🔍 Key Concepts

• Vacuum creation in distilling plants when steam is NOT available • How air ejectors (eductors) work and what they use as a motive fluid • Role of condensation rate vs. air removal in maintaining vacuum

💭 Think About

• Ask which option actually REMOVES air and non‑condensable gases from the system, rather than just improving cooling. • Consider what fluid is readily available continuously on most ships to be used as a motive force in an ejector if steam is not used. • Think about whether connecting to a brine overboard pump would reliably maintain a stable vacuum in the evaporator shell.

✅ Before You Answer

• Identify which choice clearly describes a device that actively extracts air from the evaporator shell. • Check which motive fluid would be available even when auxiliary steam is not in use. • Make sure you distinguish between improving condensation and actively pumping out gases—only one of these truly maintains vacuum.