What are the conditions of the oxygen index test?

 

1. Test samples: The test samples are typically rectangular strips of the material being tested, with a specified length and width. The thickness of the sample is also specified based on the type of material being tested. Multiple samples may be tested to determine an average OI value.

 

2. Test apparatus: The test apparatus consists of a combustion chamber, a gas supply system, and a system for measuring the concentration of oxygen in the gas mixture. The combustion chamber is typically made of glass or other transparent material and is fitted with a burner at one end.

3. Gas mixture: The gas mixture used in the test is typically a blend of oxygen and nitrogen, with the proportion of oxygen gradually decreased in successive tests until the material fails to ignite or sustain combustion.

 

4. Test procedure: The test procedure involves suspending the sample vertically in the combustion chamber and gradually decreasing the proportion of oxygen in the gas mixture until the material no longer supports combustion. The oxygen index is then calculated as the minimum concentration of oxygen required to support combustion, expressed as a percentage.

 

5. Test conditions: The test conditions, including the size and orientation of the sample, the rate of gas flow, and the temperature and humidity of the testing environment, may be specified by the test standard being followed.

 

It is important to follow the specific test standard being used and to carefully control the test conditions to ensure accurate and reliable test results.