Unit 9 Flashcards
Synthetic oil used with HCFC type refrigerants
Alkylbenzene
Use of a recover machine to recover refrigerant
active recovery
Non-Ozone depleting refrigerant that do not contain chlorine of fluorine
hydrocarbon
Consists of three oxygen molecules and is in the stratosphere
ozone
Warming process caused by the atmosphere’s absorption of heat energy radiated from the earth’s surface
Greenhouse effect
Used mainly in automotive refrigeration systems. Glycol based lubricant attracts and holds moisture readily
Pag oil
A blend of refrigerants that has many temperatures as it evaporates and condenses
temperature glide
Blend of two or more refrigerants that behave like a pure refrigerant
Azeotrope
Use of system compressor or internal pressure to recover refrigerant
passive recovery
Used to prevent the loss of refrigerant from hoses when disconnected from a system, recover/refrigerant cylinder or recovery machine
low loss fitting
Meeting that set the reduction rates for ozone depleting substances
Montreal Protocol
Ester based lubricant that absorbs moisture readily and holds it more tightly. Best if stored in a metal container instead of plastic
POE oil
Most refrigerants are ______
heavier than air
Which of the following refrigerants is very high pressure?
R134a, R410A, R744 or R1234YF
R744
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
True
T/F
Passive recovery involves using nonpressurized containers to collect the refrigerant from the system
True
T/F
Liquid density of refrigerant at 77 degrees F may be used to calculate recovery cylinder capacity
True
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
False;
1000 microns
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
True
T/F
The letter “A” at the end of “R-410A” signifies that it is an isomer of R410
False.
A means same ingredient but different proportion
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
True
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
True
T/F
Never use fuel grade propane in a refrigeration system
True
T/F
Carbon dioxide is the number on contributor to global warming
True
T/F
Tropospheric ozone is considered good ozone
False
T/F
The higher the temperature glide, the higher the fractionation potential
True
Most refrigerants are made of _______ and ________ molecules
Methane and Ethane
Ozone depletion happens in the _______. Global warming happens in the _________.
Stratosphere.
Troposphere.
It is illegal to vent CFC and HCFC refrigerants as of
July 1, 1992
What type of refrigerant is classified as “natural refrigerants”?
HC refrigerants. Example: Propane
What is the visual indicator that a system uses flammable refrigerant?
There should be flammable hazard signs on the plates near the compressor/ evap. Service lines are also painted red
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.
Along with diagram, choose appropriate valve position for each valve in system
Calculate recovery cylinder capacity. Using formulas.
Be mindful of DOT stamping. 4BA”350” not acceptable
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?
36.4 psig based of PT chart
High side pressure gauge reads 114 psig. At what temperature is the R134a refrigerant changing back to liquid inside the condenser?
95 degrees F based on PT chart
The ambient temperature near a standard fin and tube condenser is 95F. What is the condensing temperature inside?
125 degrees F
Never exceed the design _________ side factory test pressure on the name plate when pressurizing a system with nitrogen
Low
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?
The difference in operational pressures may result in evaporator leaks.
TXV may also need adjusting.
What type of refrigerant blend is a long-term replacement for HCFC blends?
HFC refrigerant
Pressure relief valves should always be installed in ________ with one another, never in series
parallel
