UL 94 20-mm vertical burning test

Examples of Small Heat Source Ignition Tests 14.2.2.1 UL 94 20-mm Vertical Burning Test... 

The results of the UL 94 20-mm vertical burning test are very sensitive to the exact duration of flame application and to the technique that is used to apply and remove the flame.19 The magnitude of the effect depends on the type of material that is being tested. Loosely following the test procedure might result in an unwarranted V-0 classification. 

FIGURE 14.3 UL 94 20-mm vertical burning test (dimensions in millimeters). 

The UL 94 standard specihes bench-scale test methods to determine the acceptability of plastic materials for use in appliances or other devices with respect to flammability under controlled laboratory conditions. The test method that is used depends on the intended end-use of the material and its orientation in the device. The standard outlines two horizontal burning tests, three vertical burning tests, and a radiant panel flame spread test. The most commonly used test method described in the UL 94 standard is the 20-mm Vertical Burning Test V-0, V-l, or V-2. The method is also described in ASTM D 3801. A schematic of the test setup is shown in Figure 14.3. 

This test is more stringent than UL 94 V-0, V-1, and V-2. Here, 127 mm ignition flame is applied on specimen bars of dimensions 127 x 12.7 nun, with maximum thickness 12.7 mm. In Method A, a Tirril burner is positioned 20 from the vertical and the overall height of the flame is adjusted to 127 mm. The flame is applied for 5 s and removed for 5 s. The procedure is repeated five times. After the fifth removal of the flame, the duration of flaming and glowing, the distance the specimen burned, the... 

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