How many turns should acetylene valves be opened?

Acetylene valves should be opened one and a half turns to ensure proper operation. This opening allows for sufficient gas flow while still ensuring that the valve can be shut off easily in case of an emergency. The one and a half turns approach balances the need for adequate gas supply with the safety risks associated with acetylene, which is highly flammable.

If the valve were opened only one full turn, it might restrict the gas flow and hamper the efficiency of the equipment that is using acetylene. Conversely, opening the valve too much, such as two or more turns, could pose a risk of excessive gas flow, which could lead to dangerous situations, such as creating a potential for gas leaks or combustion hazards.

Thus, the one and a half turns is the most appropriate method for ensuring both functionality and safety when working with acetylene valves in any application.