Oxygen index methods describe the tendency of a material to sustain a flame. The most important feature of these methods is that a sample is burned in a controlled atmosphere. The standard method is to ignite the top of the sample using a gas flame drawn when ignition occurs and find the lowest oxygen concentration in the upward-flowing oxygen and nitrogen mixture that supports sustained combustion.
The limited oxygen index (LOI), also known as the critical oxygen index or the oxygen index, is defined as the minimum amount of oxygen in a mixture of oxygen and nitrogen to support combustion only after ignition. The tests are carried out under standard conditions, at a temperature of 25 degrees. The current standard method for limited oxygen index (LOI) determinations specifies a linear flow rate of 4 plus/minus 1 cm/sec.
The limited oxygen index test is considered one of the most useful flammability tests as it allows for numerically precise grading of materials and simplifies the selection of thermoplastics for flammability. Limited oxygen index testing overcomes the serious disadvantages of conventional flammability testing.
One standard on which these tests are based is: ASTM D2863-19 The standard test method for measuring the minimum oxygen concentration (oxygen index) to promote wax burning of plastics. This fire-test-response standard describes a test method for measuring the minimum concentration of oxygen, expressed as percent by volume, that will support flaming combustion in a flowing mixture of oxygen and nitrogen. This test method provides three test procedures:
The test methods described allow testing of structurally self-supporting materials in the form of vertical bars or sheets up to 10.5 mm thick. Such materials are solid, layered or cellular materials characterized by an apparent density greater than 15 kg/m3. These test methods also allow testing flexible sheet or film materials while being supported vertically.
Our organization, among the numerous test, measurement, analysis and evaluation studies it provides for businesses in various sectors, also provides services for the determination of oxygen index and combustion characteristics with its trained and expert staff and advanced technological equipment.
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