Flameretardant grade refers to the property that the substance or material has aftertreatment to significantly delay the spread of flame, and is divided into agrade system based on this.

Theflame retardant grade of plastics increases gradually from HB, V-2 and V-1 toV-0:

1.HB: the lowest flame retardant grade in UL94 standard. For samples 3 to 13 mmthick, the combustion rate is required to be less than 40 mm per minute; Forsamples less than 3 mm thick, the combustion rate is less than 70 mm perminute; Or go out in front of the 100mm mark.

2.V-2: after two 10 second combustion tests on the sample, the flame goes outwithin 60 seconds. There can be combustibles falling.

3.V-1: after two 10 second combustion tests on the sample, the flame goes outwithin 60 seconds. No combustibles can fall.

4.V-0: after two 10 second combustion tests on the sample, the flame goes outwithin 30 seconds. No combustibles can fall.