🔍 Key Concepts

• Closed freshwater cooling systems vs. open/raw water systems • Typical uses of nitrite chemical treatments in engine cooling water • Difference between corrosion control, biological control, and changing freezing/boiling points

💭 Think About

• Ask yourself: In engine cooling systems, what are nitrite-based treatments most commonly advertised to protect against? • Which of the listed functions (A–D) are usually handled by additives like glycol (antifreeze) rather than nitrite packages? • Think about what problem would be worst inside steel engine jackets and cooling passages if untreated freshwater was left circulating for months or years.

✅ Before You Answer

• Identify which option is directly related to metal surface protection inside jackets and coolers. • Decide which options (if any) are mainly a side effect rather than the primary purpose of nitrite treatment. • Recall that antifreeze mixtures (like ethylene/propylene glycol) are the usual way to significantly lower freezing point and raise boiling point, not nitrites alone.