ASTM E681-04
(Test Method)Standard Test Method for Concentration Limits of Flammability of Chemicals (Vapors and Gases)
Standard Test Method for Concentration Limits of Flammability of Chemicals (Vapors and Gases)
SIGNIFICANCE AND USE
The LFL and UFL of gases and vapors define the range of flammable concentrations in air.
Limits of flammability may be used to determine guidelines for the safe handling of volatile chemicals. They are used particularly in assessing ventilation requirements for the handling of gases and vapors. NFPA 69provides guidance for the practical use of flammability limit data, including the appropriate safety margins to use.
Note 2—For hydrocarbons, the break point between nonflammability and flammability occurs over a narrow concentration range at the lower flammability limit, but the break point is less distinct at the upper limit. For materials found to be non-reproducible per 13.1.1 that are likely to have large quenching distances and may be difficult to ignite, such as ammonia and certain halogenated hydrocarbon, the lower and upper limits of these materials may both be less distinct. That is, a wider range exists between flammable and nonflammable concentrations (see Annex A1).
Note 3—This method measures the LFL and UFL for upward (and partially outward) flame propagation. the limits for downward flame propagation are narrower.
SCOPE
1.1 This test method covers the determination of the lower and upper concentration limits of flammability of chemicals having sufficient vapor pressure to form flammable mixtures in air at atmospheric pressure at the test temperature. This test method may be used to determine these limits in the presence of inert dilution gases. No oxidant stronger than air should be used.
Note 1—The lower flammability limit and upper flammability limit are also referred to as the lower explosive limit (LEL) and the upper explosive limit (UEL), respectively.
1.2 This test method is based on electrical ignition and visual observations of flame propagation. Users may experience problems if the flames are difficult to observe (for example, irregular propagation or insufficient luminescence in the visible spectrum), if the test material requires large ignition energy, or if the material has large quenching distances.
1.3 provides a modified test method for materials (such as certain amines, halogenated materials, and the like) with large quenching distances which may be difficult to ignite.
1.4 In other situations where strong ignition sources (such as direct flame ignition) is considered credible, the use of a test method employing higher energy ignition source in a sufficiently large pressure chamber (analogous, for example, to the methods in Test Method E 2079 for measuring limiting oxygen concentration) may be more appropriate. In this case, expert advice may be necessary.
1.5 The flammability limits depend on the test temperature and pressure. This test method is limited to an initial pressure of the local ambient or less, with a practical lower pressure limit of approximately 13 kPa (100 mm Hg). The maximum practical operating temperature of this equipment is approximately 150°C (302°F).
1.6 The values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for information only.
1.7 This test method 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 method may be used as elements of a fire risk assessment that takes into account all of the factors pertinent to an assessment of the fire hazard of a particular end use.
1.8 This standard may involve hazardous materials, operations, and equipment. 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 regul...
General Information
Relations
Buy Standard
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
Designation: E681 – 04
Standard Test Method for
Concentration Limits of Flammability of Chemicals (Vapors
1
and Gases)
This standard is issued under the fixed designation E681; 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 1.6 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are provided for
1.1 This test method covers the determination of the lower
information only.
and upper concentration limits of flammability of chemicals
1.7 Thistestmethodshouldbeusedtomeasureanddescribe
having sufficient vapor pressure to form flammable mixtures in
the properties of materials, products, or assemblies in response
air at atmospheric pressure at the test temperature. This test
to heat and flame under controlled laboratory conditions and
method may be used to determine these limits in the presence
shouldnotbeusedtodescribeorappraisethefirehazardorfire
of inert dilution gases. No oxidant stronger than air should be
risk of materials, products, or assemblies under actual fire
used.
conditions.However,resultsofthistestmethodmaybeusedas
NOTE 1—The lower flammability limit (LFL) and upper flammability
elements of a fire risk assessment that takes into account all of
limit (UFL) are sometimes referred to as the lower explosive limit (LEL)
the factors pertinent to an assessment of the fire hazard of a
and the upper explosive limit (UEL), respectively. However, since the
particular end use.
terms LEL and UEL are also used to denote concentrations other than the
1.8 This standard may involve hazardous materials, opera-
limitsdefinedinthistestmethod,onemustexaminethedefinitionsclosely
tions, and equipment. This standard does not purport to
when LEL and UEL values are reported or used.
address all of the safety concerns, if any, associated with its
1.2 This test method is based on electrical ignition and
use. It is the responsibility of the user of this standard to
visual observations of flame propagation. Users may experi-
establish appropriate safety and health practices and deter-
ence problems if the flames are difficult to observe (for
mine the applicability of regulatory limitations prior to use.
example, irregular propagation or insufficient luminescence in
Specific precautionary statements are given in Section 8
the visible spectrum), if the test material requires large ignition
energy, or if the material has large quenching distances.
2. Referenced Documents
1.3 AnnexA1 provides a modified test method for materials
2
2.1 ASTM Standards:
(such as certain amines, halogenated materials, and the like)
E171 Specification for Atmospheres for Conditioning and
withlargequenchingdistanceswhichmaybedifficulttoignite.
