GB/T 8924-2026Test method for the flammability characteristics of fibre reinforced plastics - Oxygen index method (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 replaces GB/T 8924-2005 "Test Method for Combustion Performance of Fiber Reinforced Plastics - Oxygen Index Method", and is consistent with GB/T 8924- Compared to.2005, aside from structural adjustments and editorial changes, the main technical changes are as follows:

a) The scope of applicable materials has been changed (see Chapter 1, Chapter 1 of the.2005 edition);

b) The requirements for gas control and measurement devices have been changed (see 5.4,

5.1.3 of the.2005 edition);

c) The sample quantity requirements have been changed (see 6.3,.2005 version 6.3);

d) Requirements for markings and burning distances have been added (see

e) The method for obtaining results has been changed (see 7.10,

7.7.1 of the.2005 edition, and Appendix A);

f) The step size requirements have been changed (see

7.10.2.3 and 7.10.2.4, A.2.13.2 and A.2.13.3 of the.2005 edition);

g) The calculation of the oxygen index has been changed (see Chapter 8, Chapter 8 in the.2005 edition);

h) The representation of the test results has been changed (see Chapter 9, Chapter 9 of the.2005 edition). 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 by the China Building Materials Federation. This document is under the jurisdiction of the National Technical Committee on Standardization of Fiber Reinforced Plastics (SAC/TC39). This document was drafted by: Luoyang Shipbuilding Materials Research Institute (725th Research Institute of China Shipbuilding Group Corporation) and China Classification Society Shanghai Branch. Standards Research Institute, Shandong Non-metallic Materials Research Institute, Sichuan Fire Research Institute of the Ministry of Emergency Management, and Taistek (Suzhou) Testing Instruments Technology Co., Ltd. The company, Modis Combustion Technology (Suzhou) Co., Ltd., and Beijing Fiberglass Research and Design Institute Co., Ltd. The main drafters of this document are. Li Xiang, Wang Fangling, Yao Haiying, Wang Qianqian, Zhu Jian, Wang Wei, Chen Junhui, Wang Zhandong, Ji Bing, and Hu Changfei. Wu Yanpeng, Sun Yan, Li Xili, Zhang Xiaomei, Fan Yuting, Wang Haiyang. This document was first published in 1988, revised for the first time in.2005, and this is the second revision. Test methods for the combustion performance of fiber-reinforced plastics Oxygen Index Method

1.Scope This document specifies the principle, test apparatus, specimen, test procedure, result calculation, and test results for the oxygen index test of fiber-reinforced plastics. Test report. This document applies to the determination of the oxygen index of fiber-reinforced plastics, but not to the evaluation of materials that exhibit high shrinkage rates after heating.

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.

GB/T 1446 General Rules for Test Methods of Properties of Fiber Reinforced Plastics

GB/T 3863 Industrial Oxygen

GB/T 3864 Industrial Nitrogen

3.Terms and Definitions The following terms and definitions apply to this document.

3.1 oxygen index The minimum oxygen concentration required to maintain material combustion in a nitrogen and oxygen mixture at (23±2)°C, expressed as a volume fraction.

4.Principles The sample is vertically fixed in the combustion chamber. An oxygen-nitrogen mixture flows upwards through the sample, igniting the top of the sample. Timing and observation of the combustion process are performed simultaneously. The burning length was compared with the prescribed criteria. A group of samples were tested in different oxygen concentrations, and the maximum burning length at which the sample could just maintain stable combustion was determined. The oxygen concentration is expressed as the volume fraction of oxygen in the gas mixture.

5 Experimental Apparatus

5.1 General Rules A schematic diagram of an oxygen index meter is shown in Figure 1, and it should include at least the components specified in

5.2 Combustion Tube Heat-resistant glass with an inner diameter of 75mm~100mm, a height of 450mm~500mm, and an inner diameter of 40mm at the outlet of the top flow restrictor cover. The tube is vertically fixed to a base through which oxygen and nitrogen mixed gas flows. The bottom is filled with glass beads with a diameter of 3mm to 5mm, to a height of The diameter is 80mm to 100mm. A metal mesh is placed above the glass beads to prevent falling combustion debris from blocking the gas inlet and gas distribution passage.

5.3 Sample holder A component capable of being fixed at the center of the combustion cylinder shaft and vertically clamping the sample. The contours of the sample clamp and its support should be smooth to facilitate the application of the sample. Minimize the turbulence of the incoming gas.

6 Samples

6.1 Sample Preparation Prepare the test specimens according to the relevant provisions of GB/T 1446.

6.2 Sample Size The sample length is 70mm~150mm, the width is (6.5±0.5)mm, and the thickness is (3.00±0.25)mm. Samples of other thicknesses are also available. Experiments can be conducted, but the results can only be compared at the same thickness.

6.3 Number of Samples Each group of samples shall contain no fewer than 15 specimens.

6.4 Appearance Requirements The appearance of the test specimen shall comply with the relevant provisions of GB/T 1446.

6.5 Conditioning and Test Environment Conditioning and testing environment shall be carried out in accordance with the relevant provisions of GB/T 1446.

7 Experimental Procedure

7.1 Specimen Measurement and Marking Measure the sample dimensions, with the thickness accurate to

0.01 mm, and draw a mark 50 mm from the ignition end of the sample.

7.2 Equipment Inspection Before the test, the valve should be turned to check for air leaks at the connection.

7.3 Determination of oxygen concentration at the start of the experiment Estimate the oxygen concentration at the start of the test based on experience or the ignition characteristics of the sample in air. If it ignites rapidly in air, then begin the test. The oxygen concentration is approximately 18% when the flame is burning slowly or intermittently in air; it is approximately 21% when the flame is burning slowly or intermittently in air; and it extinguishes immediately upon removal of the ignition source in air. At least 25%.

7.4 Install the test specimen Clamp the sample onto the fixture and install it vertically at the center of the combustion chamber, ensuring that the top of the sample is at least [amount missing] below the top of the combustion chamber. The lowest point of the exposed part of the sample should be at least 100 mm above the bottom of the combustion chamber.

7.5 Regulating Gas Control Device The combustion chamber is washed for at least 30 seconds with a determined oxygen concentration and a gas flow rate of (40±2) mm/s.

9 Test Results

9.1 Oxygen concentration values and results records for each sample.

9.2 Oxygen index, rounded to one decimal place, cannot be rounded.

10 Test Report The test report should include the following.

a) Specify whether this document and method A or B are used;

b) Identification characteristics of the material. name, serial number, batch number, manufacturer, etc.;

c) Sample size and conditioning conditions;

d) Type of ignition gas;

e) Oxygen index;

f) Combustion characteristics (if any);

g) Test environment, date, and test personnel;

h) Other matters that need to be noted.