ISO 9038:2025
(Main)Determination of sustained combustibility of liquids
Determination of sustained combustibility of liquids
This document specifies a procedure, at temperatures up to 100 °C, to determine whether a liquid product, that would be classified as “flammable” by virtue of its flash point, sustains combustion at the temperature(s) specified, for example, in regulations. NOTE Many national and international regulations classify liquids as presenting a flammable hazard based on their flash point, as determined by a recognized method. Some of these regulations allow a derogation if the substance cannot “sustain combustion” at some specified temperature(s). The procedure is applicable to paints (including water-borne paints), varnishes, paint binders, solvents, petroleum or related products and adhesives, that have a flash point. It is not applicable to painted surfaces in respect of assessing their potential fire hazards. This test method is applicable, in addition to test methods for flash point, for assessing the fire hazard of a product.
Essai de détermination de la combustion entretenue de liquides
Le présent document spécifie un mode opératoire, applicable jusqu'à 100 °C, qui vise à déterminer si un produit liquide, qui serait classé comme «inflammable» du fait de son point d'éclair, entretient une combustion à la température ou aux températures spécifiées, par ex. dans les règlements. NOTE De nombreux règlements nationaux et internationaux classent les liquides présentant un risque d'inflammabilité sur la base de leur point d'éclair, déterminé par une méthode reconnue. Certains de ces règlements autorisent une dérogation si la substance en question ne peut pas «entretenir la combustion» à une ou plusieurs températures spécifiées. Cette méthode est applicable aux peintures (y compris peintures en phase aqueuse), vernis, liants, solvants, produits pétroliers ou apparentés et adhésifs, qui ont un point d'éclair. Elle n'est pas applicable aux surfaces peintes, eu égard à l'évaluation du danger d'incendie qu'elles présentent. Cette méthode d'essai est applicable, en complément de celles qui portent sur le point d'éclair, à l'évaluation du danger d'incendie d'un produit.
General Information
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Standards Content (Sample)
International
Standard
ISO 9038
Fourth edition
Determination of sustained
2025-02
combustibility of liquids
Essai de détermination de la combustion entretenue de liquides
Reference number
© ISO 2025
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus . 2
6 Preparation of apparatus and verification . 3
7 Sampling . 3
7.1 Paints, varnishes and related products .3
7.2 Petroleum and related products .3
7.2.1 Sampling procedure .3
7.2.2 Sample handling .3
8 Procedure . 4
9 A ssessment of results . 5
10 Calculation of the adjusted test temperature . 6
11 Precision . 6
12 Test report . 6
Annex A (normative) Combustibility tester. 7
Annex B (normative) Apparatus verification . .10
Bibliography .11
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 28, Petroleum and related products, fuels
and lubricants from natural or synthetic sources, in collaboration with the European Committee for
Standardization (CEN) Technical Committee CEN/TC 139, Paints and varnishes, in accordance with the
Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This fourth edition cancels and replaces the third edition (ISO 9038:2021), which has been technically
revised.
The main changes are as follows:
— 8.6 and 8.7 have been revised; Warnings have been added in 8.6 to give improved advice to the operator
on possible ignition and burning scenarios that can be met during the test.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
A product with a flash point within a given range can continue to burn after initial ignition, while a similar
product, although it has a similar flash point, does not continue to burn. This document describes a method
for discriminating between those products that sustain combustion and those that do not.
The method determines whether a flammable product, when maintained at a selected test temperature,
generates sufficient flammable vapour to cause ignition when an ignition source is applied and then
continues to generate sufficient vapour to burn when the ignition source is moved to the “off” position.
This test method does not determine the flash point of the product under test but, by means of a test
procedure, merely determines if it sustains combustion at a selected test temperature; this criterion can
be required to comply with laws or regulations relating to the storage, transport and use of flammable
products. Before performing this test, for safety and test optimization reasons, it is usual to determine either
the actual flash point of the material or know the temperature range in which the flash point is located.
The apparatus specified in this document enables a result to be determined by a rapid procedure using a
small test portion (2 ml).
v
International Standard ISO 9038:2025(en)
Determination of sustained combustibility of liquids
WARNING — The use of this document can involve hazardous materials, operations and equipment.
This document does not purport to address all of the safety problems associated with its use. It is
the responsibility of users of this document to take appropriate measures to ensure the safety and
health of personnel prior to the application of this document, and to determine the applicability of
any other restrictions for this purpose.
1 Scope
This document specifies a procedure, at temperatures up to 100 °C, to determine whether a liquid product,
that would be classified as “flammable” by virtue of its flash point, sustains combustion at the temperature(s)
specified, for example, in regulations.
NOTE Many national and international regulations classify liquids as presenting a flammable hazard based on
their flash point, as determined by a recognized method. Some of these regulations allow a derogation if the substance
cannot “sustain combustion” at some specified temperature(s).
The procedure is applicable to paints (including water-borne paints), varnishes, paint binders, solvents,
petroleum or related products and adhesives, that have a flash point. It is not applicable to painted surfaces
in respect of assessing their potential fire hazards.
This test method is applicable, in addition to test methods for flash point, for assessing the fire hazard of a
product.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) 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 terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
sustained combustibility
behaviour of a material, under specified test conditions, whereby its vapour can be ignited by an ignition
source and, after ignition, sufficient flammable vapour is produced for burning to continue for at least 15 s
after the source of ignition has been removed
3.2
flash point
lowest temperature of the test portion, adjusted to account for variations in atmospheric pressure from
101,3 kPa, at which application of an ignition source causes the vapour of the test portion to ignite and the
flame to propagate across the surface of the liquid under the specified conditions of test
4 Principle
A test portion of specified volume is introduced into a test cup, which is maintained at the test temperature.
After a specified time, an ignition source is applied.
[2]
In connection with the United Nations recommendations on the Transport of Dangerous Goods as well as
[1]
with the Globally Harmonized System of Classification and Labelling of Chemicals, and also with derived
national/EC regulations, temperatures of 60,5 °C and 75,0 °C are specified for this test.
The property of the product to sustain combustion is assessed based on the ignition of its vapours or
components, when exposed to an ignition source, and whether it continues to burn after the ignition source
has been moved to the “off” position. The “off” and “test” positions of the ignitor are shown in Figure A.1.
5 Apparatus
5.1 Combustibility tester, as specified in Annex A.
5.2 Electrical heater, attached to the bottom of the test cup in a manner that provides efficient transfer
of heat. The heater control shall be capable of maintaining the test cup temperature, as measured on the
temperature measuring device, and in a draught-free area, within ± 0,5 °C for test temperatures ≤ 100 °C.
The combustibility tester, heater and heater control unit may consist of an integrated apparatus.
5.3 Gauge, for checking that the height of the centre of the gas jet above the top of the test cup is
2,2 mm ± 0,1 mm. A calibrated metal strip is suitable.
5.4 Temperature measuring device, suitable for horizontal operation, and of
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