Flash point measures the tendency of the specimen to form a flammable mixture with air under controlled laboratory conditions. It is only one of a number of properties that shall be considered in assessing the overall flammability hazard of a material.

Flash point is used in shipping and safety regulations to define flammable and combustible materials. One should consult the particular regulation involved for precise definitions of these classes.

Flash point can indicate the possible presence of highly volatile and flammable materials in a relatively nonvolatile or nonflammable material. For example, an abnormally low flash point on a sample of kerosene can indicate gasoline contamination.

1.1 This test method covers the determination of the flash point, by tag manual and automated closed testers, of liquids with a viscosity below 5.5 mm²/s (cSt) at 40°C (104°F), or below 9.5 mm²/s (cSt) at 25°C (77°F), and a flash point below 93°C (200°F).

1.1.1 For the closed-cup flash point of liquids with the following properties: a viscosity of 5.5 mm²/s (cSt) or more at 40°C (104°F); a viscosity of 9.5 mm²/s (cSt) or more at 25°C (77°F); a flash point of 93°C (200°F) or higher; a tendency to form a surface film under test conditions; or containing suspended solids, Test Method D 93 can be used.

1.1.2 For cut-back asphalts refer to Test Methods D 1310 and D 3143.

Note 1—The U.S. Department of Transportation (RSTA) and U.S. Department of Labor (OSHA) have established that liquids with a flash point under 37.8°C (100°F) are flammable as determined by this test method for those liquids that have a viscosity less than 5.5 mm²/s (cSt) at 40°C (104°F) or 9.5 mm²/s (cSt) or less at 25°C (77°F), or do not contain suspended solids or do not have a tendency to form a surface film while under test. Other flash point classifications have been established by these departments for liquids using this test method.

1.2 This test method can be used to measure and describe the properties of materials, products, or assemblies in response to heat and flame under controlled laboratory conditions and cannot 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 can be used as elements of fire risk assessment that takes into account all of the factors that are pertinent to an assessment of the fire hazard of a particular end use.

1.3 Related Standards are Test Methods D 93, D 1310, D 3828, D 3278, and D 3941.

1.4 The values stated in SI units are to be regarded as standard. The values in parentheses are for information only.

1.5 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. For specific hazard statements see 8.2 and 8.3 and refer to Material Safety Data Sheets.