What are the classifications of plastic flame retardant?

There are 12 kinds of plastic flame retardant grades in UL94: HB, V-0, V-1, V-2, 5VA, 5VB, VTM-0, VTM-1, VTM-2, HBF, HF-1, HF- 2.

　　 Flammability UL94 grade is a widely used plastic material flammability performance standard. It is used to evaluate the ability of a material to extinguish after being ignited. According to the burning speed, burning time, anti-drip ability and whether the drops are burning, there are many ways to judge. Many values can be obtained for each tested material according to color or thickness. When the material of a certain product is selected, its UL rating should meet the thickness requirements of the wall part of the plastic part. The UL rating should be reported together with the thickness value. It is not enough to report the UL rating without the thickness.

　　 The flame retardant grades of plastics are gradually increased from HB, V-2, V-1, V-0, 5VB to 5VA:

　　HB: The lower flame retardant grade in the UL94 standard. It is required that for samples with a thickness of 3 to 13 mm, the burning rate is less than 40 mm per minute; for samples with a thickness of less than 3 mm, the burning rate is less than 70 mm per minute; or extinguished before the 100 mm mark.

　　V-2: After two 10-second combustion tests on the sample, the residual flame extinguished within 60 seconds. The dripping particles can ignite cotton.

　　V-1: After two 10-second combustion tests on the sample, the residual flame extinguished within 60 seconds. The dripping particles cannot ignite the cotton.

　　V-0: After two 10-second burning tests on the sample, the residual flame extinguished within 30 seconds. The dripping particles cannot ignite the cotton.

　　5VB: After five seconds of burning test on the sample, the residual flame will be extinguished within 60 seconds. The dripping particles cannot ignite the cotton. For block samples, it is allowed to be burned through.

　　5VA: After five seconds of burning test on the sample, the residual flame will be extinguished within 30 seconds. The dripping particles cannot ignite the cotton. For block samples, it is not allowed to be burned through.