Final answer:
The statement about the acetylene valve being opened no more than one and one-half turns is True. This is a safety measure to control the gas flow and prevent accidents when using an oxyacetylene torch.
Step-by-step explanation:
The statement that the acetylene valve should never be opened more than one and one-half turns when using an oxyacetylene torch is True. This safety guideline is important to prevent the rapid release of gas that could cause an unsafe condition or potentially lead to an accident.
The general practice when operating welding equipment is to open the valve slowly and only as much as is necessary to maintain control over the gas flow.
When dealing with gases under pressure, it's crucial to follow proper procedures. The instruction relates to the safety practices one must follow, ensuring that the correct amount of acetylene gas is used during welding, and to avoid overpressure or accidents. It is essential to operate valves correctly for safe handling of pressurized flammable gases like acetylene.