The main difference between the vertical and horizontal burn tests lies in the orientation of the specimen during the testing process and the specific aspects they evaluate. Here's a breakdown of the key differences:
1. Orientation:
- Vertical Burn Test: The specimen is mounted vertically and exposed to a vertically upward flame. The flame is applied to the lower end of the specimen.
- Horizontal Burn Test: The specimen is mounted horizontally and exposed to a horizontally directed flame. The flame is applied to the starting point of the specimen.
2. Flame Propagation:
- Vertical Burn Test: This test assesses the material's resistance to vertical burning. It measures factors such as the material's ability to self-extinguish and the rate of vertical flame propagation.
- Horizontal Burn Test: This test evaluates the material's tendency to propagate fire across its surface when exposed to a horizontal flame.
3. Dripping Behavior:
- Vertical Burn Test: This test examines if the material drips flaming particles or particles that ignite flammable materials below the specimen.
- Horizontal Burn Test: This test does not specifically evaluate dripping behavior.
4. Standard Classification:
- Vertical Burn Test: The results of the vertical burn test are classified based on several factors such as burn rate, afterglow time, dripping behavior, and ignition of cotton located beneath the specimen. The classification ranges from V-0 (best) to V-2 (lowest).
- Horizontal Burn Test: The results of the horizontal burn test are primarily classified based on flame propagation, burning duration, and dripping behavior. The classification ranges from V-0 (best) to V-2 (lowest).
In summary, the vertical burn test assesses the material's resistance to vertical burning and dripping behavior, while the horizontal burn test evaluates flame propagation, burning duration, and dripping behavior when exposed to a horizontal flame. Both tests provide valuable insights into a material's flammability characteristics, but they focus on different aspects and orientations of combustion.