Final Flashcards
Condensing is the change in state from a gas/vapor to a _________
Liquid
The ____________ gauge reads pressures above and below atmospheric pressure
Compound
Name the three types of heat transfer
Convection, conduction, and radiation
Define latent heat
Heat required to change a state of matter
A refrigeration compressor is designed to pump _________
Gas/vapor
What is it called when a solid changes to a vapor, bypassing the liquid state?
Sublimation
If changing water from 32F to 196F is it necessary to add latent heat
No
Name the three states in which most elements and compounds may exist
Solid, liquid, gas
Name the four components of the refrigeration system
Compressor, condenser, meter device, evaporator
When R-502 is at 248 PSIG, at what temperature will it begin to condense
111F (use PT Chart)
Convert 60C to Fahrenheit
140F = (1.8 x 60C) + 32
How many BTUs are in one ton of refrigeration
12,000
When an evaporator using R-12 is boiling the refrigerant at 26F, what is the suction pressure?
25 (use PT chart)
Sublimation is the changing of state from a solid to a liquid
False
By controlling the pressure on a liquid; different boiling temperature may be obtained
True
The specific heat of water is 0.5 BTUs
False
Heat is a form of energy
True
Copper will conduct heat better than glass
True
Heat transfer will take place between two objects of the same temperature
False
Magnetism is not a form of energy
False
Heat transfer is always from warm to cool
True
If the temperature of a refrigerant rises then the pressure will decrease, thus, it is inversely proportional
False
All liquids boil at the same temperature when under the same pressure
False
The formula to calculate BTUs is:
Q = specific heat x latent heat + temperature difference x weight
False
For every pressure applied to a liquid, there is a definite corresponding temperature at which it will boil or condense
True
Approximately how many inches of mercury (manifold gauge) are equal to standard atmospheric PSIG pressure at sea level
29.92
Approximately how many inches of mercury is a perfect vacuum
30
What are the two most common refrigerants used in residential air conditioning
R22 and R410A
The amount of heat in BTUs required to raise the temperature of a substance one degree Fahrenheit is
Specific heat
Water, ice, and steam are an example of
The states of matter
The heat required to melt one pound of ice at 32F to water at 32F equals
144 BTUs
Zero gauge pressure corresponds to an absolute pressure reading of
14.696 psia
Which component is considered the “heart” of the refrigeration system
Compressor
Heat, being a form of energy, cannot be
Destroyed
Condensing is the change in state from gas/vapor to a
Liquid
What is the proper condensing temperature for R22 that has a pressure of 226 PSIG
110 (PT chart)
The unit for measuring the quantity of heat is called the
BTU
How many BTUs per hour are equivalent to one ton of refrigeration
12,000
Ice will begin to melt when it’s sensible temperature rises above
0C
The heat used to change a liquid to a gas is called the latent heat of
Vaporization