The UL94 flame retardant testing method is used to assess the flammability of plastics in manufacturing equipment and appliances. It is commonly employed for products with specific flammability requirements, providing fundamental indicators of important characteristics such as ignitability, burning rate, flame spread, fuel contribution, combustion intensity, and combustion products. The UL-94 test method (as established by Underwriters Laboratories) is widely utilized for evaluating the combustibility of plastic materials used in electrical and electronic devices.
Figure 1: UL94 Flammability Test for V0, V1, V2 Levels
Figure 2: Horizontal Burning Test for HB Level
Figure 3: Vertical Burning Test for 5VA and 5VB Levels
Testing procedures vary based on different flame retardancy levels:
- HB Level: A sample is exposed to a flame at a horizontal angle; if it burns longer than specified times or drops flaming debris after contact with the flame.
- V0/V1/V2 Levels: Samples are subjected to vertical flames under defined conditions including time until ignition occurs and burn duration measurements.
Each level has specific criteria regarding maximum allowable burning times and whether any flaming debris ignites cotton placed below the sample during tests.
