What must be installed in the nitrogen line before a low-pressure chiller is pressurized for a leak test?
Correct Answer
C) A pressure regulator with a relief valve set below the machine's limit
A nitrogen cylinder holds pressure hundreds of times greater than a low-pressure chiller can survive, and the only thing between the two is the regulator. A regulator alone can fail or be misadjusted, so a relief valve set below the machine's allowable test pressure goes in the line as a backstop. With both in place, a mistake at the cylinder cannot burst the rupture disc or damage the vessel. Without them, one turn of the wrong knob ruins the machine.
Why This Is the Correct Answer
The regulator sets the delivered pressure and the relief valve limits what can reach the machine if the regulator fails or is opened too far. Together they keep the test pressure below the level that would burst the rupture disc on a vessel designed for near atmospheric service.
Why the Other Options Are Wrong
Option A: A liquid line filter drier to keep moisture out of the machine during the test
A filter drier belongs in a refrigerant circuit. Nitrogen out of a cylinder is already dry, and a drier does nothing to keep cylinder pressure from reaching a low-pressure machine.
Option B: A sight glass so the technician can watch the gas flow going in
Watching the gas flow provides no protection at all. The hazard is pressure reaching the machine, and a technician watching a sight glass still has no way to stop it.
Option D: An oil separator to keep cylinder residue out of the shell and oil
An oil separator has no role in a nitrogen test line and offers no protection against overpressure. It belongs in a refrigerant circuit and would sit uselessly in a line carrying dry gas.
Memory Technique
Regulator sets it, relief valve saves it. Two devices between a full bottle and a thin shell.
Reference Hint
Nitrogen used to pressurize a low-pressure appliance must pass through a pressure regulator with a relief valve set below the machine's limit.
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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