🔍 Key Concepts

• Purpose of a reserve feed water tank in a marine boiler system • What can happen when you insert any foreign object (like a rod or tape) into high‑purity feed water • The difference between accuracy of a sounding and contamination risk

💭 Think About

• Ask yourself why feed water has to be much cleaner than ordinary fresh water. What types of impurities cause problems in boilers? • Think about what an uncoated metal rod or tape might carry on its surface from the engine room environment. • Consider whether a single sounding automatically makes the reading very inaccurate, or whether the bigger concern might be something else.

✅ Before You Answer

• Verify what happens to boiler performance if even small amounts of oil or dirt enter the feed water system. • Consider whether a "dry" rod or tape is truly free of oil film, rust, or dirt in a machinery space. • Decide which option best reflects the most serious practical consequence of using an uncoated sounding device in a high‑purity water tank.