Sodium sulfite, often catalyzed to react faster, is the standard choice in low and medium pressure boilers, and operators test for a sulfite residual to prove enough is present, commonly in the 20 to 40 ppm range. Higher pressure plants use volatile scavengers such as carbohydrazide or DEHA that add no solids. The scavenger finishes what the deaerator starts; it is not a substitute for one.
Sulfite residual's zero on the morning test, the scavenger pump lost prime, get it fed before the oxygen gets a foothold.
Also heard as
- scavenger
- O2 scavenger
Related terms
Deaerator
A pressurized feedwater heater that strips dissolved oxygen and carbon dioxide out of boiler feedwater with steam.
Oxygen pitting
Deep localized corrosion pits in boiler steel caused by dissolved oxygen in the water.
Feedwater
The water pumped into a steam boiler to replace the water boiled off, a blend of condensate and treated makeup.
Lay-up
Protecting an idle boiler from internal corrosion during an outage or the off season.