What is the maximum safe working gauge pressure for acetylene gas?

• A. 8 psig
• B. 22 psig
• C. 30 psig
• D. 15 psig

Answer: (D)

Acetylene must be used at very low pressures because it can decompose explosively if compressed too much. The maximum safe working gauge pressure for acetylene is 15 psig. This limit is set because acetylene’s stability deteriorates as pressure increases, making higher pressures dangerous for torch work. Regulators are used to keep the output at or below this level, even though the gas in the cylinder is stored at much higher pressures internally. Using a pressure higher than 15 psig significantly raises the risk of an unsafe decomposition or detonation, especially if contaminants are present. The other pressures listed exceed this safe limit or are not the standard upper bound for safe acetylene operation.