UNIT 3 Flashcards
Kinetic displacement compressor used in large air conditioning systems.
Centrifugal
Absorbs heat into the system and changes liquid refrigerant to vapor.
Evaporator
Ultrasonic, electronic, halide, bubble solution or dye are devices used for this purpose.
Leak detection
Another name for the discharge line immediately exiting the compressor.
Hot gas line
To process refrigerant to new product specifications.
Refrigerant reclaim
Subcooled liquid goes through this device and changes from high temp/high pressure liquid to low temp/low pressure liquid.
Metering device
Positive displacement compressor that uses two nesting screws.
Screw
12,000 btu/hr.
Ton of refrigeration
Rejects heat from the system, changes high temp/high pressure vapor into high temp/high pressure liquid.
Condenser
Positive displacement compressor that converts circular motion into up and down motion to compress the refrigerant vapor using piston(s) in a cylinder(s).
Reciprocating
The line exiting the condenser is also known as this.
Liquid line
A substance that can be changed readily to a vapor by boiling and then changed back into a liquid by condensing it.
Refrigerant
The line running from the exit of the evaporator to the inlet of the compressor.
Suction line
A positive displacement compressor that uses a rotating drum like piston that squeezes refrigerant against a stationary drum like piston.
Rotary
To remove moisture from air.
Dehumidifying
True or false
The cylinder color for R - 12 is light blue.
False, it is white
True or false
R-410A is a HFC refrigerant.
True
True or false
R-290 has a safety classification of A3.
True
True or false
When a refrigerant is saturated, both liquid and vapor can exist simultaneously.
True
When a refrigerant containing chlorine is burned, what is produced?
Toxins/ fosgene gas
What is the cylinder color for R-420A?
Rose
Name two HFC refrigerants.
R-11 & R-12
Name two HFC refrigerants.
R11 & R12
Name one HC refrigerant
R 290
What HFO refrigerant is being used in automobiles to replace R-134a?
R1234YF
What is the process of refrigeration?
To remove unwanted heat from a substance and transferring that heat to a place where it makes little to no difference.
If the condenser is a standard tube and fin setup, what is the estimated ambient temperature outside of the condenser?
90 F
At what temperature is the liquid refrigerant entering the metering device?
100 F
Low side pressure gauge reads 125 psig for a system using R-410A. Thermocouple at the exit of the evaporator reads 55 F. Calculate superheat.
55-43 = 12 F
High side pressure gauge reads 124 psig for a system using R-134a. Thermocouple placed just before the metering device reads 95 F. Calculate system subcooling.
100 - 95 = 5 F
R-407C at 85 F has a corresponding pressure of ____ psia.
112.3 psia
R-1234yf at 1.67 C has a corresponding pressure of ____ psig
35.01 psig
R-404A at -40 F has a corresponding pressure of ____ psia
19.8 psia
R-22 at 100 F has a corresponding pressure of ____ psig.
195.9 psig
R-410A at 37.78 C has a corresponding pressure of ____ psig.
317 psig
R-134a at 25 psia has a corresponding temperature of ____ C.
-13.89 C
R-22 at 358.9 psig has a corresponding temperature of ____ F.
145 F
R-410A at 50.9 psig has a corresponding temperature of ____ F.
2 F
R404A at 103 psia has a corresponding temperature of ___ C.
5 C
You are going to use the recovery cylinder of R-134a to charge module #7 with 20 oz of refrigerant. How do you check the recovery cylinder to make sure there are no non-condensables in the cylinder?
Check PT chart, if more than temp/press relationship, there’s non-condensables
The data plate on the outdoor condensing unit of a system using R-22 states the subcooling for the system should be 10degrees of subcooling. You hook up your gauges and thermocouples and the high side pressure gauge reads 196 psig. The thermocouple reads 95 F. Calculate subcooling.
Unit is undercharged
High temperature refrigeration is produce by _____.
An air conditioning system
Medium temperature systems typically maintain products at temperatures between ___ F and ____ F.
35 and 40
The ____ and _____ are used to change the vapor to liquid and the liquid back into a vapor.
Condenser and evaporator
High temperature refrigeration systems keep the space cooled from ____F to ____F.
68 to 80
As pressure increases, the boiling point ____.
Increases
What is the reason for insulating the suction line?
- Insulation helps prevent direct outside heat from entering system through suction line.
- Prevent condensation
- Prevent excessive heat from entering system
Sublimation = skipping a phase state
Ex. Ice to vapor
1600 ft3 of air at 80 F enters an air handler with an evaporator coil. The air temperature at the exit of the air handler is 60 F. What is the volume of air leaving the air handler?
1540^3ft
40 ft3 of a gas is stored in a container at 100 F at a pressure of 40 psig. The container is connected to by pipe to one that will hold 60ft^3 for a total volume of 100 ft^3 and the gas temperature is lowered to 80 F. What is the pressure in the combined containers?
6 psig
Low pressure refrigerants have a pressure of ____ psig or lower at a liquid phase temperature of 104 F.
30
True or false
Ester based refrigerant oils are very hygroscopic and will absorb moisture out of the air and through some containers.
True
An average 350 ton, R-123 chiller (Type III), at 0 psig, would still have approximately ___ pounds of refrigerant in the vapor state.
100
Rupture disc on a recovery vessel for low pressure refrigerants relieves at ___ psig.
15
What is the proper Department of Transportation (DOT) marking on a recovery cylinder that is rated for R-410A refrigerant?
A. 4BA350 B. 4BA400 C. 4BW400 D. B & C
D. B & C
True or false
Any system designed to contain a flammable hydrocarbon (HC) or HFO refrigerant has to have a leak test before evacuating to 500 microns or lower.
True
What can you do to help speed up recovery/dehydrating a system?
Heat it & Beat it
True or false
A technician servicing an external electrical circuit or sections of the system that do not involve the refrigerant components does not have to be Section 608 certified.
True
R-407C at 270.8 psig has a corresponding temperature of
155F
