🔍 Key Concepts

• The purpose of adding sodium sulfite (or similar sulfite compounds) to boiler feed water • The relationship between sulfite and corrosion from dissolved gases in boilers • Difference between pH control, hardness control, and oxygen control in boiler water treatment

💭 Think About

• Ask yourself: What specific problem in a boiler does sulfite treatment primarily address—scale from minerals, acidity/alkalinity, or corrosion from gases? • Which water treatment chemical is normally used to tie up calcium/magnesium hardness, and is that the same role sulfite plays? • How would an excess of dissolved oxygen affect boiler metal surfaces, and what kind of chemical would you use to reduce that risk?

✅ Before You Answer

• Be clear on what pH control means (acid vs. alkaline) and which chemicals are typically used for that. • Review which tests are normally used to measure hardness versus those used to monitor dissolved oxygen scavengers like sulfite. • Think about why a marine engineer would regularly test for sulfite residual in a working auxiliary boiler’s feed water.