UL 1581 is an American standard (Standard for Safety for Electrical Wires, Cables, and Flexible Cords - Test Methods for Electrical Insulation Materials). The standard contains several test methods, including the Vertical Burn Test, which is used to evaluate the burning characteristics of wire and cable insulation materials.
In UL 1581, the specific method of vertical burning test is called vertical burning test (VW-1), also known as UL 1581 test method 1500. This test method involves hanging a sample of wire or cable vertically and exposing it to a flame. Then, observe the burning speed of the wire or cable under the action of the flame, the burning time and the dripping after burning to determine whether it meets the specific safety standard.
The requirements for vertical burn tests in UL 1581 include provisions for test equipment and test procedures, as well as requirements for test samples. Specifically, the test equipment must meet certain specifications, such as flame height, combustion chamber size, and temperature. Test procedures include preconditioning, testing and evaluation, and must be carried out under specific environmental conditions, such as room temperature and humidity. The requirements for test samples include specifications in terms of size, shape and quantity.
In the vertical burning test, the safety standard of the UL 1581 standard requires that the wire or cable have sufficient fire resistance under certain burning conditions to avoid the occurrence of fire or slow down the spread of fire. Specifically, the tested wire or cable cannot be completely burned within a certain period of time, cannot produce excessive smoke and toxic gases, and cannot drip during combustion. If the test sample meets these requirements, it complies with the vertical burn test requirements of the UL 1581 standard.