Test Study Flashcards
Name three types of metering devices.
- Capillary tube
- Thermostatic expansion valve
- Automatic expansion valve
If the contamination from a burned out compressor reaches the new compressor, the new compressor
will probably:
Burn out
What are the three main functions of a TXV:
a. Provide a constant amount of evaporator superheat
b. Keep the entire evaporator full of regrigerant
c. Prevent floodback of refrigerant to the compressor
d. ALL OF THE ABOVE
Air can enter a refigeration system in what three ways:
A. through leaks
b. poor charging procedures
C. poor recovery procedures
What will be the effect on a refrigeration system if too small a diameter of tubing is used for the capillary control?
The evaporator will starve
Oil removed from a system should be handled carefully because?
It can cause skin burns
Name two devices used to detect refrigerant leaks in a system.
a. Ultraviolet detection
b. Halide torch leak
c. Electronic leak detector
Can a refrigerant be reused after a burnout?
No
Why is it necessary to have superheat in a refrigeration system?
To ensure refrigerant is in a vapor state
What does the term TEWI mean:
Total Equivelant Warming Impact
What does the term CAA stand for:
Clean air act
How many classes is the CAA divided into:
2
Section 608 of the CAA prohibits individuals from knowingly doing what.
Knowingly venting off refrigerants into the atmosphere
The EPA has established a mandatory technician certification program, which has how many tipes or certifications?
4
According to the EPA equipment used for the recovery and recycling of refrigerant must be equipment with what:
Low-loss fittings
Name the four stages of refrigeration cycle:
- Expansion
- Evaporation
- Compression
- Condensation
The heat energy that causes a liquid refrigerant to change to a vapor at a constant saturation temperature for a given pressure, is called :
Latent heat
_________Is the pressure at which the refrigerant changes state from a vapor to a liquid.
Condensing pressure
__________ is the pressure at which the refrigerant changes state from a liquid to a vapor.
Evaporating pressure
The _________ function is to circulate refrigerant.
Compressor’s
What is the function of the discharge line?
To carry high pressure superheated vapor from the compressor discharge valve to the entarce of the condenser
What does the receiver do in a refrigeration system?
Acts as a surge tank
What does the liquid line do in the refrigeration system?
Transports high pressure subcooled liquid to the metering device
The metering device is a restriction that separates the high pressure side from the________ side in a refrigeration system.
Low side
The metering device meters liquid refrigerant from the liquid line to the.
Evaporator
Superheat on the systems low side can be divided into two types, what are they?
Evaporator superheat, total compressor superheat
What does the TXV control?
Evaporator superheat
Name four situations that can cause low evaporator loads.
- Evaporator fan motor not operating
- Iced up or dirty coil
- Defrost circuit malfunction causing coil icing
- End of the refrigeration cycle
- Low air flow across evaporator coil
- Low refrigerant charge
Flooding is when liquid refrigerant enters the compressor while the compressor is running? T/F
True
Name two reasons why slugeine might occurina refrigeration system.
- Bad TXV
- Low load
- Dirty evaporator
- overcharge
Subcooling always refers to a liquid at a temperature __________ its saturation temperature for a given pressure.
Below
The evaporator, like the condenser, acts as a
Heat exchanger
The suction line transports low pressure superheated vapor from the evaporator to the
Compressor
If a capillary tube system is overcharged, it will back up the excess liquid in the condenser, causing high head pressures. T/F
True
Why is it important to install a filter drier before the capillary tube?
Catch foreign objects
What is the color code for R-11 refrigerant?
Orange
What is the color code for R-12 refrigerant?
Yellow
What is the color code for R-134a refrigerant?
Blue
Air and _________ are detrimental to a refrigeration system.
Moisture
New and replacement compressors are shipped with a dry nitrogen charge that must be remotes and then________before using.
Evacuated
