What do the UL ratings mean?

Surface Burn

Vertical Burn

Horizontal Burn

Doesn’t ignite under hotter flame

Self extinguishing

Slow burn rating

UL 94 5VA

UL 94 5VB

UL 94 V0 (best)

UL 94 V1 (good)

UL 94 V2 (drips)

UL 94 HB

(Takes more than

3 min. to burn 4”)

 

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.

Article Title:
What do the UL ratings mean?
Article Summary:
UL 94 Flammability Ratings Summary
Article Date:
11/16/2010
Article ID:
881
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