Product Principle and Function:
Definition of oxygen index and its principle for evaluating the relative flammability of polymer materials;
Understand the structure and working principle of XWR-2406 oxygen index apparatus;
Master the basic method of using XWR-2406 oxygen index apparatus to determine the oxygen index of common materials;
Evaluate the combustion performance of common materials.
When a substance burns, it consumes a large amount of oxygen. Different combustible materials require different amounts of oxygen for combustion. By measuring the low oxygen consumption during the combustion process of a substance, the oxygen index value of the substance can be calculated, which can evaluate the combustion performance of the substance. The so-called oxygen index refers to the minimum oxygen concentration required for a specimen to maintain stable combustion (i.e., flaming combustion) in an oxygen-nitrogen mixed gas flow under specified test conditions, expressed as the volume percentage of oxygen (i.e., the minimum volume percentage concentration of oxygen in the oxygen-nitrogen mixed gas required to sustain combustion for 50mm length or 3 minutes after the specimen is ignited). It is very effective in judging the difficulty of combustion when a material contacts flame in air.
Generally, materials with OI<27 are considered flammable, those with 27≤OI<32 are combustible, and those with OI≥32 are flame-retardant. The ZR-2406 oxygen index apparatus is used to determine the volume percentage of oxygen required during the combustion of a substance.
The testing method for oxygen index is to vertically clamp a specimen of certain dimensions in a transparent combustion cylinder with a specimen holder, where an upward flowing oxygen-nitrogen gas mixture is supplied in a certain proportion. Ignite the top of the specimen, observe the subsequent combustion phenomenon, and record the duration of sustained combustion or the distance burned. If the combustion time exceeds 3 minutes or the flame front exceeds the 50mm mark, reduce the oxygen concentration; if the combustion time is less than 3 minutes or the flame front does not reach the mark, increase the oxygen concentration. Repeat this operation, gradually approaching the specified value from both upper and lower sides, until the concentration difference between the two is less than 0.5%.
Reference standard: GB/T2406-1993 "Plastics - Determination of flammability by oxygen index".
