How does a technician tell when a recovery cylinder taking an R-123 charge has reached its filling limit?
Correct Answer
A) By keeping the cylinder on a scale and watching the net weight
Low-pressure refrigerant develops very little pressure at room temperature, so the cylinder gauge stays near the bottom of its scale even as the cylinder fills up. Pressure tells you almost nothing here. The reliable method is a scale: know the cylinder's tare weight, know its rated capacity, and stop at the allowed fill level by net weight. Frost lines do not form reliably with a refrigerant this warm, and recovery machine run time has no fixed relationship to pounds transferred.
Why This Is the Correct Answer
Weight is the only dependable indicator with a low-pressure refrigerant, because its vapor pressure at room temperature is too low to move the cylinder gauge meaningfully. Working from tare weight and rated capacity lets the technician stop at the correct fill level rather than guessing.
Why the Other Options Are Wrong
Option B: By waiting for the cylinder pressure to reach its marked service pressure
The service pressure marked on a cylinder is a design rating, not a fill indicator, and a low-pressure refrigerant will never approach it at room temperature.
Option C: By feeling the outside of the cylinder for a frost line
Frost lines can suggest a liquid level on some cold refrigerants, but R-123 near room temperature produces no reliable frost line.
Option D: By counting the running hours logged on the recovery machine
Run time varies with vapor density, hose size and machine condition, so it cannot be converted into pounds transferred. Two identical machines can take very different amounts of time to give up the same weight.
Memory Technique
No pressure, no clue. Weigh it, because the gauge will lie to you all day.
Reference Hint
Recovery cylinder fill is judged by net weight on a scale, because low-pressure refrigerant develops almost no pressure at room temperature.
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?
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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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