🔍 Key Concepts

• Flash-type evaporator operation – how distillate is produced and monitored in multiple stages • Salinity cell / salinity panel function – what the selector switch actually does • Three-way solenoid dump valve logic – what signal makes it shift to dump impure distillate

💭 Think About

• Think about what actually TELLS the three-way solenoid valve to move: is it flow, salinity, power loss, or selector position? • Ask yourself: if the salinity is high in any monitored stream, would you ever want impure distillate to be able to reach the freshwater tanks? • Consider whether safety of potable water depends on one particular stage being selected, or on the salinity signal itself.

✅ Before You Answer

• Identify what the cell selector switch really controls (measurement point vs. valve command). • Clarify whether loss of power to the salinity panel causes the valve to fail to ‘make’ fresh water or to fail-safe to dumping it. • Decide if the dump action should depend on a specific stage only, or protect the system no matter which stage is being monitored.