Which refrigerant was the original factory charge in most low-pressure centrifugal chillers built during the nineteen sixties and seventies?
Correct Answer
A) R-11
The classic low-pressure centrifugal chiller was charged with R-11, a CFC that boils well above normal room temperature and therefore lets the machine run in a vacuum. R-123 was developed as the drop-in style replacement for R-11 when CFC production ended, and R-113 shows up in a few older machines as well. R-12, R-22 and R-502 are all high-pressure refrigerants used in reciprocating and scroll equipment, where the whole circuit sits above atmospheric pressure and the appliance falls under Type II rules instead.
Why This Is the Correct Answer
R-11 is the original low-pressure centrifugal refrigerant. Its boiling point sits above ordinary room temperature at atmospheric pressure, so a machine charged with it operates partly in a vacuum. That is exactly the behavior the low-pressure appliance class was written around, and it is why R-11 machines fall under Type III.
Why the Other Options Are Wrong
Option B: R-12
R-12 is a high-pressure CFC used in small reciprocating equipment and older auto systems. A machine charged with it runs above atmospheric pressure throughout and is not a low-pressure appliance.
Option C: R-22
R-22 is a high-pressure HCFC found in residential and light commercial equipment. Its saturation pressures are far above atmospheric at room temperature, so it never places an appliance in the low-pressure class.
Option D: R-502
R-502 is a high-pressure blend used in older low-temperature commercial refrigeration. Nothing about it puts a machine into a vacuum, so it belongs to the Type II side of the certification split.
Memory Technique
The low-pressure numbers all sit in the teens and low hundreds with a 1 in front: eleven, thirteen, twenty-three. Think '11-113-123, the vacuum family.'
Reference Hint
Low-pressure appliance class is defined by the refrigerant, and the low-pressure family is R-11, R-113 and R-123.
More epa-608-type-3 Questions
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?
What should a technician do about the water in the chiller tubes before pulling a deep vacuum on the machine?
What happens if the internal pressure of a low-pressure chiller is driven past the rating of its rupture disc?
A running low-pressure chiller develops an opening in a section of shell that is below atmospheric pressure. What passes through that opening?
A technician is assigned to recover the charge from a large water chiller holding nine hundred pounds of R-134a. Which certification does that job require?
Into which appliance category does a machine charged with R-13 for very low temperature service fall?
On a low-pressure centrifugal chiller running at load, how do the evaporator and condenser sit relative to atmospheric pressure?
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