🔍 Key Concepts

• Boiler safety interlocks on fuel systems • Relationship between air supply (forced draft) and safe fuel combustion • What conditions create a risk of fuel-rich or unsafe combustion in a boiler furnace

💭 Think About

• Which of these events would make it unsafe to keep spraying fuel into the furnace, even if everything else was running normally? • Think about what must happen to the fuel supply if the air needed for combustion is suddenly lost. • Which options relate directly to combustion safety versus just normal operating changes (like pressure or temperature variations)?

✅ Before You Answer

• Identify which choice is tied to loss of combustion air rather than just normal boiler operation limits. • Ask: in which case would continuing fuel flow most likely cause unburned fuel accumulation in the furnace? • Confirm which device (solenoid valve) is typically used as a safety shutoff for fuel, not just as a control for routine operating adjustments.