Question 127Refrigeration/AC - Assistant Engineer70% to pass
A high-pressure centrifugal chiller currently charged with R-134a is being evaluated for the need for leak testing. Using the leak test procedures decision tree illustrated and the R-134a pressure-temperature chart illustrated, with the machine idle and the pressures equalized at 10 psig with an ambient temperature of 60°F, what statement is true? Illustration GS-RA-47
AI Explanation
The correct answer is B.
The machine has a suspected leak because the pressure is only 10 psig, which is lower than the typical operating pressure for an R-134a chiller. To properly check for leaks, the refrigerant pressure should be raised to 35 psig by adding refrigerant, as stated in answer choice B. This is in accordance with the leak test procedures decision tree, which indicates that if the system pressure is below the normal operating range, refrigerant should be added to bring the pressure up to the normal range before performing the leak test.
The other answer choices are incorrect because adding nitrogen (choice A) is not the appropriate method, the machine does not definitely not have a leak (choice C), and checking for leaks without adjusting the pressure (choice D) would not provide an accurate assessment of the system's leak status.
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