A single evaporator tube has been identified as the source of a leak on an older chiller. What does plugging that tube accomplish?
Correct Answer
A) It seals the leak path temporarily, within the number of tubes the manufacturer allows to be plugged
Tapered plugs driven into both ends of the failed tube stop water crossing into the refrigerant side and get the machine through the season. It is a temporary measure. Each plugged tube takes surface out of service and the manufacturer sets a limit on how many may be plugged before the bundle has to be replaced. The machine still has to be dried out, and the leak still has to be recorded and dealt with under the same rules as any other repair.
Why This Is the Correct Answer
Plugging closes the leak path through one tube and lets the machine run, at the cost of a little capacity. It is recognized as a temporary repair, and the manufacturer's plugging limit is what tells an owner when the bundle is finished. Everything else the failure caused, particularly the moisture in the machine, still has to be dealt with.
Why the Other Options Are Wrong
Option B: It restores the bundle to its original condition, so the machine may be returned to full rated duty
A plugged tube is a tube out of service. Capacity falls slightly with each one, and the bundle is not back to its original condition.
Option C: It cancels the repair obligation, because a plugged tube is no longer part of the water circuit
Nothing about plugging removes the repair and record keeping obligations that follow a leak on a covered appliance.
Option D: It replaces the need to dry the machine out, because the water path has been closed off at both ends
Water has already been inside the shell. Closing the path it came through does not remove the moisture it left behind.
Memory Technique
A plug buys a season, not a bundle.
Reference Hint
Plugging a failed tube is a temporary repair limited by the manufacturer's maximum number of plugged tubes.
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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