Types of testing/flammability ratings covered in the UL 94 standard for flammability of plastic materials include: 

Vertical burning tests (V-0, V-1, V-2, 5V, 5VA, 5VB, VTM-0, VTM-1, and VTM-2); and 

Horizontal burning tests (HB, HBF, HF-1, HF-2). 

The UL test methods are aligned with IEC 60707, IEC 60695-11- 10, IEC 60695-11-20, ISO 9772, and ISO 9773 standards used to determine fire properties. 

Vertical Burning Test for Classifying Materials 

UL 94 V Rating: V-0, V-1, V-2 — This test measures the self-extinguishing time of the vertically oriented polymer specimen. The top of the test specimen is clamped to a stand, and the burner is placed directly below the specimen. The test evaluates both the burning and afterglow times and dripping of the burning test specimen. 

The material will be rated: 

V-0: if flame extinguishes within 10 seconds with no dripping; 

V1: if flame extinguishes within 30 seconds with no dripping; and 

V2: if flame extinguishes within 10 seconds with dripping. 

UL 94 VTM Rating: VTM-0, VTM-1, and VTM-2 - Thin Material Vertical Burning Testing 

This test method is used for thin specimen or materials that are too flexible or may distort, shrink, or flex during the traditional vertical testing (failure to pass the UL 94 V test is a precondition of all VTM ratings). This test is similar to the vertical burning test except that the material is wrapped around a mandrel before clamping to the stand and the flame application is reduced. In this test, the flame is applied only for 3 seconds.