Question 154Refrigeration/AC - 1st Asst/Chief70% to pass
Vapor bubbles present in the liquid upon arrival to the thermal expansion valve in a refrigeration system may cause erosion of the expansion valve's needle and seat. This, in turn, could cause what condition?
AI Explanation
The correct answer is D) TXV hunting.
Vapor bubbles in the liquid arriving at the thermal expansion valve (TXV) can cause the valve to "hunt" or cycle rapidly between open and closed positions. This is because the vapor bubbles reduce the density of the liquid, causing the TXV to open wider than necessary. This in turn results in the valve overcompensating and closing too much, creating an unstable, hunting cycle that can damage the needle and seat over time.
The other options are incorrect because: A) freezing open would not occur due to the vapor bubbles, B) overheating is not a direct result of the vapor bubbles, and C) freezing shut is the opposite of the hunting behavior caused by the vapor bubbles.
Related Questions
#152 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 #153 If the superheat value of the thermostatic expansion valve is adjusted too high, what would be the result? #155 An obstructed expansion valve may be indicated by an incompletely cooled evaporator and what other symptom? #156 Moisture entering a typical refrigeration system will most likely produce what effect? #157 A small obstruction at the thermostatic expansion valve inlet will result in which of the following conditions?