Question 72Refrigeration & AC - QMED
70% to passAn air-cooled refrigerated container unit using R-134a as a refrigerant has a box temperature set point of -15°F, but it is currently operating with a stable return air temperature of 0°F. The fresh air makeup vent is closed, the unit is operating at 460 VAC/60 Hz, and the unit is in full capacity cool (modulating valve 100% open). Using the illustrated troubleshooting guide, what would be the normal range of expected discharge pressures if the ambient air temperature is 90°F? Illustration GS-RA-52
A150-190 psig
B160-180 psig
C190-230 psig
D200-220 psig
AI Explanation
The correct answer is A) 150-190 psig. The key factors here are the refrigerant used (R-134a), the box temperature set point of -15°F, the return air temperature of 0°F, and the ambient air temperature of 90°F. With these conditions, the normal range of expected discharge pressures for an air-cooled refrigerated container unit using R-134a would be 150-190 psig. This is based on the typical discharge pressure ranges for an R-134a system operating under these temperature conditions. The other answer choices are incorrect because they either fall outside the normal operating range (B and D) or are too high (C) for the given scenario.
Related Questions
Q67:As shown in the illustrated LP centrifugal chiller pressure maintenance system, ... Q88:In a refrigeration system featuring low-side pump down prior to the automatic sh... Q25:A "hygroscopic" lubricant used in refrigeration compressors would have what char... Q81:You are checking the supply chilled water temperature thermistor probe on a high... Q34:Which of the fluids listed is suitable for use as a secondary refrigerant?
Ready to test your knowledge?
Take a Refrigeration & AC - QMED Practice ExamOfficial Resources