WorksheetsType 3/#2
Total questions: 25
Worksheet time: 13mins
A low-pressure chiller used for comfort cooling must be repaired if it has an annual leak rate of ___of the total charge.
10%
20%
30%
50%
If a strong odor is detected during the recovery process,
The refrigerant is most likely R-717 (Ammonia)
The purge unit on the condenser has opened
A compressor burn-out may have occurred
It is a good indicator that R-123 is the refrigerant being recovered
Where is refrigerant added to a low-pressure system during the charging process?
The access valve on the purge unit entering the condenser.
The lowest access point on the system such as the condenser charging valve
The highest access point on the system such as the evaporator inlet valve
The lowest access point on the system such as the evaporator charging valve.
When charging a low-pressure system, refrigerant should be introduced to the system as a vapor to raise the system’s saturation temperature to a minimum of:
0 degrees
36 degrees
40 degrees
70 degrees
During evacuation of systems with large amounts of water, it may be necessary to:
Increase pressure by introducing nitrogen to counteract freezing
Purge the condenser by removing nitrogen to encourage freezing
Drain the compressor by removing nitrogen to encourage freezing
Decrease pressure by introducing nitrogen to counteract freezing
Because a low-pressure system operates below atmospheric pressure (in a vacuum)
The system is unlikely to have air and moisture enter the system.
Leaks in gaskets or fittings will cause air and moisture to enter the system
Leaks in the gaskets or fittings will cause substantial refrigerant leaks
Leaks in the gaskets or fittings will cause oil clogging at the condenser.
In a low-pressure chiller, air, and other non-condensables collect at the:
Bottom of the compressor
Top section of the compressor
Bottom of the evaporator
Header before the metering device
The most efficient method of leak checking a charged low-pressure refrigeration unit is to:
Pressurized the system using controlled hot water or heater blankets
Pull a 500-micron vacuum and hold for at least 12 minutes
Pull a 20-inch vacuum and hold for at least 24 hours
Pull a 29.9 inch vacuum and hold for at least 24 hours.
The standard for machine room safety is:
ASHRAE-15
ASHRAE-34
AHRI-740
EPA-740
When installing more than one, pressure relief valves must be installed:
In series with each other
In parallel with each other
In the system’s suction line.
On top of compressor head
The EPA-required evacuation level for recovery or recycling equipment used on low-pressure systems is
15 inches Hg
20 inches Hg
25 mm of Hg absolute
30 inches of Hg absolute
When pressurizing a low-pressure system for leak-detection purposes, do not exceed
5 psig
10 psig
15 psig
20 psig
What type of equipment can be worked on with Type III certification?
High-pressure
Medium-pressure
Low-Pressure
Vacuum pressure
How long would an equipment owner or operator have to retrofit or retire an appliance that has exceeded the threshold leak rate if the replacement appliance uses 50 lbs or more of an exempt refrigerant?
24 months
18 months
12 months
3 months.
Which of the following best describes the refrigerant recovery process from an R-123 system?
Start with vapor removal and then switch over to liquid recovery
Start with liquid removal and then switch over to vapor recovery
Run the compressor and only recover refrigerant in the liquid state.
Run the compressor and only recover refrigerant in the vapor state
What can be used to pressurize a chiller system before opening the system for a non-major repair?
Controlled hot water
Nitrogen
R-409A
Compressed air
The rupture disk on a low-pressure chiller has a burst pressure of:
5 psig
10 psig
15 psig
20 psig
Where is the purge unit located in a low-pressure system?
The top of the condenser
In the lowest location
Above the shell
Before the oil separator
To repair a chiller operating with R-22, the technician:
Does not need a certification
Must have a Type I certification
Must have a Type II certification
Must have a Type III certification
Which of the following refrigerants has a safety classification of B-1
CFC-12 (R-12)
HFC-134a (R-134a)
HCFC-123 (R-123)
CFC-11 (R-11)
Which organization establishes the refrigerant safety group standards?
AHRI
UL
ASHRAE
ASE
When leak testing a low-pressure chiller, the maximum pressure to use is:
5 psig
10 psig
15 psig
20 psig
The owner must keep records of refrigerant added to a low-pressure system during service and maintenance if the system charge is:
25 lbs or greater
50 lbs or greater
100 lbs or greater
150 lbs or greater
Under ASHRAE Standard 34, R-134 is classified as:
A1
A2
B1
b2
A typical setting for the high-pressure cutout control on a recovery unit used for evacuating the refrigerant from a low pressure chiller is:
2 psig
5 psig
10 psig
15 psig
