Which reading is the warning that water remaining in the tubes may be about to freeze and split them?
Correct Answer
C) Refrigerant saturation temperature in the evaporator reaching thirty-two degrees F
Pressure and temperature travel together in a saturated system, so the low-side pressure gauge on a low-pressure machine is really a thermometer for the refrigerant in the shell. Once that saturation temperature reaches the freezing point of water, any water still standing in the tubes is against ice-cold metal and can freeze. The technician must slow or stop the pull-down at that point and take care of the water side before continuing. This is the reason a Type III recovery is watched continuously rather than left to run unattended.
Why This Is the Correct Answer
The saturation temperature that matches the shell pressure tells the technician how cold the tube metal is becoming. When it drops to the freezing point of water, ice can form inside the tubes and burst them. Reading pressure and converting it to saturation temperature is the direct warning signal, which is why the pull-down is monitored the whole way down.
Why the Other Options Are Wrong
Option A: Condenser water leaving temperature reaching fifty-five degrees F during the pull-down
Fifty-five degrees on the condenser water side is an ordinary reading well above freezing. It says nothing about how cold the refrigerant inside the shell has become while the machine is pumped out.
Option B: Compressor oil sump temperature falling to sixty degrees F on the gauge
Oil sump temperature reflects the oil charge and any sump heater, not the tube bundle. A cool sump on a shut-down machine is normal and is not a freeze warning at all.
Option D: Recovery cylinder weight reaching eighty percent of its rated capacity by weight
Cylinder fill level is a safety limit for the recovery vessel itself. It tells the technician to change cylinders, not that the chiller tubes are approaching the freezing point.
Memory Technique
The gauge is a thermometer: on a saturated shell, pressure equals temperature, and thirty-two is the line you do not cross.
Reference Hint
Freezing point of water is 32 degrees F; low-side saturation temperature must be kept above it while water remains in the tubes.
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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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?
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