ASTM E681-09(2023)
Standard Test Method for Concentration Limits of Flammability of Chemicals (Vapors and Gases)

Standard No.

ASTM E681-09(2023)

Release Date

2023

Published By

American Society for Testing and Materials (ASTM)

Latest

ASTM E681-09(2023)

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 (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 Annex A1 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 E2079 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. 1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 8. 1.9 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.

ASTM E681-09(2023) Referenced Document

• ASTM E1445 Standard Terminology Relating to Hazardous Potential of Chemicals
• ASTM E1515 Standard Test Method for Minimum Explosible Concentration of Combustible Dusts
• ASTM E171 Standard Specification for Standard Atmospheres for Conditioning and Testing Flexible Barrier Materials
• ASTM E2079 Standard Test Methods for Limiting Oxygen (Oxidant) Concentration in Gases and Vapors
• ASTM E582 Standard Test Method for Minimum Ignition Energy and Quenching Distance in Gaseous Mixtures

ASTM E681-09(2023) history

• 2023 ASTM E681-09(2023) Standard Test Method for Concentration Limits of Flammability of Chemicals (Vapors and Gases)
• 2009 ASTM E681-09(2015) Standard Test Method for Concentration Limits of Flammability of Chemicals (Vapors and Gases)
• 2009 ASTM E681-09 Standard Test Method for Concentration Limits of Flammability of Chemicals (Vapors and Gases)
• 2004 ASTM E681-04 Standard Test Method for Concentration Limits of Flammability of Chemicals (Vapors and Gases)
• 2001 ASTM E681-01 Standard Test Method for Concentration Limits of Flammability of Chemicals (Vapors and Gases)
• 2001 ASTM E681-98 Standard Test Method for Concentration Limits of Flammability of Chemicals (Vapors and Gases)
• 1985 ASTM E681-85 Standard Test Method for Concentration Limits of Flammability of Chemicals (Vapors and Gases)