Unit 9

Question 1

Synthetic oil used with HCFC type refrigerants

Answer 1

Alkylbenzene

Question 2

Use of a recover machine to recover refrigerant

Answer 2

active recovery

Question 3

Non-Ozone depleting refrigerant that do not contain chlorine of fluorine

Answer 3

hydrocarbon

Question 4

Consists of three oxygen molecules and is in the stratosphere

Answer 4

ozone

Question 5

Warming process caused by the atmosphere’s absorption of heat energy radiated from the earth’s surface

Answer 5

Greenhouse effect

Question 6

Used mainly in automotive refrigeration systems. Glycol based lubricant attracts and holds moisture readily

Answer 6

Pag oil

Question 7

A blend of refrigerants that has many temperatures as it evaporates and condenses

Answer 7

temperature glide

Question 8

Blend of two or more refrigerants that behave like a pure refrigerant

Answer 8

Azeotrope

Question 9

Use of system compressor or internal pressure to recover refrigerant

Answer 9

passive recovery

Question 10

Used to prevent the loss of refrigerant from hoses when disconnected from a system, recover/refrigerant cylinder or recovery machine

Answer 10

low loss fitting

Question 11

Meeting that set the reduction rates for ozone depleting substances

Answer 11

Montreal Protocol

Question 12

Ester based lubricant that absorbs moisture readily and holds it more tightly. Best if stored in a metal container instead of plastic

Answer 12

POE oil

Question 13

Most refrigerants are ______

Answer 13

heavier than air

Question 14

Which of the following refrigerants is very high pressure?
R134a, R410A, R744 or R1234YF

Answer 14

R744

Question 15

T/F
When a system is known to have a large leak, recover refrigerant from the system until 0 psig is reached to prevent pulling air and noncondensables into the system and into the recovery cylinder

Answer 15

True

Question 16

T/F
Passive recovery involves using nonpressurized containers to collect the refrigerant from the system

Answer 16

True

Question 17

T/F
Liquid density of refrigerant at 77 degrees F may be used to calculate recovery cylinder capacity

Answer 17

True

Question 18

T/F
To prepare a new recovery cylinder to accept refrigerant, the cylinder must be purged of nitrogen and evacuated a minimum of 5000 microns

Answer 18

False;
1000 microns

Question 19

T/F
Never disconnect or unplug anything or begin a service procedure before checking for flammable refrigerant in the area with a combustible gas leak detector or monitor

Answer 19

True

Question 20

T/F
The letter “A” at the end of “R-410A” signifies that it is an isomer of R410

Answer 20

False.
A means same ingredient but different proportion

Question 21

T/F
The lower exposure limit (LEL) of a gas is the lowest concentration of the gas in air capable of producing a flash or fire in the presence of an ignition source

Answer 21

True

Question 22

T/F
Retrofitting of a system with HC or other flammable refrigerant is allowed in the United States as long as proper safety precautions are followed

Answer 22

True

Question 23

T/F
Never use fuel grade propane in a refrigeration system

Answer 23

True

Question 24

T/F
Carbon dioxide is the number on contributor to global warming

Answer 24

True

Question 25

T/F
Tropospheric ozone is considered good ozone

Answer 25

False

Question 26

T/F
The higher the temperature glide, the higher the fractionation potential

Answer 26

True

Question 27

Most refrigerants are made of _______ and ________ molecules

Answer 27

Methane and Ethane

Question 28

Ozone depletion happens in the _______. Global warming happens in the _________.

Answer 28

Stratosphere.
Troposphere.

Question 29

It is illegal to vent CFC and HCFC refrigerants as of

Answer 29

July 1, 1992

Question 30

What type of refrigerant is classified as “natural refrigerants”?

Answer 30

HC refrigerants. Example: Propane

Question 31

What is the visual indicator that a system uses flammable refrigerant?

Answer 31

There should be flammable hazard signs on the plates near the compressor/ evap. Service lines are also painted red

Question 32

Draw a diagram of a recovery machine hooked up to a system using a three-hose, two-valve manifold. Show placement of the filter drier, recovery cylinder and scale using the Appion method of recovery.

Answer 32

Along with diagram, choose appropriate valve position for each valve in system

Question 33

Calculate recovery cylinder capacity. Using formulas.

Answer 33

Be mindful of DOT stamping. 4BA”350” not acceptable

Question 34

What is the pressure on the low side pressure gauge if the evaporator temperature is -10 degrees F for a system that uses R-410A?

Answer 34

36.4 psig based of PT chart

Question 35

High side pressure gauge reads 114 psig. At what temperature is the R134a refrigerant changing back to liquid inside the condenser?

Answer 35

95 degrees F based on PT chart

Question 36

The ambient temperature near a standard fin and tube condenser is 95F. What is the condensing temperature inside?

Answer 36

125 degrees F

Question 37

Never exceed the design _________ side factory test pressure on the name plate when pressurizing a system with nitrogen

Answer 37

Low

Question 38

When changing an outdoor condensing unit from R-22 to R-410A, what is one problem that may occur if the evaporator isn’t changed at the same time?

Answer 38

The difference in operational pressures may result in evaporator leaks.
TXV may also need adjusting.

Question 39

What type of refrigerant blend is a long-term replacement for HCFC blends?

Answer 39

HFC refrigerant

Question 40

Pressure relief valves should always be installed in ________ with one another, never in series

Answer 40

parallel