A high efficiency purge unit on an R-123 chiller has a small chamber with a drain fitted to it. What routine service does that chamber need?
Correct Answer
B) It has to be drained of the water the purge has condensed out of the air it removes
Air drawn into a chiller carries water vapor with it, and the purge unit condenses much of that water as it chills the gas mixture to separate the refrigerant. The water collects in a small separator with a drain, and if nobody empties it the chamber fills and water starts finding its way back into the machine. Checking and draining that chamber is a routine item on a chiller service, and a chamber that fills quickly is another indication of a significant air leak.
Why This Is the Correct Answer
The purge chills the gas it removes so refrigerant condenses and can be returned to the machine. Water vapor that came in with the air condenses at the same time and collects in a separator. Draining it is part of routine purge maintenance, and the rate at which it fills is a direct measure of how much moist air the machine has been drinking.
Why the Other Options Are Wrong
Option A: It has to be topped up with fresh oil, because the purge compressor draws its lubricant from it
Purge compressors carry their own oil charge, and no purge is designed to be lubricated from a water separator.
Option C: It has to be filled with dry nitrogen, because that is what carries the non-condensable gas out
Nothing is added to a purge unit to carry gas out. The purge compressor moves the gas, and the separator only collects what condenses.
Option D: It has to be pumped down with the recovery unit, because it holds the machine's spare charge
The chamber holds water, not a reserve of refrigerant, and a chiller does not store spare charge inside its purge unit.
Memory Technique
The purge's drain is a rain gauge for your leak.
Reference Hint
Moist air drawn into a chiller condenses in the purge unit, and the water it produces collects in a separator that has to be drained.
More epa-608-type-3 Questions
Some jobs on a chiller count as a major repair under the refrigerant rules, which changes what a technician is allowed to do with a badly leaking machine. Which job falls into that category?
An owner asks how many pounds of refrigerant the rules allow to be left inside a chiller once the recovery has been signed off. What is the correct answer to give him?
The motor of a hermetic centrifugal chiller sits inside the pressure boundary rather than outside it on a shaft. What follows from that construction?
An oxygen monitor is used to decide whether a chiller machine room is safe to enter after a refrigerant release. Below what oxygen reading is the atmosphere treated as oxygen deficient?
A low-pressure chiller's rupture disc has a discharge line running from it. Where does that line have to terminate?
A refrigerant vapor detector in a chiller machine room reaches its alarm level. Besides sounding, what is that alarm expected to do?
Which piece of equipment requires a technician to hold Type III certification before it may be serviced?
What property of the refrigerant is what actually places an appliance into the low-pressure category?
During normal operation, what condition exists inside the evaporator of a running low-pressure centrifugal chiller?
In what unit is the required final recovery vacuum for a low-pressure appliance normally expressed?
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