In solid fuel boilers, what mechanism extinguishes the fire if the water level is low?

In solid fuel boilers, what mechanism extinguishes the fire if the water level is low?

• A. Fusible Plug
• B. Safety Valve
• C. Thermocouple
• D. Grate

Answer: (A)

When water is sufficient, the firebox is cooled by the surrounding water. If the water level drops and the crown sheet overheats, a fusible plug—made of a metal with a low melting point—melts. This creates a passage that allows boiler water to flood into the firebox, rapidly cooling the hot metal and extinguishing the flame. The plug acts as a passive safety device to prevent overheating and potential failure. The other mechanisms listed don’t automatically flood the furnace with water to quench the fire: a safety valve only relieves pressure, a thermocouple senses temperature, and a grate is just part of the fuel bed.

When water is sufficient, the firebox is cooled by the surrounding water. If the water level drops and the crown sheet overheats, a fusible plug—made of a metal with a low melting point—melts. This creates a passage that allows boiler water to flood into the firebox, rapidly cooling the hot metal and extinguishing the flame. The plug acts as a passive safety device to prevent overheating and potential failure. The other mechanisms listed don’t automatically flood the furnace with water to quench the fire: a safety valve only relieves pressure, a thermocouple senses temperature, and a grate is just part of the fuel bed.