TIPS WITH TONY: Flame-Retardant Thermoplastics and UL Classifications

UL 94 is a plastics flammability standard released by the Underwriters Laboratories (USA). The standard classifies plastics according to how they burn in various orientations and part thicknesses from the lowest flame-retardant to most flame-retardant in six different classifications.

UL 94 Rating

Definition of Rating

HB

                                          Slow burning on a horizontal part.

V-2

                                          Burning stops within 30 seconds on a vertical                                             part allowing for drops of flammable plastic.

V-1

                                          Burning stops within 30 seconds on a vertical                                             part allowing for drops of plastic that are not                                               inflames.

V-0

                                          Burning stops within 10 seconds on a vertical                                             part allowing for drops of plastic that are not                                               inflames.

5VB

                                          Burning stops within 60 seconds on a vertical                                             part with no drops of plastic allowed but may                                               burn through the part.

5VA

                                          Burning stops within 60 seconds on a vertical                                             part with no drops of plastic allowed and                                                     cannot burn through the part.

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