ASTM E2079-07
(Test Method)Standard Test Methods for Limiting Oxygen (Oxidant) Concentration in Gases and Vapors
Standard Test Methods for Limiting Oxygen (Oxidant) Concentration in Gases and Vapors
SIGNIFICANCE AND USE
Knowledge of the limiting oxygen (oxidant) concentration is needed for safe operation of some chemical processes. This information may be needed in order to start up or operate a reactor while avoiding the creation of flammable gas compositions therein, or to store or ship materials safely. NFPA 69 provides guidance for the practical use of LOC data, including the appropriate safety margin to use.
Examples of LOC data applications can be found in references (2, 3, 4).
Note 2—The LOC values reported in references (5, 6, and 7), and relied upon by a number of modern safety standards (such as NFPA 69 and NFPA 86) were obtained mostly in a 5-cm diameter flammability tube. This diameter may be too small to mitigate the flame quenching influence impeding accurate determination of the LOC of most fuels. The 4-L minimum volume specified in Section 7 would correspond to a diameter of at least 20 cm. As a result, some LOC values determined using this standard are approximately 1.5 vol.% lower than the previous values measured in the flammability tube, and are more appropriate for use in fire and explosion hazard assessment studies.
Much of the previous literature LOC data (5, 6, 7) were measured in the flammability tube.
SCOPE
1.1 These test methods cover the determination of the limiting oxygen (oxidant) concentration of mixtures of oxygen (oxidant) and inert gases with flammable gases and vapors at a specified initial pressure and initial temperature.
1.2 These test methods may also be used to determine the limiting concentration of oxidizers other than oxygen.
1.3 Differentiation among the different combustion regimes (such as the hot flames, cool flames and exothermic reactions) is beyond the scope of these test methods.
1.4 These test methods 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 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.
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: E2079 − 07
StandardTest Methods for
Limiting Oxygen (Oxidant) Concentration in Gases and
1
Vapors
This standard is issued under the fixed designation E2079; 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.
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1. Scope 2.3 NTIS Publications:
Bulletin 503 Coward, H.F. and Jones, G.W., Bureau of
1.1 These test methods cover the determination of the
Mines, “Limits of Flammability of Gases and Vapors,”
limiting oxygen (oxidant) concentration of mixtures of oxygen
NTIS AD701575, 1952
(oxidant) and inert gases with flammable gases and vapors at a
Bulletin 627 Zabetakis, M.G., Bureau of Mines, “Flamma-
specified initial pressure and initial temperature.
bility Characteristics of Combustible Gases and Vapors,”
1.2 These test methods may also be used to determine the
NTIS AD701576, 1965
limiting concentration of oxidizers other than oxygen.
Bulletin 680 Kuchta, J.M., Bureau of Mines, “Investigation
1.3 Differentiation among the different combustion regimes
of Fire and ExplosionAccidents in the Chemical, Mining,
(such as the hot flames, cool flames and exothermic reactions) and Fuel-Related Industries - A Manual,” NTIS
is beyond the scope of these test methods.
PB87113940, 1985
1.4 These test methods should be used to measure and
3. Terminology
describe the properties of materials, products, or assemblies in
3.1 Definitions:
response to heat and flame under controlled laboratory con-
3.1.1 (see also Terminology E1445):
ditions and should not be used to describe or appraise the fire
3.1.2 flammable—capable of propagating a flame.
hazard or fire risk of materials, products, or assemblies under
actual fire conditions. However, results of this test may be used 3.1.3 ignition—the initiation of combustion.
as elements of a fire risk assessment which takes into account
3.1.4 limit of flammability—the boundary in composition
all of the factors which are pertinent to an assessment of the
space dividing flammable and nonflammable regions.
fire hazard of a particular end use.
3.1.5 limiting oxygen (oxidant) concentration (LOC) of a
1.5 This standard does not purport to address all of the
fuel-oxidant-inert system—the oxygen (oxidant) concentration
safety concerns, if any, associated with its use. It is the
atthelimitofflammabilityfortheworstcase(mostflammable)
responsibility of the user of this standard to establish appro-
fuel concentration.
priate safety and health practices and determine the applica-
3.1.5.1 Discussion—Limiting oxygen (oxidant) concentra-
bility of regulatory limitations prior to use.
tion is also known as minimum oxygen (oxidant) concentration
or as critical oxygen (oxidant) concentration.
2. Referenced Documents
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2.1 ASTM Standards:
4. Summary of Test Method
E1445 Terminology Relating to Hazard Potential of Chemi-
4.1 A mixture containing one or more flammable compo-
cals
nents (fuel), oxygen (oxidant) and inert gas(es) (such as
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2.2 NFPA Publication:
nitrogen, carbon dioxide, argon, etc.) is prepared in a suitable
NFPA 69 Standard on Explosion Prevention Systems
test vessel at a controlled initial temperature and made to the
specified initial pressure. Proportions of the components are
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These test methods are under the jurisdiction of ASTM Committee E27 on
determined by a suitable means. Ignition of the mixture is
Hazard Potential of Chemicals and are the direct responsibility of Subcommittee
E27.04 on Flammability and Ignitability of Chemicals. attempted and flammability is determined from the pressure
Current edition approved Jan. 1, 2007. Published February 2007. Originally
rise produced. The criterion for flammability is a pressure rise
approved in 2000. Last previous edition approved in 2001 as E2079 – 01. DOI:
of≥7 % above the initial absolute test pressure. Fuel, oxygen
10.1520/E2079-07.
2 (oxidant), and inert gas proportions are varied between trials
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
until:
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
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E2079 − 07
NOTE 3—A survey of practitioners of this method indicates that test
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