In what order does a technician remove the charge from a low-pressure chiller to keep the job from dragging on?
Correct Answer
D) Liquid first from the bottom of the vessel, then the remaining vapor
Most of the charge is liquid, and liquid moves far more refrigerant per minute through a hose than vapor does. Pulling liquid first from the low point of the vessel clears the bulk of the charge quickly. Only after the liquid is gone does the technician switch to vapor recovery, which is the slow part because the remaining refrigerant is at very low pressure and very low density. Reversing the order means spending hours boiling off liquid that could have been pumped in minutes.
Why This Is the Correct Answer
Liquid carries far more mass per unit volume than vapor, so removing it first clears the bulk of the charge in a fraction of the time. The slow, low density vapor phase is then all that remains, and the recovery machine can work on it without also having to boil off hundreds of pounds of liquid.
Why the Other Options Are Wrong
Option A: Liquid and vapor together through a single hose to balance the flow
A single hose taking both phases gives up the speed advantage of liquid recovery and can send slugs of liquid into equipment not meant to take them.
Option B: Vapor first until the machine is in a vacuum, then whatever liquid is left
Pulling vapor first forces the recovery machine to boil the entire liquid charge through the low pressure vapor path, which can add many hours to the job.
Option C: Vapor only, since low-pressure refrigerant flashes to gas on its own
The refrigerant does boil, but only as fast as heat enters the vessel. Waiting for the liquid to flash on its own is not a recovery method.
Memory Technique
Liquid is heavy, vapor is thin. Move the heavy stuff first.
Reference Hint
Remove liquid first, then vapor, because liquid moves far more refrigerant per minute than low-pressure vapor.
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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