🔍 Key Concepts

• Boiler water gauge glass purpose and how it indicates actual drum water level • Function of drain valve versus upper and lower root (shutoff) valves on the gauge glass • What happens to the water level in the glass if steam/water passages are blocked or not in free communication with the boiler

💭 Think About

• Think about which valve operation would momentarily prove that the gauge glass is in open communication with the boiler, from both the steam side and the water side. • Ask yourself: which action will cause a visible and immediate reaction in the glass (or from the fittings) that confirms the passages are clear? • Consider which valve, if opened briefly, will safely show that the gauge glass is not plugged with sediment or scale without disturbing normal operation.

✅ Before You Answer

• Identify the normal position and function of the upper and lower root valves and the drain valve on a gauge glass assembly. • Consider what you should see (or hear) when the correct valve is cracked open momentarily if the gauge glass is working properly. • Verify which choice gives a clear, positive indication that steam and water can freely enter and leave the glass, rather than just relying on ship motion.