The LOI (Limiting Oxygen Index) value of plastics and compounds used in industry is specific and can be measured using an LOI test device.
The LOI test, in general terms, defines the maximum percentage of oxygen a material can be exposed to before combustion. A material with a low LOI value (e.g., standard air containing 21% oxygen) ignites and burns with a match flame, whereas a high LOI value describes the material’s resistance to fire.
The LOI device measures the oxygen level at the point where nitrogen and oxygen gases are supplied to the device chamber, and it regulates the gases by adjusting their levels. The sample placed in the holder inside the device chamber is ignited with a Bunsen burner flame to test whether it ignites at the specified oxygen percentage.
At Kabkom Chemistry laboratory, the FireMaster brand LOI test device is used to routinely verify the fire resistance performance of the produced cable compounds. Additionally, it is utilized for new product development studies and comparative sample analyses, enriching the laboratory’s expertise. The tests are conducted in accordance with ISO 4589 and ASTM D 2863 Standards.
Samples, cut to dimensions of 3 mm *,6.5 mm* 70 mm, are placed in the device’s sample holder and exposed to a flame for 5 seconds at the adjusted oxygen percentage. The sample is considered to have passed the test if it doesn’t burn for 180 seconds or over a length of 50 mm, and the test is continued by increasing the oxygen percentage. The highest oxygen level reached until either 180 s. or 50 mm of burning is the measured LOI value of the sample. This value is substituted into the equation provided in the standard and added to the constants. If statistically validated, the measurement confirms the LOI value of the product.
