For balancing a No. 2 welding tip, how far should the flame blow away from the tip when the acetylene valve is fully open?

For a No. 2 welding tip, a balanced flame is indicated when the flame blows away from the tip approximately 1/4 inch when the acetylene valve is fully open. This specific distance is important because it signifies that the mixture of acetylene and oxygen is optimal for efficient and effective welding. A flame that is balanced at this distance indicates that the gases are mixed correctly, ensuring that the flame doesn't have excessive oxygen or acetylene, which could lead to an unstable flame.

Maintaining the flame at this distance helps prevent issues such as backfire or flashback, which can be dangerous while welding. A properly balanced flame is essential for control and achieving the desired weld quality. While other distances may represent different flame characteristics, 1/4 inch is noted as the standard for proper balancing with a No. 2 tip.