How far should the acetylene cylinder valve be opened for welding and cutting?

Opening the acetylene cylinder valve for welding and cutting to a range of 1/4 to 1/2 turn is appropriate because it ensures sufficient gas flow while maintaining safety. This specific range allows for a controlled release of acetylene, which is crucial for creating the desired flame characteristics in welding and cutting operations.

If the valve is opened too little, there may not be enough gas to create the proper oxidizing environment, which can lead to incomplete burning and inefficient welding or cutting. On the other hand, opening the valve too much could create a hazardous situation, as acetylene is flammable and can lead to excessive pressure buildup in the system.

This specific opening range balances the need for ample gas flow with the need to prevent pressure-related hazards. Keeping it within this limit enhances safety while still providing enough fuel for effective operations.