Preliminary Screening of Plastics for Fire Performance

UL 94 (Underwriters Laboratories test standard UL 94) is one of the most widely used flammability tests for determining relative flammability for plastic materials. It measures the ability of plastic part to extinguish the flame after ignition and its dripping behavior in response to a small open flame or radiant heat source under controlled laboratory conditions.

 

The tests results are intended to serve as a preliminary indication of the material’s suitability with respect to flammability for a particular application, such as plastic materials used for parts in electronic devices and appliances.

 

The flammability is influenced by several factors such as:

Ease of ignition – how rapidly a material ignites

Flame spread – how rapidly fire spreads across a polymer surface

Fire endurance – how rapidly fire penetrates a wall or barrier

Rate of heat release – how much heat is released and how quickly

Ease of extinction – how rapidly the flame chemistry leads to extinction

Smoke evolution

Toxic gas generation

 

Hence, the study of how plastics burn has been, and continues to be, a major area of research to examine:

The nature of the burning phenomenon in plastics

Various methods to reduce plastics flammability, and

Methods to test flammability