What is the function of a boiler blowdown tank?

• A. Stores filtrate from boiler water.
• B. Collects and cools blowdown water; vented and equipped with relief devices and proper drainage to prevent scalding and overpressure.
• C. Stores condensate.
• D. Filters the feedwater.

Answer: (B)

The key idea is that a boiler blowdown tank is the safe receptacle for the hot blowdown water that leaves the boiler. When blowdown is discharged, you don’t want incredibly hot, pressurized liquid going straight to the sewer or being discharged in a way that could injure someone. The tank collects the blowdown, cools the water so it’s less hazardous to handle and to discharge, and provides proper venting and drainage. The vent lets any steam escape, and the relief devices prevent pressure from building up inside the tank. Proper drainage ensures the cooled blowdown can be discharged safely without causing scalding or overpressure in the piping or sewer system. In short, it’s a safety and stabilization point for the blowdown process.