🔍 Key Concepts

• Boiler furnace purging procedures after flame failure • Dangers of unburned fuel and combustible gases in the furnace • Standard automatic boiler safety interlocks on flame failure

💭 Think About

• Think about what happens inside the furnace if the flame suddenly goes out but fuel has been spraying in. • Which step would reduce the risk of furnace or uptake explosion before you try to get the flame back? • Consider what a properly designed automatic boiler control system would be programmed to do first after detecting flame failure.

✅ Before You Answer

• Verify which option deals directly with removing unburned fuel/combustible gases from the furnace. • Check which options could actually increase the risk of explosion or fire if done immediately after flame failure. • Confirm which procedure is consistent with standard boiler operating and safety manuals for water-tube auxiliary boilers.