A fusible plug is made from

A fusible plug is made from

• A. A polymer
• B. A ceramic
• C. A metal alloy that will burn when overheated
• D. Pure gold

Answer: (C)

Fusible plugs rely on a metal alloy with a deliberately low melting point to fail safely if the boiler overheats. When the heat climbs and water protection is lost, the alloy melts at its designed temperature, allowing steam to escape and preventing an explosion. That capability—the controlled melting of a low-melting-point metal alloy—is what makes a fusible plug effective. Other materials wouldn’t serve this function: polymers would burn or degrade, ceramics wouldn’t melt at the right temperature to relieve pressure, and pure gold has a complex, much higher melting point that wouldn’t trigger at the safe overheating threshold.

Fusible plugs rely on a metal alloy with a deliberately low melting point to fail safely if the boiler overheats. When the heat climbs and water protection is lost, the alloy melts at its designed temperature, allowing steam to escape and preventing an explosion. That capability—the controlled melting of a low-melting-point metal alloy—is what makes a fusible plug effective. Other materials wouldn’t serve this function: polymers would burn or degrade, ceramics wouldn’t melt at the right temperature to relieve pressure, and pure gold has a complex, much higher melting point that wouldn’t trigger at the safe overheating threshold.