UL-94 Vertical & Horizontal Flame Test is a plastics flammability standard released by Underwriters Laboratories of the USA. The UL-94 standard classifies plastics according to how they burn in various orientations and thicknesses.
From lowest to highest, the grades are:
|Horizontal Flame Tests|
|UL-94-HB||slow burning on a horizontal specimen; burning rate < 76 mm/min for thickness < 3 mm and burning stops before 100 mm|
|Vertical Flame Tests|
|UL-94-V2||burning stops within 30 seconds on a vertical specimen; drips of flaming particles are allowed.|
|UL-94-V1||burning stops within 30 seconds on a vertical specimen; drips of particles allowed as long as they are not inflamed.|
|UL-94-V0||burning stops within 10 seconds on a vertical specimen; drips of particles not allowed.|
|UL-94-5VB||burning stops within 60 seconds on a vertical specimen; no drips allowed; plaque specimens may develop a hole.|
|UL-94-5VA||burning stops within 60 seconds on a vertical specimen; no drips allowed; plaque specimens may not develop a hole|
For 5VA and 5VB ratings, tests are performed on both bar and plaque specimens, and the flame ignition source is approximately five times as severe as that used for testing the other materials.
There are other classifications that apply to low density foam materials (HF-1, HF-2, HBF) and thin films (VTM-0, VTM-1, VTM-2).
ITRI Innovation’s UK laboratory is extremely experienced at providing UL-94 results, with a fast turnaround, at very competitive rates.