🔍 Key Concepts

• Function of a boiler gage glass and why it needs protection • How high-temperature water and steam affect glass surfaces over time • What a thin mica shield physically does when in contact with hot water/steam

💭 Think About

• Think about which part of the gage glass needs protection: the glass itself, the space around it, or the gaskets? • Consider the properties of mica: is it known more for being heat-resistant, non‑conductive, or structurally strong against impact? • Which option best matches a realistic failure mode of gage glasses in long-term boiler service?

✅ Before You Answer

• Verify which choice directly relates to protecting the inside surface of the glass from damage by water/steam. • Check whether mica sheets are typically used as a physical shield or as an electrical insulator in this context. • Rule out any option that focuses on parts (like gaskets or fire room protection) that mica does not normally guard in a gage glass.