Engineering · Steam — Combustion
Before lighting off a boiler, the furnace must be purged (pre-fired with the forced-draft fan) to:
- AWarm the refractory
- BClear any accumulated combustible gases that could explode on ignition✓ Correct
- CDry the feedwater
- DTest the safety valve
Explanation
Purging sweeps out any unburned fuel/gas left in the furnace and uptakes. Lighting off without purging risks a furnace explosion (blowback).
Authority: Steam Plants (USCG engineering topic)
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