GB/T 21790-2025Determination of flash point - Method for flash no-flash and flash point by small scale closed cup tester (English PDF)

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part 1: Structure and Drafting Rules of Standardization Documents".

Drafting.

This document supersedes GB/T 21790-2008 "Determination of Flashfire and Non-Flashfire - Rapid Equilibrium Closed Cup Method" and is consistent with GB/T 21790-2008.

Aside from structural adjustments and editorial changes, the main technical changes are as follows.

---The scope has been changed (see Chapter 1, Chapter 1 of the 2008 edition);

---Added terms and definitions for "equilibrium," "fatty acid methyl esters," "flash point," and "non-equilibrium" (see Chapter 3);

---Added procedure B for rapid equilibrium flash point determination and procedure C for non-equilibrium flash point determination (see Chapters 4 and 8);

---Added low-temperature environment procedures A and B for manual instruments (see Appendix D).

This document is equivalent to ISO 3679:2022 "Determination of flash point - Small closed cup test apparatus for the determination of flash point of flammable and non-flammable materials".

method".

Please note that some content in this document may involve patents. The issuing organization of this document assumes no responsibility for identifying patents.

This document was proposed and is under the jurisdiction of the National Technical Committee on Standardization of Hazardous Chemicals Management (SAC/TC251).

Introduction

This document includes three procedures (A, B, and C), which relate to the determination of flash ignition and flash point, respectively. The rapid equilibration procedure A and rapid equilibration...

Balanced procedure B can determine flash ignition and flash point separately. Non-balanced procedure C uses automatic test cup temperature control to determine flash point.

GB/T 21792 and GB/T 21775 are also closed-cup equilibrium test methods, which can be considered when selecting a method.

Compared with the requirements in GB/T 21792 or GB/T 21775, the instruments specified in this document can use a faster procedure A or B and smaller sample sizes (2 mL or 4 mL) yielded similar test results. Furthermore, the instrument described in this document is portable and can be used in the field.

The tests can also be routinely used in the laboratory. Collaborative work has shown that the results obtained by these methods are comparable.

When using this method to test mixtures containing halogenated hydrocarbon solvents, unusual results may be obtained, and the interpretation of these results should be approached with caution.

In addition, some studies have shown that the flash point of certain water-based paints can be overestimated when using an electric igniter.

Flash point is used as a classification attribute in transportation, storage, handling, and safety regulations to define "flammable" and "combustible" materials. Each specific flash point...

The regulations for each category provide precise definitions.

Flash point indicates the presence of highly volatile substances in relatively non-volatile or non-flammable materials. Flash point testing is commonly used to determine the composition of unknown materials.

Preliminary steps to conduct further investigations.

This method is not suitable for testing the flash point of potentially unstable, easily decomposed, or explosive substances. That is, unless the required temperature for this method has been determined beforehand, it is not suitable.

Within a certain temperature range, heating a specified number of test samples in contact with the metal parts of the flash point apparatus will not cause decomposition, explosion, or other adverse effects.

The flash point value is not a constant representing a physicochemical property of the substance being tested. It is influenced by the design of the instrument, the conditions under which it is used, and the specific procedure performed.

The operating procedures are closely related. Therefore, flash point can only be defined according to one standard test method, and different test methods or methods using different test procedures may not be valid.

The results obtained from the testing instruments showed no universally valid correlation between them.

Flash point determination using a small closed-cup tester Methods for determining flashover, non-flashover, and flash point Warning. Use of this document may involve hazardous materials, operations, and equipment. This document is not intended to address all safety concerns associated with its use.

The user of this document is responsible for taking appropriate measures to ensure the safety and health of personnel before applying this document and to determine whether any issues exist.

Under any other restrictions.

1 Scope

This document describes three procedures (A, B, and C) for flashover, non-flashover, and flash point determination, specifying the principles, reagents, and materials for each procedure.

Materials, instruments, samples, test procedures, test data processing, result expression, precision and test reports.

Procedures A and B in this document apply to paints (including water-based paints), varnishes, paint bases for paints and varnishes, adhesives, solvents, and stone.

Oil products (including aviation turbine fuel), diesel and kerosene fuels, fatty acid methyl esters and related products, with a temperature range of -30°C to 300°C.

Flashover, non-flashover, and flash point tests are performed. Procedures A and B in this document are respectively used to determine whether a product will flash over at a specified temperature.

(Flash-out and non-flash-out procedure A) and flash point of the sample (procedure B). This document also applies to the determination of fatty acid methyl esters when using a flash point detector.

(FAME) flash point.

Program C in this document is applicable to petroleum products (including aviation turbine fuel), diesel, and kerosene with flash points ranging from -20°C to 300°C.

Fuels and petroleum-related products. Their precision is determined within the temperature range of 40°C to 135°C.

2 Normative references

The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are not included.

For references to documents, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies.

This document.

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Note. GB/T 20777-2006 Examination and preparation of test specimens for paints and varnishes (ISO 1513:1992, IDT) ISO 3170 Petroleum liquids - Manual sampling Note. GB/T 4756-2015 Manual Sampling Method for Petroleum Liquids (ISO 3170:2004, MOD) Note. GB/T 27867-2011 Automatic Sampling Method for Petroleum Liquids Pipelines (ISO 3171:1988, IDT) ISO 15528 Paints, varnishes and paints and varnishes - Sampling of raw materials for use in drawing materials Note. GB/T 3186-2006 Sampling of raw materials for paints, varnishes and paints and varnishes (ISO 15528:2000, IDT) Note. GB/T 15000.7-2021 Guidelines for the Work of Standard Samples Part 7: General Requirements for the Competence of Standard Sample Producers (ISO 17034:2016) IDT) ISO 33405 Methods for describing and evaluating the homogeneity and stability of standard specimens (Reference materials - Approaches for