Question 186Refrigeration & AC - 1st Asst/Chief

70% to pass

Which of the listed statements describes the method used to determine the amount of superheat present in the suction gas leaving the evaporator coil? Illustration GS-RA-16

Refrigeration Chief Question 186 diagram
ANote the low side pressure, determine the corresponding saturation temperature, and subtract it from the temperature measured with a thermometer at the compressor suction inlet.
BSubtract the temperature measured at the thermostatic expansion valve sensing bulb from the saturation temperature corresponding to the low side pressure.
CNote the low side pressure, determine the corresponding saturation temperature, and add it to the temperature measured with a thermometer at the thermostatic expansion valve sensing bulb.
DNote the low side pressure, determine the corresponding saturation temperature, and subtract it from the temperature measured with a thermometer at the thermostatic expansion valve sensing bulb.
AI Explanation

The correct answer is D. The method used to determine the amount of superheat present in the suction gas leaving the evaporator coil is to note the low side pressure, determine the corresponding saturation temperature, and subtract it from the temperature measured with a thermometer at the thermostatic expansion valve sensing bulb. This is because the difference between the saturation temperature and the actual temperature of the suction gas is the amount of superheat. The other options are incorrect because they do not correctly describe the method for determining superheat. Option A measures the temperature at the compressor suction inlet instead of the thermostatic expansion valve sensing bulb, and option B subtracts the wrong temperature. Option C adds the saturation temperature instead of subtracting it.

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Official Resources
46 CFR Machinery & Electrical 46 CFR Engineering USCG National Maritime Center
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