Fusible Plug

The function of fusible plug is to extinguish the fire in the fire box, when water level in the boiler comes down the limit. It prevents from blasting the boiler, melting the tube, and overheating the fire box crown plate. The constructional details of fusible plug are shown in Figure 4.23. It is located in water space of the boiler. The fusible metal is protected from direct contact of water by gun metal plug and copper plug. When water level comes down, the fusible metal melts due to high heat and copper plug drops down and holds in gun metal ribs. Steam comes in contact with fire and extinguishes it. Thus, it prevents damages.

Figure 4.23 Fusible Plug