🔍 Key Concepts

• Trace the piping connected to valve 25 and determine whether it leads to the distiller shell, the jacket‑water system, or to atmosphere. • Think about how a vacuum distiller works: lower absolute pressure lowers the boiling point and increases distillate output. • Consider what happens to the unit’s pressure, boiling point, and controls if air is accidentally admitted into the evaporator while operating.

💭 Think About

• If valve 25 opens, does it admit air, bypass water, or simply isolate a gauge or fitting? How would each of those affect vacuum and distillate production? • Would opening valve 25 cause any automatic control or safety device (pressure switch/contacts) in the circuit to change state, or would the unit continue running but less efficiently? • Compare which options describe a change in absolute pressure inside the shell versus a change in jacket‑water flow path.

✅ Before You Answer

• Verify exactly where line 25 discharges (into the shell, overboard, atmosphere, or back to a system). • Identify which component in the diagram is tied to the low‑pressure contacts and see if it is directly influenced by valve 25. • Confirm whether any valve shown on the jacket‑water bypass line is labeled 25, or if 25 is instead associated with venting or vacuum‑breaking on the distiller shell.