5.1 This test method, using a slow rate of heating, provides a uniform temperature throughout the specimen. The slow rate of heating is necessary because of the low thermal conductivity of some liquids such as paints, resins, and related products, and also because of the poor heat transfer by convection in high-viscosity products. Since the specimen is being heated at a reduced rate, the longer time interval between each determination is necessary to reestablish after each flash test the saturation concentration of vapor in the air space above the specimen.

Note 1: ISO 1523 is used in United Nations Recommendations for Transportation of Dangerous Goods and in the International Civil Aviation Organization (ICAO) regulations and for similar regulations in the International Maritime Dangerous Goods (IMDG) code. Test Method D3941, which is similar to ISO 1523, is used in the United States Department of Transportation (USDOT) regulations. The ICAO and IMDG codes are used for transshipment of hazardous materials through the United States to other countries.

1.1 This test method covers the determination of the flash point of liquids in which the specimen and the air/vapor mixture above it are approximately in temperature equilibrium.

1.2 This test method is limited to a temperature range from 0 to 110°C (32 to 230°F).

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

1.4 Warning—Mercury has been designated by many regulatory agencies as a hazardous substance that can cause serious medical issues. Mercury, or its vapor, has been demonstrated to be hazardous to health and corrosive to materials. Use caution when handling mercury and mercury-containing products. See the applicable product Safety Data Sheet (SDS) for additional information. The potential exists that selling mercury or mercury-containing products, or both, is prohibited by local or national law. Users must determine legality of sales in their location.

1.5 This standard is used to measure and describe the response of materials, products, or assemblies to heat and flame under controlled conditions, but does not by itself incorporate all factors required for fire hazard or fire risk assessment of the materials, products, or assemblies under actual fire conditions.

1.6 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.

1.7 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.