Judge the flame retardancy of fabrics are usually two basis:
One is to judge from the combustion rate of fabric to. After finishing of fabrics according to the provisions of a flame for a certain time, and then move the flame, determination of fabric to continue flaming and smoldering, and fabrics is the scaleof the damage. Flaming and smoldering time is shorter, lower by the scale of the damage, said the flame retardancy of fabrics as possible; otherwise, it means thatthe poor performance of fire retardant fabrics.
Another is to judge from the determination of the limiting oxygen index of the sample. Limiting oxygen index (LOI) refers to the quantity of oxygen required for combustion of the sample, so by measuring the oxygen index to determine the flame retardancy of fabrics. Oxygen index higher then the higher the concentration of oxygen needed to sustain combustion, which means more difficult to burn. Samples that are available in the index in oxygen and nitrogen mixed gas of oxygen needed tokeep the candle burning in the smallest size expressed as a percentage. Theoretically, oxygen index of textile materials if greater than 21% (nature, volume concentration of oxygen in the air), it is self-extinguishing in the air. According to the size of the oxygen index, usually textiles into flammable (LOI<20%), flammable (LOI=20%~26%), flame (LOI=26%~34%) and non-combustible (LOI>35%) four levels.