Understanding Boiler Accessories

Boilers are complex systems with various components that ensure safe and efficient operation. These components are broadly classified into two categories: boiler mountings and boiler accessories.

• Boiler Mountings: These are essential fittings required for the safe operation of a boiler. They are usually attached directly to the boiler shell and include safety valves, pressure gauges, water level indicators, fusible plugs, steam stop valves, blow-off cocks, and feed check valves.
• Boiler Accessories: These are devices installed to improve the overall efficiency of the boiler plant, although they are not strictly essential for the boiler's safe functioning. Examples include economisers, superheaters, air preheaters, and feed water pumps.

Let's examine the given options based on these definitions:

• Fusible plug: This is a safety device designed to melt at a specific temperature, allowing steam or water to escape and extinguish the fire in case of low water level. It is a boiler mounting.
• Economiser: This device preheats the feed water entering the boiler using the hot flue gases escaping from the boiler. This recovers some of the heat that would otherwise be wasted, thereby increasing the boiler's efficiency. It is a boiler accessory.
• Pressure gauge: This instrument measures the pressure of the steam inside the boiler. It is a safety and control device, thus a boiler mounting.
• Steam stop valve: This valve controls the flow of steam from the boiler to the main steam pipe or header. It is essential for controlling steam supply and isolation, making it a boiler mounting.

Based on the classification, the Economiser is a boiler accessory because its primary function is to improve the efficiency of the boiler by utilizing waste heat from flue gases.