Chapter 13 Refrigerants
No
Can any refrigerant serve as a "drop-in" replacement for other refrigerants?
two-stage compressor
Compression ratios higher than 10:1 usually require what kind of compressor?
High-temperature refers to air conditioning or comfort cooling. Medium-temperature refers to refrigerators, Low-temperature refers to freezers.
Give one example of each type of application: high-temperature, medium-temperature and low temperature.
(Condensing pressure + 15) / (suction pressure + 15) Divide the absolute suction pressure into the absolute condensing pressure. Don't forget to add 15 to each of the numbers before dividing.
How is compression ratio calculated?
R-410a
In high-temperature applications, which refrigerant has been replacing R-22 in newer air conditioning systems?
Any compression ratio of more than 12:1
In what instance is a two-stage compressor authorized for use?
Low capacity implies less heat removal so it's not good.
Is low capacity good when cooling a conditioned space?
No
Is the best refrigerant choice one that has low heat capacity (btu/lb) and high power requirements?
No
Is the stability of R-134a good for any application where R-11 would be suitable?
Latent heat value and low material/energy costs
Name some qualities that determine a good refrigerant.
R-502
R-507 was designed as a substitute for a different refrigerant. Which refrigerant was that?
R-22 is at 32.8 psig, R-134a is at 12 psig, R-507 is at 46.15
Refer to a P/T card or saturation chart and determine the gauge pressures for R-22, R-134a and R-507 at 10 degrees F.
5 degrees F evaporating temperature and 86 degrees F condensing temperature
Standard conditions used for testing refrigerants are an evaporating temperature of what and a condensing temperature of what?
500
The azeotropic group of refrigerant is designated by what hundreds number?
CFC
The chemical elements chlorine and fluorine are known as what?
evaporator superheat and suction superheat
The two types of superheat that can be measured are what?
saturation temperature
To determine a superheat value, subtract a thermometer measurement from what other value.
No
To save time and money, should service technicians substitute or mix refrigerants?
At atmospheric pressure R-22 boils at -41 degrees and R-134a boils at -15 degrees
What are the boiling points of R-134a and R-22 at atmospheric pressure?
R-22 is green R-123 is Blue and gray R-134a is light blue R-507 is Teal
What are the color codes for containers used for R-22, R-123, R-134a and R-507?
Suction pressure and condensing pressure
What are the two basic problems of refrigeration systems?
light gray
What color is R-123?
light blue
What color is R-134a?
Pink
What color is R-410a?
ammonia
What is the chemical name for R-717?
CFC
What was the first halide refrigerant?
btu
A refrigerant's latent heat value refers to the number of what absorbed for each pound of liquid evaporated?
Boiling or condensing
A substance at its saturation point can be changing its physical state by either doing what two things?
yes
Are refrigerants so stable that at every point in the refrigeration system their condition can be predicted and controlled?
