How is the efficiency of a purge unit on a low-pressure machine judged?
Correct Answer
A) By how little refrigerant it loses for each pound of non-condensable gas it removes
A purge unit cannot vent air without carrying some refrigerant vapor along with it. An efficient purge separates the two well, so very little refrigerant leaves the machine for every pound of air it removes, while an inefficient older purge can throw away a surprising amount of charge over a season. Since the vented refrigerant is lost to the atmosphere, purge efficiency is both an environmental issue and a real operating cost. Retrofitting a high-efficiency purge is a common upgrade on older centrifugals.
Why This Is the Correct Answer
The measure is a ratio: refrigerant lost against non-condensables removed. A high-efficiency purge chills and separates the mixture so almost pure air is released and the refrigerant condenses back into the machine. Less loss per pound of air removed means a more efficient purge and less refrigerant emitted over the cooling season.
Why the Other Options Are Wrong
Option B: By how quickly it can bring the condenser up to atmospheric pressure after service
Bringing the condenser up to atmospheric pressure is not something a purge unit is meant to do. That condition means the machine lost its charge or took on air, which is a failure rather than a rating.
Option C: By the number of gallons of water it drains out of the evaporator each day in normal service
The purge unit works on the refrigerant side and does not drain the water side at all. Water appearing in the refrigerant circuit signals a tube leak, which is a separate and serious problem.
Option D: By how much oil it manages to return to the compressor on each cycle while running
Oil return is handled by the machine's own oil recovery arrangement. The purge unit is not part of the lubrication system and is not rated on how it handles oil at any point.
Memory Technique
Keep the good, ditch the bad: an efficient purge sends out air and keeps the refrigerant home.
Reference Hint
Purge efficiency is expressed as refrigerant lost per unit of non-condensable removed; high purge run time also indicates a leak.
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?
People Also Study
Business & Financial Management
120 questions · 70% to pass
Contract Administration
60 questions · 70% to pass
Project Management
60 questions · 70% to pass