< b="" />Fusible Plug

The correct answer is option 'B', the fusible plug. The fusible plug is a safety device that is used to protect the boiler when the water level falls below a minimum level. It is a small metal plug that is fitted into the crown of the firebox of the boiler.

< b="" />Function of the Fusible Plug

The fusible plug acts as a safety valve in case of low water level in the boiler. Its main function is to extinguish the fire in the furnace of the boiler when the water level falls below a certain point. This is important because if the water level in the boiler drops too low, the metal plates and tubes in the boiler can overheat and fail, leading to a potential explosion or other serious damage.

< b="" />Construction of the Fusible Plug

The fusible plug is made up of a brass body with a tapered hole in the center. Inside the hole, there is a fusible alloy or a metal that has a low melting point. The melting point of the fusible alloy is lower than the temperature of the fire in the furnace, but higher than the normal operating temperature of the boiler. This means that under normal operating conditions, the fusible plug remains solid and does not melt.

< b="" />Working of the Fusible Plug

When the water level in the boiler falls below a certain point, the metal plates and tubes in the boiler start to overheat. The heat is transferred to the fusible plug, and when the temperature of the fusible plug exceeds its melting point, the fusible alloy inside it melts. This creates a hole in the plug, which allows the water in the boiler to enter the firebox and extinguish the fire.

< b="" />Advantages of Using a Fusible Plug

- The fusible plug provides an additional layer of safety in case the water level in the boiler drops too low.
- It is a simple and cost-effective safety device that can prevent serious accidents and damage to the boiler.
- The fusible plug is easy to install and maintain, and it does not require any external power source or complicated mechanisms to function.

< b="" />Conclusion

In conclusion, the fusible plug is a safety device that is used to protect the boiler when the water level falls below a minimum level. It acts as a safety valve and extinguishes the fire in the furnace of the boiler when the water level drops too low. The fusible plug is a simple and effective safety device that provides an additional layer of protection for the boiler.