Flame retardant grade refers to the property that the substance or material has after treatment to significantly delay the spread of flame, and is divided into a grade system based on this.
The flame retardant grade of plastics increases gradually from HB, V-2 and V-1 to V-0:
1. HB: the lowest flame retardant grade in UL94 standard. For samples 3 to 13 mm thick, the combustion rate is required to be less than 40 mm per minute; For samples less than 3 mm thick, the combustion rate is less than 70 mm per minute; Or go out in front of the 100mm mark.
2. V-2: after two 10 second combustion tests on the sample, the flame goes out within 60 seconds. There can be combustibles falling.
3. V-1: after two 10 second combustion tests on the sample, the flame goes out within 60 seconds. No combustibles can fall.
4. V-0: after two 10 second combustion tests on the sample, the flame goes out within 30 seconds. No combustibles can fall.
