Oil must never be used around a ______ cylinder.

Oil must never be used around a ______ cylinder.

• A. Oxygen
• B. Helium
• C. Nitrogen
• D. Acetylene

Answer: (D)

Oil around acetylene is dangerous because acetylene is highly unstable and can decompose explosively in the presence of oil or grease. Even a small amount of oil in contact with an acetylene cylinder, regulator, or fittings can trigger a violent reaction, especially under pressure or heat. That’s why all equipment used with acetylene must be completely oil-free and clean. Helium and nitrogen are inert to oil, and while oil around oxygen cylinders also poses a serious fire risk, the specific hazard cited here is acetylene’s tendency to ignite or explode when contaminated with oil.

Oil around acetylene is dangerous because acetylene is highly unstable and can decompose explosively in the presence of oil or grease. Even a small amount of oil in contact with an acetylene cylinder, regulator, or fittings can trigger a violent reaction, especially under pressure or heat. That’s why all equipment used with acetylene must be completely oil-free and clean. Helium and nitrogen are inert to oil, and while oil around oxygen cylinders also poses a serious fire risk, the specific hazard cited here is acetylene’s tendency to ignite or explode when contaminated with oil.