What is the oxygen index test?

The oxygen concentration value is called the oxygen index (OI) or historically called the limiting oxygen index (LOI). Use a paramagnetic oxygen analyzer to measure the oxygen concentration and control by changing the relative flow of oxygen and nitrogen through the vertical glass column. The sample is supported vertically in the glass column, and then the fire source is placed in contact with the top edge of the sample and taken out.

 

If "ignition" occurs (such as the standard defines different types of materials), the oxygen concentration in the column of the next sample will decrease. If the ignition is not successful, the oxygen concentration of the next sample will increase. This systematic approach continues until the lowest oxygen concentration is determined to support the combustion of the material.

 

The lower the limiting oxygen index, the greater the possibility of the material catching fire and burning. For example, materials with a determined oxygen index of less than 20.9% will continue to burn in the normal atmosphere after the ignition source is removed.

Definition of oxygen index:

 

When a mixture of oxygen and nitrogen at 23°C±2°C is introduced, only the minimum oxygen concentration that keeps the material burning is expressed in volume fraction.

 

EN ISO 4589-2 test principle:

 

Fix the sample vertically in a transparent combustion tube with a mixed gas of oxygen and nitrogen flowing upwards, ignite the top of the sample, observe the combustion characteristics of the sample, and compare the continuous burning time or length of the sample with the given standard. The minimum oxygen concentration of a series of samples with different oxygen concentrations.

 

EN ISO 4589-2 oxygen index test data requirements:

 

Different risk levels have different requirements for oxygen index test data

 

EN ISO 4589-2 oxygen index test sample size requirements:

 

150mm*6.5mm*3mm

 

Or 140mm * 52mm * thickness

 

 

The above is the information about oxygen index definition introduced by Shanghai Standard Group. If you want to know more information, please leave us a message: http://www.standard-groups.com/en/