An older chiller is charged with R-114, a refrigerant that boils just below forty degrees Fahrenheit at atmospheric pressure. Which class does the regulation place that appliance in?
- AA low-pressure appliance, since chillers of this vintage normally are
Plenty of chillers are high-pressure machines. The word describes what the equipment does for the building, not the pressure class of its refrigerant.
- BA very high-pressure appliance, because of the compressor type used
Very high-pressure describes refrigerants boiling far below zero. Compressor type never enters the classification, which is written entirely around the refrigerant.
- A high-pressure appliance, since the refrigerant boils below the dividing line
- DAn unclassified appliance, since the refrigerant is no longer manufactured
A refrigerant going out of production changes nothing about how its appliances are classified or which requirements apply to servicing them.
Why C is correct
R-114 boils below the dividing line of ten degrees Celsius, about fifty degrees Fahrenheit, at atmospheric pressure, which places its appliances in the high-pressure class. The regulation lists it among the examples of high-pressure refrigerants. Chillers appear in both the high-pressure and low-pressure classes, and the refrigerant rather than the machine style is what settles which one applies.
What this question is testing
This tests classification against a strong misleading cue. The exam builds questions this way deliberately, because in the field the equipment description arrives before the refrigerant data and technicians act on the description.
On the job
Older marine, military and industrial chillers still run on R-114, and a technician who assumes every chiller is Type III work will hand the job to the wrong person. The physical check is quick: a high-pressure machine sits above atmospheric pressure when it is shut down, while a low-pressure machine sits in a vacuum. A gauge on an idle machine answers the question before anyone reads a data sheet.
Memory technique
A chiller can be either. Put a gauge on it cold: pressure means high-pressure, vacuum means low-pressure.
Exam tip
Chiller is not a pressure class. Look up the refrigerant every time, especially on older machines.
Where to look it up
R-114 boils below the ten degree Celsius line and its appliances are high-pressure appliances covered by Type II.