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What do the UL ratings mean?

Surface BurnVertical BurnHorizontal Burn
Doesn’t ignite under hotter flameSelf extinguishingSlow burn rating
UL 94 5VAUL 94 V0 (best)UL 94 HB
UL 94 5VBUL 94 V1 (good)(Takes more than 3 min. to burn 4")
UL 94 V2 (drips)
5VA
Surface Burn		Burning stops within 60 seconds after five applications of five seconds each of a flame (larger than that used in Vertical Burn testing) to a test bar. Test specimens MAY NOT have a burn- though (no-hole). This is the highest (most flame retardant) UL94 rating.
5VB
Surface Burn		Burning stop within 60 seconds after five applications of five seconds each of a flame (larger than that used in Vertical Burn testing) to a test bar. Test specimens MAY HAVE a burn through (a hole).
V-0
Vertical Burn		Burning stops within 10 seconds after two applications of ten seconds each of a flame to a test bar. NO flaming drips are allowed.
V-1
Vertical Burn		Burning stops within 60 seconds after two applications of ten seconds each of a flame to a test bar. NO flaming drips are allowed.
V-2
Vertical Burn		Burning stops within 60 seconds after two applications of ten seconds each of a flame to a test bar. Flaming drips ARE allowed.
H-B
Horizontal Burn		Slow horizontal burning on a 3mm thick specimen with a burning rate is less than 3"/min or stops burning before the 5" mark. H-B rated materials are considered "self-extinguishing". This is the lowest (least flame retardant) UL94 rating.
Title: What do the UL ratings mean?
Description: UL 94 Flammability Ratings Summary
Published: 11/16/2010
Last Edited: 1/20/2023

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