An 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

Illustration GS-RA-52: the U.S. Coast Guard has not released this illustration.

Question

An 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

Illustration GS-RA-52: the U.S. Coast Guard has not released this illustration.

Accepted Answer

Option D: 150-190 psig. Container refrigeration charts correlate ambient air temperatures with full-capacity head pressures, placing a 90°F ambient condition for R-134a systems within the expected 150 to 190 psig operating discharge range.