Plastic Resin Flame Rating
At times, we would be asked about a flame rating for the plastic material or compound we either purchase or make here locally. We thought that information was generally lacking or not easily found, so we took the initiative to make it readily available for everyone to learn about.
UL 94 is the flame rating test standard.
“HB” is one classification, and is the most basic. Most plastics will have an HB rating. In fact, we joke that is standards for “happily burning”.
5VA is the highest flame rating a material can have, and indicates the material self extinguishes. Below are all the classifications within the UL94 test:
- HB: slow burning on a horizontal specimen; burning rate < 76 mm/min for thickness < 3 mm or burning stops before 100 mm
- V-2: burning stops within 30 seconds on a vertical specimen; drips of flaming particles are allowed.
- V-1: burning stops within 30 seconds on a vertical specimen; drips of particles allowed as long as they are not inflamed.
- V-0: burning stops within 10 seconds on a vertical specimen; drips of particles allowed as long as they are not inflamed.
- 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.
