Refrigeration & Air Conditioning USCG Question #893 (Set 16)

If the needle and seat assembly is excessively eroded, the valve cage assembly can be replaced. In replacing the original valve cage assembly rated at 1/2 tons, what would be the result if the replacement valve cage was oversized at 5 tons? Illustration GS-RA-07 Illustration GS-RA-07: the U.S. Coast Guard has not released this illustration.

Official USCG Answer & Rule Citation

Correct Answer: Option D — The expansion valve would hunt excessively, alternately starving and overfeeding the evaporator coil.

Installing an oversized valve cage drastically increases port area, causing the thermal expansion valve to continuously overfeed and starve the evaporator, resulting in severe hunting.

100% Free & Open Access — No daily limits, paywalls, or gated answers on BrightMariner.