This test includes three classifications – 94V-0, 94V-1 and 94V-2 Materials that are thin gauge – typically ? 10 mil, or very flexible may distort, shrink or flex during the 94V test. These materials can be tested using 94VTM – the thin material version of the vertical burning test. This differs in several ways from the 94V test:
The specimen size is 8" x 2").
The specimen is rolled longitudinally around a ?" dia. mandrel and taped on one end. When the mandrel is removed the specimen forms a cone shape, which provides rigidity to the length of the specimen (see Fig. 3.1)
The two flame applications have duration of three seconds instead of ten.
Although this test was designed for thinner gauge materials, any material can be tested using 94VTM as long as can be formed around a ?" mandrel. The test is performed in the same manner as 94V with the above mentioned differences. The Material Classification criteria is also the same as 94V (see Table 1.) except that no specimens shall have flaming or glowing combustion up to a mark 5" from the bottom (free end) of the specimen.
It is usually advantageous to test materials using 94VTM instead of 94V because it is usually easier to pass or get a better rating as long as the material can be bent around the ?" mandrel.
Note: UL will generally accept a 94VTM rating of similar level where a 94V material is required (i.e., 94VTM-0 = 94V-0, 94VTM-1 = 94V-1, etc.). UL does, however, reserve the right to make a determination on which rating a material should have based on the application.