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UL 94
Flammability Tests. The Underwriters Laboratories have developed a serious of flammability tests, all designated under UL 94. For a plastic to receive a certain UL rating, it must pass certain criteria of a test. The different ratings are outlined below
HB
: slow burning on a horizontal specimen; burning rate < 76 mm/min for thickness < 3 mm.
V2
burning stops within 30 seconds on a vertical specimen; drips of flaming particles are allowed.
V1
: burning stops within 30 seconds on a vertical specimen; no drips allowed.
V0
: burning stops within 10 seconds on a vertical specimen; no drips allowed.
5VB
: burning stops within 60 seconds on a vertical specimen; no drips allowed; plaque specimens may develop a hole.
5VA
: burning stops within 60 seconds on a vertical specimen; no drips allowed; plaque specimens may not develop a hole
