What safety device is used on an acetylene cylinder?

• A. Fusible plug
• B. Pressure safety disc
• C. Spring-loaded plug
• D. Check valve

Answer: (A)

When an acetylene cylinder is exposed to heat, the protective device is a fusible plug. This plug is made of a metal that melts at a set, relatively low temperature. If the cylinder gets hot, the plug melts and creates an opening that releases gas, relieving pressure and helping prevent a catastrophic rupture or explosion. This design is specifically suited to acetylene because of the danger of overheating and the need for a controlled venting response.

A pressure safety disc (rupture disc) is a different type of venting mechanism used on other high‑pressure systems, but it isn’t the standard safety device in acetylene cylinders. A spring‑loaded plug or a check valve serves other roles—neither provides the thermal-activation venting protection that the fusible plug offers.