Are plastics Fire Retardant? – MGS Technical Plastics Blog

The majority of plastic materials used are flammable. However, plastics are used across almost all industry sectors, some of which require products with a degree of flame retardancy.

UL 94

UL 94 is a plastics flammability standard released by the Underwriters Laboratories of the United States. This standard determines the material’s tendency to either extinguish or spread the flame once the specimen has been ignited. This is a standard that is widely accepted around the world.

There are 6 UL94 classifications for the flammability of plastic materials, these are from lowest (Most Flammable) to highest (Least Flammable).

  • 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 are allowed as long as they are not inflamed.
  • V-0 – Burning stops within 10 seconds on a vertical specimen; drips of particles are 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.

Plastic materials can be tested by the Underwriters Laboratories and receive a UL Yellow Card, which is a UL Recognised Component Mark; they can also be tested against these standards in-house by plastic material producers, but this will not result in a Yellow Card being issued.

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