Question 124Refrigeration/AC - QMED70% to pass
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? Illustration GS-RA-13
AI Explanation
The correct answer is C) the highest.
When all four evaporators of a multi-box refrigeration system are actively being fed with liquid refrigerant, the control oil pressure acting on the hydraulic relay piston will be at its highest value. This is because the capacity controlled compressor needs to operate at its maximum capacity to meet the cooling demand of all four evaporators, which requires the highest control oil pressure to fully open the unloader mechanism and allow the compressor to run at its maximum output.
The other options are incorrect because A) the lowest control oil pressure would not allow the compressor to meet the cooling demand, and B) the mid-range control oil pressure would not be sufficient to fully open the unloader mechanism. Option D is incorrect because the lube oil system is directly involved in the operation of the unloader mechanism, which controls the compressor's capacity.
Related Questions
#122 A refrigeration compressor used in a multi-box refrigeration system is designed with six of its eight cylinders able to be controlled for variable load conditions. If all of the reefer boxes are currently feeding, what percentage of the total number of compressor cylinders will be loaded after start up? #123 On a modern refrigerated container unit employing suction modulation for the purposes of capacity control and capacity limitation, what happens when the applied voltage and current draw associated with the normally open (NO) suction modulation valve located in the suction line both increase? #125 The fluid used as a source of actuating power against the underside of the unloader power element piston of the refrigeration compressor capacity control mechanism illustrated is obtained from where? Illustration GS-RA-13 #126 Minor repairs may be performed on low-pressure refrigerant systems without recovering the refrigerant charge if the pressure in the system is raised to atmospheric. How may this be accomplished? #127 The most cost-effective method of recovering refrigerant from a low-pressure chiller with more than 500 lbs of refrigerant and to meet EPA requirements is to recover the refrigerant using what protocol?