collected with this standard under similar conditions.
1.3 This test method has been found applicable to testing and ranking various forms of materials. It has also found limited
usefulness for surmising the prospect that materials will prove “oxygen compatible” in actual systems. However, its results do not
necessarily apply to any condition that does not faithfully reproduce the conditions during test. The fire limit is a measurement of
a behavioral property and not a physical property. Uses of these data are addressed in Guides G 63 and G 94.
NOTE 1—Although this test method has been found applicable for testing a range of materials in a range of oxidants with a range of diluents, the
accuracy has not been determined for many of these combinations and conditions of specimen geometry, outside those of the basic procedure as applied
to plastics.
1.4One very specific set of test conditions for measuring the fire limits of metals in oxygen has been codified in Test Method
G124. Test Method G124 measures the minimum pressure limit in oxygen for its own set of test conditions. Its details are not
reproduced in this standard. A substantial database is available for this procedure, although it is much smaller than the database
for Test Method D2863.
NOTE2—Warning:During the course of combustion, gases, vapors, aerosols, fumes or any combination of these are evolved which may be hazardous.
NOTE3—Precaution:Adequate precautions should be taken to protect the operator.
1.5The values stated in SI units are to be regarded as the standard.
1.6 2—Test Method D 2863-95 has been revised and the revised Test Method has been issued as D 2863-97. The major changes
involve sample dimensions, burning criteria and the method for determining the oxygen index. The aim of the revisions was to align
Test Method D 2863 with ISO 4589-2. Six laboratories conducted comparison round robin testing on self-supporting plastics and
cellular materials using D 2863-95 and D 2863-97. The results indicate that there is no difference between the means provided y
the two methods at the 95 % confidence level. No comparison tests were conducted on thin films. The majority of ASTM Committee
G4 favors maintaining the D 2863-95 as the backbone of G 125 until comprehensive comparison data become available.
1.4 One very specific set of test conditions for measuring the fire limits of metals in oxygen has been codified in Test Method
G 124. Test Method G 124 measures the minimum pressure limit in oxygen for its own set of test conditions. Its details are not
reproduced in this standard. A substantial database is available for this procedure, although it is much smaller than the database
for Test Method D 2863-95. (Warning—During the course of combustion, gases, vapors, aerosols, fumes or any combination of
these are evolved which may be hazardous.) (Warning—Adequate precautions should be taken to protect the operator.)
This test method is under the jurisdiction ofASTM Committee G-4G04 on Compatibility and Sensitivity of Materials in Oxygen- EnrichedAtmospheres and is the direct
responsibility of Subcommittee G4.01G04.01 on Test Methods. Portions have been adaptedadopted from Test Method D 2863-95 that is under the jurisdiction of ASTM
Committee D-20D20 on Plastics.
Current edition approved Jan. 15, 1995.April 1, 2008. Published March 1995.July 2008. Originally published as G125–94.approved in 1995. Last previous edition
G125–94.approved in 2000 as G 125 – 00.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
G 125 – 00 (2008)
1.5 The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.
1.6 This basic standard should be used to measure and describe the properties of materials, products, or assemblies in response
to heat and flame under controlled laboratory conditions and should not be used to directly describe or appraise the fire hazard
or fire risk of materials, products or assemblies under actual fire conditions. However, results of this test may be used as elements
of a fire risk assessment which takes into account all of the factors which are pertinent to an assessment of the fire hazard of a
particular end use. The standard has more applicability in this regard at predicting the fire behavior of materials and components
that are close in size to the test condition, than for systems that are much different (for example: comparing a test rod to a valve
seat rather than comparing a test rod to a house or a particle)
1.7 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
2.1 ASTM Standards:
D 618Practice for Conditioning Plastics and Electrical Insulating Materials for Testing Practice for Conditioning Plastics for
Testing
D 1071 Test Methods for Volumetric Measurement of Gaseous Fuel Samples
D 2444 Test Method for Determination of the Impact Resistance ofThermoplastic Pipe and Fittings by Means of aTup (Falling
Weight)
D 2863 Test Method for Measuring the Minimum Oxygen Concentration to Support Candle-Like Combustion of Plastics
(Oxygen Index)
D 2863-95 Test Method for Measuring the Minimum Oxygen Concentration to Support Candle-Like Combustion of Plastics
(Oxygen Index)
D 2863-97 Test Method for Measuring the Minimum Oxygen Concentration to Support Candle-Like Combustion of Plastics
(Oxygen Index)
G 63 Guide for Evaluating Nonmetallic Materials for Oxygen Service
G 94 Guide for Evaluating Metals for Oxygen Service
G 124 Test Method for Determining the Combustion Behavior of Metallic Materials in Oxygen-Enriched Atmospheres
G 128Guide for the Control of Hazards and Risks in Oxygen Systems Guide for Control of Hazards and Risks in Oxygen
Enriched Systems
2.2 Other Standards:
ISO 4589-2 Plastics—Determination of burning behavior by oxygen index—Part 2: Ambient temperature test
3. Terminology
3.1 Definitions:
3.1.1 oxygen compatibility, n—theabilityofasubstancetocoexistwithbothoxygenandapotentialsource(s)ofignitionwithin
the acceptable risk parameter of the user (at an expected pressure and temperature). (See Guide G 128.)
