ISO 9038-2021 Liquid Delay Flammability Tests

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This document has been prepared by the Technical Committee ISO/TC 28, Petroleum and related Products, fuels and lubricants from natural or synthetic sources, in cooperation with the Technical Committee CEN/TC 139, Paints and varnishes of the European Committee for Standardization (CEN), in accordance with the Technical Cooperation Agreement between ISO and CEN (Vienna Agreement).

The third edition cancelled and replaced the technically revised second edition (ISO 9038:2013).

The main changes from the previous edition are as follows:

– The test method conforms to the requirements of UN test L.2[1][2]. Special:

– Specifies the requirement for triplicate testing rather than duplicate testing;

— Standard test temperature has been changed to 60,5 °C;

— The standard for sustained combustion was revised.

Any feedback or questions about this document should be directed to the user’s national standards body. A complete list of these institutions can be found at

ISO 9038-2021 Liquid Delay Flammability Tests

Products with flash points within a given range may continue to burn after initial ignition, while similar products will not continue to burn despite having similar flash points. This document describes a method for distinguishing between products that sustain combustion and those that do not.

This method determines whether the flammable product produces enough flammable vapor to cause ignition while held at the selected test temperature, and then continues to produce enough vapor to burn when the ignition source moves to the “off” position.

The test method does not determine the flash point of the product under test, but only determines whether it remains burning at the selected test temperature through the test procedure; The standard may be required to comply with laws or regulations relating to the storage, transportation and use of flammable products. Prior to performing this test, the actual flash point of the material is usually determined or the temperature range in which the flash point is located is known for safety and test optimization reasons.

The device specified in this document is able to determine the results by using the quick procedure in the small Test section (2ml).

Caution The use of this document may involve hazardous materials, operations, and equipment. This document is not intended to address all security concerns associated with its use. It is the responsibility of the user of this document to take appropriate steps to ensure the safety and health of personnel before applying this document and to determine whether any other restrictions apply for this purpose.

1 range
This document sets out procedures for determining at temperatures up to 100°C whether liquid products classified as “flammable” because of their flash point continue to burn at the temperatures specified in the regulations.

Note that many national and international regulations classify liquids as flammable hazards based on their flash point, as determined by accepted methods. Some of these regulations allow for “sustained combustion” of substances at certain temperatures.

This procedure applies to paints (including water-based paints), varnishes, paint adhesives, solvents, petroleum or related products and adhesives that have flash points. It is not suitable for painted surfaces whose potential fire hazards are assessed.

In addition to the flash point test method, this test method is also suitable for assessing the fire risk of products.

ISO 9038-2021 Liquid Delay Flammability Tests

2 Normative references
The following files are referenced in the text in such a way that some or all of the content constitutes the requirements of this document. For dated references, citation-only versions apply. For undated references, the new version of the reference (including any revisions) applies.

ISO 1513, Paints and varnishes – Examination and preparation of test samples

ISO 3170, petroleum liquids — Manual sampling

ISO 3171, Petroleum liquids – Automatic pipeline sampling

ISO 15528, Paints, varnishes and raw materials for paints and varnishes – Sampling

3 Terms and Definitions

For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain databases of terms for standardization at the following addresses:

– ISO online browsing platform:

— IEC electronic encyclopedia: available at

3.1 Continuous flammability
The behavior of a material under specified test conditions in which its vapor can be ignited by an ignition source and, after ignition, produce enough flammable vapor to continue burning for at least 15 seconds after the ignition source is removed

3.2 Flash Point
The minimum temperature of the test section, adjusted for a change in atmospheric pressure of 101,3 kPa, at which the application of an ignition source will cause the steam in the test section to ignite and the flame to spread across the liquid surface under the specified test conditions

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