Question 20Motor Plants - QMED

The correct answer is B) warn the engineer of low water level. Fusible plugs are safety devices installed in fire-tube boilers. They are designed to melt at a predetermined temperature, which is typically lower than the temperature that would cause damage to the boiler. When the water level in the boiler drops to a dangerously low level, the exposed crown sheet heats up, causing the fusible plug to melt. This triggers an alarm or automatically shuts down the boiler, warning the engineer of the low water condition and preventing further damage to the boiler. The other options are incorrect because: A) Draining the boiler is not the primary purpose of fusible plugs. C) Cooling the crown sheet is not the function of fusible plugs. D) Fusible plugs do not open the burners' electrical firing circuits; they are a separate safety mechanism.