Once the liquid is out of a low-pressure chiller, where should the technician make the connection for the vapor phase of the recovery?
Correct Answer
D) High on the shell, above the liquid level, so oil and liquid are not pulled into the recovery unit
Vapor is taken from the highest connection available on the vessel, which is where the vapor space is and where nothing but gas can enter the hose. Pulling from a low connection at this stage drags oil and any remaining liquid into the recovery unit, which slugs the compressor and fills the unit's filter with oil. The order matters: liquid comes out of the bottom first, then the connection moves to the top for the long vapor pull.
Why This Is the Correct Answer
The vapor phase moves gas, and gas is at the top of the vessel. Taking suction high keeps oil and liquid out of the recovery machine, protecting its compressor and keeping its filter from loading up. It also gives the vapor a clear path instead of making it bubble up through liquid to reach the hose.
Why the Other Options Are Wrong
Option A: At the oil sump drain, so the refrigerant boiling out of the oil is captured with the vapor
The oil sump does hold dissolved refrigerant, but pulling the vapor phase through it sends oil straight into the recovery unit and does nothing for the vapor in the shell.
Option B: Low on the shell, below the liquid level, so any remaining liquid comes out with the vapor
A low connection is correct for the liquid phase and wrong once the liquid is gone. At this stage it delivers oil and slugs to the recovery compressor.
Option C: At the purge unit's suction line, so the last of the non-condensable gas leaves with the vapor
The purge suction line is small, restricted and connected to a device with its own job. Recovery flow does not belong in it.
Memory Technique
Gas floats, oil sinks. Put the vapor hose where the gas is.
Reference Hint
Vapor recovery is taken from a connection above the liquid level so that oil and liquid do not enter the recovery unit.
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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