The steam drum at the top holds the working water level and contains separators and scrubbers that strip water droplets from the steam, along with feedwater, chemical feed and continuous blowdown piping. The lower mud drum collects sludge and feeds water to the tubes, and it is where bottom blowdown is taken. Drum level is the single most watched number in a watertube boiler room.
Drum level is swinging plus and minus four inches on the load change, keep an eye on it or we'll trip on low water.
Related terms
Watertube boiler
A boiler in which water and steam circulate inside tubes while the fire and hot gases pass around the outside.
Carryover
Boiler water and the solids dissolved in it leaving with the steam instead of staying in the boiler.
Blowdown
Draining some boiler water on purpose to remove concentrated dissolved solids and settled sludge.
Gauge glass
The glass tube or window on a steam boiler that shows the operator the actual water level.