3.1.2 oxygen index, n—the minimum concentration of oxygen, expressed as a volume percent, in a mixture of oxygen and
nitrogen that will just support flaming combustion of a material initially at room temperature under the conditions of Test Method
D 2863. (See Test Method D 2863.)
3.2 Definitions of Terms Specific to This Standard:
3.2.1 fire limit, n—the threshold limit conditions that will just support sustained combustion of a material under a combination
of specified conditions and at least one variable parameter (typically oxidant concentration, diluent nature, pressure, temperature,
geometry, flow or flame parameters, etc.).
3.2.2 oxidant compatibility, n—the ability of a substance to coexist with both an oxidant and a potential source(s) of ignition
within the acceptable risk parameter of the user (at an expected pressure and temperature).
3.2.3 oxidant index, n—the minimum concentration of an oxidant such as oxygen, nitrous oxide, fluorine, etc., expressed as a
volume percent, in a mixture of the oxidant with a diluent such as nitrogen, helium, carbon dioxide, etc., that will just support
sustained combustion of a material initially at given conditions of temperature, pressure, flow conditions, propagation direction,
etc. (See also, oxygen index.)
3.2.3.1 Discussion—The oxidant index may be more specifically identified by naming the oxidant: oxygen limit (or index),
nitrous oxide limit (or index), fluorine limit (or index), etc. Unless specified otherwise, the typical oxidant is taken to be oxygen,
the typical diluent is taken to be nitrogen, and the typical temperature is taken as room temperature.
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
, Vol 08.01.volume information, refer to the standard’s Document Summary page on the ASTM website.
Annual Book of ASTM Standards, Vol 05.05.
Withdrawn.
Annual Book of ASTM Standards, Vol 08.04.ISO 4589-2 First edition 1996-07-15, International Organization for Standardization, Geneve, Switzerland, 1996.
G 125 – 00 (2008)
3.2.4 pressure limit—the minimum pressure of an oxidant (or mixture) that will just support sustained combustion of a material
initially at given conditions of oxidant concentration, temperature, flow condition, propagation direction, etc.
3.2.4.1 Discussion—The pressure limit may be more specifically identified by naming the oxidant: oxygen pressure limit,
nitrous oxide pressure limit, fluorine pressure limit, etc.
3.2.5 temperature limit—the minimum temperature of an oxidant (or mixture) that will just support sustained combustion of a
material initially at given conditions of oxidant concentration, temperature, flow condition, propagation direction, etc.
3.2.5.1 Discussion—The temperature limit may be more specifically identified by naming the oxidant: oxygen temperature
limit, nitrous oxide temperature limit, fluorine temperature limit, etc.
4. Summary of Test Method
4.1 The threshold limit condition (minimum oxidant concentration, minimum pressure, minimum temperature, etc.) that will
just support sustained combustion under equilibrium conditions is measured in a test apparatus. The equilibrium is established by
therelationbetweentheheatgeneratedfromthecombustionofthespecimen(thatmaybeaugmentedbytheheatofdecomposition
of some oxidants) and the heat lost to the surroundings as measured by one or the other of two arbitrary criteria, namely, a time
of burning or a length of specimen burned. This point is approached from both sides of the critical threshold condition in order
to establish the fire limit.
5. Significance and Use
5.1 This test method provides for measuring of the minimum conditions of a range of parameters (concentration of oxidant in
a flowing mixture of oxidant and diluent, pressure, temperature) that will just support sustained propagation of combustion. For
materials that exhibit flaming combustion, this is a flammability limit similar to the lower flammability limit, upper flammability
limit, and minimum oxidant for combustion of gases (1). However, unlike flammability limits for gases, in two-phase systems, the
concept of upper and lower flame limits is not meaningful. However, limits can typically be determined for variations in other
parameters such as the minimum oxidant for combustion (the oxidant index), the pressure limit, the temperature limit, and others.
Measurement and use of these data are analogous to the measurement and use of the corresponding data for gaseous systems.That
is, the limits apply to systems likely to experience complete propagations (equilibrium combustion). Successful ignition and
combustion below the measured limits at other conditions or of a transient nature are not precluded below the threshold.
Flammability limits measured at one set of conditions are not necessarily the lowest thresholds at which combustion can occur.
Therefore direct correlation of these data with the burning characteristics under actual use conditions is not implied.
6. Abstract
6.1 A well-established procedure for measuring an oxidant limit, the oxygen index, of plastics (See Test Method D 2863) is
reviewed, then variations commonly used to collect data for oxidant compatibility purposes are described. In the test, a series of
specimens is placed in a preadjusted oxidant mixture and deliberately ignited. Specimens that do not “burn” are retested in higher
concentrations. Specimens that do burn are retested in lower concentrations. When the operator is confident that the threshold has
been determined by a suitable number and spread of negative tests below the threshold, the lowest positive is reported as the
oxidant index.
6.2 Similartestmethodsapplywhentheoxidantconcentrationisheldconstantandthetemperature,pressureorotherkeyfactor
is varied. In some cases, apparatus modification or replacement is necessary, such as a pressurized vessel is required to complete
some tests (see Test Method G 124). Relatively little work (1-18) has been done using oxidants other than oxygen, diluents other
than nitrogen, pressure, temperature, or other properties as the variable parameter.
7. Variations
7.1 A number of variations of the procedure have been used. The principle variables h
...
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