Left hand threads are on all connectors for acetylene gas?

• A. True
• B. False
• C. Usually but not always
• D. Depends on valve type

Answer: (A)

Left-hand threading on acetylene fittings is a safety standard designed to prevent accidental cross-connection with oxygen systems, which use right-hand threads. By making acetylene connectors non-interchangeable with oxygen components, the system reduces the risk of dangerous connections and potential fires or explosions. This standard applies to the cylinder valve outlets, regulators, hoses, and torch fittings, so they mate only with acetylene-specific gear. While some rare or older configurations might differ, the typical practice is that all acetylene connectors use left-hand threads, making the statement true.