Testing Flexible Barrier Materials
1.4 In other situations where strong ignition sources (such
E582 Test Method for Minimum Ignition Energy and
as direct flame ignition) is considered credible, the use of a test
Quenching Distance in Gaseous Mixtures
method employing higher energy ignition source in a suffi-
E1445 Terminology Relating to Hazard Potential of Chemi-
ciently large pressure chamber (analogous, for example, to the
cals
methods in Test Method E2079 for measuring limiting oxygen
E1515 Test Method for Minimum Explosible Concentration
concentration) may be more appropriate. In this case, expert
of Combustible Dusts
advice may be necessary.
E2079 Test Methods for Limiting Oxygen (Oxidant) Con-
1.5 The flammability limits depend on the test temperature
centration in Gases and Vapors
and pressure. This test method is limited to an initial pressure
2.2 NFPA Standard:
of the local ambient or less, with a practical lower pressure
3
NFPA 69 Standard on Explosion Prevention Systems
limit of approximately 13 kPa (100 mm Hg). The maximum
practical operating temperature of this equipment is approxi-
3. Terminology
mately 150°C (302°F).
3.1 Definitions:
1 2
This test method is under the jurisdiction ofASTM Committee E27 on Hazard For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Potential of Chemicals and is the direct responsibility of Subcommittee E27.04 on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Flammability and Ignitability of Chemicals. Standards volume information, refer to the standard’s Document Summary page on
CurrenteditionapprovedJune1,2004.PublishedJuly2004.Originallyapproved the ASTM website.
3
in1979.Lastpreviouseditionapprovedin2001asE681–01.DOI:10.1520/E0681- Available from National Fire Protection Association, Batterymarch Park,
04. Quincy, MA 02269.
Copyright © ASTM International, 100 Barr Harbor Drive
...
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:E681–01 Designation: E 681 – 04
Standard Test Method for
Concentration Limits of Flammability of Chemicals (Vapors
1
and Gases)
This standard is issued under the fixed designation E 681; 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 determination of the lower and upper concentration limits of flammability of chemicals having
sufficient vapor pressure to form flammable mixtures in air at atmospheric pressure at the test temperature. This test method may
be used to determine these limits in the presence of inert dilution gases. No oxidant stronger than air should be used.
NOTE1—The lower flammability limit and upper flammability limit are also referred to as the lower explosive limit (LEL) and the upper explosive limit
(UEL), respectively. 1—The lower flammability limit (LFL) and upper flammability limit (UFL) are sometimes referred to as the lower explosive limit
(LEL) and the upper explosive limit (UEL), respectively. However, since the terms LEL and UEL are also used to denote concentrations other than the
limits defined in this test method, one must examine the definitions closely when LEL and UEL values are reported or used.
1.2 This test method is based on electrical ignition and visual observations of flame propagation. Users may experience
problems if the flames are difficult to observe (for example, irregular propagation or insufficient luminescence in the visible
spectrum), if the test material requires large ignition energy, or if the material has large quenching distances.
1.3 AnnexA1 provides a modified test method for materials (such as certain amines, halogenated materials, and the like) with
large quenching distances which may be difficult to ignite.
1.4 In other situations where strong ignition sources (such as direct flame ignition) is considered credible, the use of a test
method employing higher energy ignition source in a sufficiently large pressure chamber (analogous, for example, to the methods
in Test Method E 2079 for measuring limiting oxygen concentration) may be more appropriate. In this case, expert advice may be
necessary.
1.5 The flammability limits depend on the test temperature and pressure.This test method is limited to an initial pressure of the
local ambient or less, with a practical lower pressure limit of approximately 13 kPa (100 mm Hg). The maximum practical
operating temperature of this equipment is approximately 150°C (302°F).
1.6 ThevaluesstatedinSIunitsaretoberegardedasthestandard.Thevaluesgiveninparenthesesareprovidedforinformation
only.
1.7 This test method 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 method may be used as elements
of a fire risk assessment that takes into account all of the factors pertinent to an assessment of the fire hazard of a particular end
use.
1.8 This standard may involve hazardous materials, operations, and equipment. 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.Specificprecautionarystatements
are given in Section 8
2. Referenced Documents
2
2.1 ASTM Standards:
E 171 Specification for Standard Atmospheres for Conditioning and Testing Flexible Barrier Materials
E 582 Test Method for Minimum Ignition Energy and Quenching Distance in Gaseous Mixtures
E 1445 Terminology Relating to Hazardous Potential of Chemicals
E 1515 Test Method for Minimum Explosible Concentration of Combustible Dusts
1
This test method is under the jurisdiction of ASTM Committee E27 on Hazard Potential of Chemicals and is the direct responsibility of Subcommittee E27.04 on
Flammability and Ignitability of Chemicals.
Current edition approved Oct. 10, 2001. Published February 2002. Originally published as E681 – 79. Last previous edition E681 – 98.
Current edition approved June 1, 2004. Published July 2004. Originally approved in 1979. Last
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.