What is the standard for oxygen index test?

The Oxygen Index (OI) test is a measure of the flammability of materials and their ability to support combustion in the presence of oxygen. The test determines the minimum concentration of oxygen required to sustain flaming combustion of a material under specified test conditions. The standard method for conducting the Oxygen Index test varies depending on the country and industry. In this response, I will provide an overview of two commonly used standards: ASTM D2863 and ISO 4589.

1. ASTM D2863 - Standard Test Method for Measuring the Minimum Oxygen Concentration to Support Candle-Like Combustion of Plastics (Oxygen Index)

ASTM D2863 is a widely accepted international standard for the Oxygen Index test. It is applicable to a wide range of materials, including plastics, elastomers, textiles, and other organic materials.

Key Steps:

a. Specimen Preparation:

   - Cut rectangular specimens of specific dimensions (based on material thickness).

   - Condition the specimens in a controlled environment to reach equilibrium moisture content.

   - Mount the specimen vertically in a glass chimney, leaving a standardized exposed vertical length above the chimney.

b. Test Apparatus:

   - Use a vertical test apparatus consisting of a glass chimney with oxygen and nitrogen flow controllers.

   - Maintain a controlled gas flow rate into the chimney.

c. Test Procedure:

   - Ignite the lower end of the specimen using a pilot flame.

   - Adjust the oxygen concentration supplied to the chimney while observing the behavior of the flame.

   - Determine the minimum oxygen concentration at which the specimen sustains a candle-like flame for a specified duration (usually 3 minutes).

d. Oxygen Index Calculation:

   - Calculate the Oxygen Index as the volume percentage of oxygen required to support combustion.

   - Repeat the test with multiple specimens and calculate the average value.

2. ISO 4589-2 - Plastics - Determination of Burning Behaviour by Oxygen Index - Part 2: Ambient-Temperature Test

ISO 4589-2 is an international standard specifically focused on the Oxygen Index test for plastics.

Key Steps:

a. Specimen Preparation:

   - Prepare rectangular specimens of specific dimensions and thickness.

   - Condition the specimens to reach equilibrium moisture content.

   - Ensure the specimen surface is smooth and free from imperfections.

b. Test Apparatus:

   - Use a vertical test apparatus consisting of a glass chimney with adjustable oxygen and nitrogen flow meters.

c. Test Procedure:

   - Ignite the lower end of the specimen using a pilot flame.

   - Gradually adjust the oxygen concentration supplied to the chimney while observing the behavior of the flame.

   - Determine the minimum oxygen concentration at which the specimen sustains a flame over its full length for a specified duration (usually 60 seconds).

d. Oxygen Index Calculation:

   - Calculate the Oxygen Index as the volume percentage of oxygen required to support combustion.

   - Repeat the test with multiple specimens and calculate the average value.

It's important to note that both ASTM D2863 and ISO 4589 standards provide detailed requirements for test specimens, apparatus setup, safety precautions, and data reporting. Additionally, they may have specific variations or additional test methods based on the material type or specific application requirements. Therefore, it is recommended to refer to the complete standards for accurate and comprehensive testing procedures.