Standard for Flammable Plastics UL 94

UL 94 Flammability Standard for Plastics

UL 94 is a safety standard that evaluates the flammability of plastic materials used in industries and consumer products. UL 94 tests determine whether a plastic material will self-extinguish after ignition or continue to burn.

Flammability classification of plastics according to UL 94:

1. Standard Plastics

• HB (Horizontal Burning) – Slowly burning material in a horizontal position. If it self-extinguishes before reaching 100 mm, it meets this classification.
• V-2 – Burning stops within 30 seconds (vertically positioned sample). Dripping of flaming plastic is allowed.
• V-1 – Burning stops within 30 seconds, dripping is allowed only if it does not ignite.
• V-0 – Burning stops within 10 seconds, dripping is allowed only if it does not ignite.
• 5VB – Burning stops within 60 seconds, no dripping is allowed. The material may be penetrated but not fully burned through.
• 5VA – Burning stops within 60 seconds, no dripping is allowed. The material must not be penetrated.

2. Foam and Layered Plastics

• HF-2 – Burning stops within 3 seconds, glowing ceases within 30 seconds. Dripping of flaming plastic is allowed.
• HF-1 – Burning stops within 2 seconds, glowing ceases within 30 seconds. Dripping of flaming plastic is not allowed.

Testing of Plastic Materials

UL 94 tests are conducted on samples measuring 12.7 × 1.27 cm with a minimum allowed thickness. For 5VA and 5VB classifications, testing is performed both on the material sample and the final product.

Practical Applications of UL 94 Classification

Plastics tested according to UL 94 are used in electronics, household appliances, the automotive industry, and other fields where fire resistance is crucial. For general household use, including kitchen plastics, materials with a higher non-flammability rating, such as V-0 or 5VA, are preferred.