During operating periods of a multi-box refrigeration system using a capacity controlled compressor, when all of the evaporators of a four box plant are actively being fed with liquid refrigerant, the control oil pressure acting on the hydraulic relay piston will be at what value? GS-RA-13

Illustration GS-RA-13: the U.S. Coast Guard has not released this illustration.

Question

During operating periods of a multi-box refrigeration system using a capacity controlled compressor, when all of the evaporators of a four box plant are actively being fed with liquid refrigerant, the control oil pressure acting on the hydraulic relay piston will be at what value? GS-RA-13

Illustration GS-RA-13: the U.S. Coast Guard has not released this illustration.

Accepted Answer

Option C: the highest. When all evaporators are actively feeding, the refrigeration load is maximum, causing suction pressure to rise which maximizes the control oil pressure acting on the hydraulic relay piston to keep all cylinders loaded.