What is UL 94 method of flammability test?

UL94 is a flammability testing standard used to evaluate the combustion characteristics of plastic materials. This test standard is formulated by Underwriters Laboratories, UL in the United States, and it is one of the standards widely used in the world.

The UL94 test method divides plastic materials into different grades based on their burning properties. The following are the general steps of the UL94 test method:

1.Sample preparation:

Cut the plastic material to be tested into the specified size and shape, and clean it to ensure that there is no dirt or grease on the surface.

2. Combustion test: 

Place the sample in a vertical combustion tester and ignite its lower end. According to the combustion characteristics of the sample, it is divided into the following grades:

V-0 level: stop burning within 10 seconds, no dripping

V-1 level: stop burning within 30 seconds, no dripping

Level V-2: Stops burning within 30 seconds, dripping may occur

HB level: After the test, there may still be burn marks on the sample, but they will not extend along the surface of the sample.

3. Drop test: 

For V-2 grade samples, a drop test is also required. Place the sample in a vertical flame tester, ignite its lower end, and observe for drips. If there is no dripping, the sample meets the V-2 level requirements.

The UL94 test method is a standardized flammability test method that can be used to evaluate the combustion characteristics of plastic materials and determine whether they meet specific safety standards and regulatory requirements.