🔍 Key Concepts

• Behavior of ammonia as a refrigerant, especially when it contains moisture • Which common metals in refrigeration systems are compatible or incompatible with ammonia • Typical construction materials of piping and components in ammonia refrigeration plants

💭 Think About

• Think about which metals are normally selected for ammonia refrigeration systems and why others are avoided. • Ask yourself: if ammonia with water becomes more corrosive, which metals would suffer the most corrosion in that environment? • Consider whether copper‑based alloys (like brass/bronze) behave differently with ammonia than iron or steel do.

✅ Before You Answer

• Identify which metals in the options are copper‑based alloys versus ferrous metals (iron/steel). • Recall (or look up) which metals are specifically prohibited or strongly discouraged for use with ammonia refrigerant. • Verify which of the listed metals are normally used successfully in ammonia systems—those are less likely to be the ones that the corrosive mixture attacks.