What is the purpose of a boiler blowdown tank and what safety features are typical?

• A. To store fresh make-up water for the boiler.
• B. To collect and cool blowdown water; typically vented and equipped with relief devices and proper drainage to prevent scalding and overpressure.
• C. To filter impurities from feedwater.
• D. To adjust boiler firing rate.

Answer: (B)

Blowdown water from a boiler is hot and carries dissolved solids, so the tank provides a dedicated place to receive that discharge, let it cool, and allow solids to settle before safe disposal. The tank is vented so any steam can escape rather than building pressure, and it has a relief device to prevent overpressure from the incoming blowdown. A proper drain and backflow protection ensure the discharge is removed safely without backflow into the system or creating scalding hazards. Cooling is achieved by the tank’s volume (and sometimes internal features that promote heat transfer), so the water is at a safe temperature before it’s discharged. In short, it safely collects, cools, vents, and drains blowdown water to protect people and equipment.