Engine Refrigeration (Supplementary) USCG Question #242 (Set 4)

Which of the following illustrated expansion valves is designed to maintain a constant evaporator pressure rather than a constant evaporator superheat? GS-RA-24 Illustration GS-RA-24: the U.S. Coast Guard has not released this illustration.

Official USCG Answer & Rule Citation

Correct Answer: Option B — C

Automatic expansion valves (or evaporator pressure regulators) are designed to maintain a constant evaporator pressure rather than superheat, utilizing a pressure-actuated diaphragm opposed by an adjustable spring to regulate refrigerant flow regardless of load fluctuations.

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