The ASTM D 2863 oxygen index is a test method used to measure the flammability of polymers and other materials in the presence of oxygen. It determines the minimum concentration of oxygen in a mixture with nitrogen that will support combustion of a material. The test measures the oxygen index as a percentage, indicating the minimum oxygen concentration required for the material to sustain combustion.
The oxygen index test is widely used in various industries, including plastics, textiles, and automotive, to assess the fire safety properties of materials. It provides valuable information about the material's resistance to ignition and its ability to self-extinguish when exposed to a flame.
During the test, a sample of the material is placed vertically in a combustion chamber. The chamber is then filled with a mixture of oxygen and nitrogen gases. The oxygen concentration is gradually reduced by replacing it with nitrogen until the material stops burning. The oxygen index is determined by the lowest oxygen concentration at which the material continues to burn for a specified duration.
The ASTM D 2863 standard provides guidelines for conducting the oxygen index test. It specifies the test apparatus, sample dimensions, and testing conditions to ensure consistent and reliable results. The test results can be used to compare the flammability characteristics of different materials or to evaluate the effectiveness of flame-retardant additives.
The oxygen index value obtained from the test is an important parameter for material selection and design considerations. Materials with higher oxygen index values are generally considered more flame-resistant and less likely to support combustion. They have a greater ability to resist ignition and self-extinguish, making them suitable for applications where fire safety is a concern.
It is important to note that the oxygen index test provides information about a material's flammability in the presence of oxygen but does not assess its behavior in other fire scenarios, such as in the absence of oxygen or under specific heat flux conditions. Therefore, it should be used in conjunction with other fire testing methods to comprehensively evaluate the fire performance of materials.
In summary, the ASTM D 2863 oxygen index is a test method used to measure the flammability of materials by determining the minimum concentration of oxygen required for combustion. It is a valuable tool for assessing the fire safety properties of polymers and other materials and plays a crucial role in material selection and design for various industries.