What is the result if standing chilled water is left in the tubes and freezes while a deep vacuum is pulled on the machine?
Correct Answer
C) The ice splits the tubes and water floods into the refrigerant side
Water expands as it freezes, and a tube full of ice has nowhere to grow but outward. The tube wall splits, and when the water thaws it runs into the refrigerant side of the machine. What began as a routine recovery becomes a tube replacement plus a contaminated charge and a machine full of moisture. This is why the water is drained or kept circulating before the vacuum is pulled and why the saturation temperature is watched during the job.
Why This Is the Correct Answer
Ice expansion generates enough force to rupture a copper tube from the inside. Once a tube splits, the water side and refrigerant side are connected, so water floods the shell as soon as the system thaws or the pumps restart. The repair then involves plugging or replacing tubes and dealing with a wet, contaminated machine.
Why the Other Options Are Wrong
Option A: The recovery machine stalls but the chiller itself is unharmed
The chiller takes the damage, not the recovery machine. A ruptured tube bundle is one of the most expensive failures on this equipment.
Option B: The refrigerant absorbs the ice and recovery simply takes longer
Refrigerant does not absorb ice. Water and refrigerant are separated by the tube wall until that wall fails. By the time anything is absorbed, the tube has already split and the repair is under way.
Option D: The tube sheet gaskets weep slightly and air enters the machine
Weeping gaskets are a minor nuisance compared with what actually happens. Frozen tubes rupture rather than simply leak at the joints.
Memory Technique
Ice pushes outward with no mercy. Water in a tube plus a deep vacuum equals a split bundle.
Reference Hint
Deep vacuum lowers the refrigerant saturation temperature; if tube water reaches freezing, the tubes rupture and water contaminates the charge.
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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