🔍 Key Concepts

• Heat transfer in boilers – how heat moves from the flame to the water/steam and where losses occur • Purpose of refractory and insulation – what they normally do in furnaces, ovens, and boilers • Protection of boiler structure – what parts of the boiler need shielding from high temperature

💭 Think About

• Think about where the firebox is located and which boiler components are directly exposed to the flame and high temperatures. • Ask yourself: what do the words refractory and insulation usually mean in any high‑temperature equipment (like kilns, furnaces, or incinerators)? • Consider which option describes a function that BOTH refractory and insulation would logically perform together, instead of a very specialized or narrow function.

✅ Before You Answer

• Identify which choice deals with heat loss and temperature control rather than a very specific mechanical effect. • Check which option refers to protecting boiler structure or casing from high temperature – that is a typical job of refractory material. • Eliminate any options that describe functions that could be handled by burner design, draft control, or tube arrangement rather than by refractory/insulation.