AHR-110 Exam 3 Study Guide
A ¼ inch service hose will only allow a vacuum pump to pull at _____ CFM, regardless of the pump's CFM rating.
0.8
It is estimated that a single chlorine atom can destroy up to ______ ozone molecules.
100,000
A service technician is charging an R-410A air-conditioning system that has a TXV metering device. The high-side saturation pressure is 365 psig and the unit's technical manual specifies 10°F of liquid subcooling. What would the desired liquid-line temperature be at the outlet of the condensing unit?
100°F
A technician is working on an R-404A refrigeration system and determines that the head pressure is 205 psig and the condenser outlet temperature is 80°F. The technician correctly concludes that the amount of condenser subcooling is
10°F.
A technician is working on an R-404A refrigeration system and determines that the suction pressure is 30 psig and the evaporator outlet temperature is 10°F. The technician correctly concludes that the amount of evaporator superheat is
13°F
The total phaseout for all HCFC refrigerants is scheduled for the year
2030
The numeric series used for zeotropic and near-azeotropic refrigerant blends are the ________.
400's
A system that contains less than ______ of refrigerant does not require a leak to be repaired, but it is recommended to do so.
50 lb
Atmospheric pressure, 0 psig, is the equivalent of about __________ microns.
760,000
If the components of a binary refrigerant blend have saturation temperatures of 35°F and 42°F at a pressure of 120 psig, what is the approximate temperature glide associated with this refrigerant?
7°F
Which of the following conditions requires a system cleanup, an oil test, and oversized filters to be added to the system?
A compressor motor burnout
A large refrigeration system that contains a significant amount of moisture should be evacuated with
A high CFM vacuum pump
An oily dust spot on a condenser or evaporator coil could indicate
A refrigerant leak
Which of the following terms would be an example of a refrigerant with no temperature glide?
A single-compound refrigerant
The safest overall rating with respect to both toxicity and flammability is
A1
The standard that a refrigerant must meet after it has been reclaimed is
AHRI 700
The standard that a refrigerant must meet after it has been recycled is
AHRI 740
The term used to describe a recovery process that uses a self-contained recovery unit is
Active
Recovery that can capture the entire system charge and pump it into a tank is known as ___________.
Active Recovery
When adding refrigerant to a newly evacuated system, which of the following is the best method?
Add liquid refrigerant to the system through the liquid-line service valve
Moisture, acid buildup, and copper plating can all be caused by which of the following?
Air in the System
What is the difference between an oxygen molecule and an ozone molecule?
An oxygen molecule has two oxygen atoms, while an ozone molecule has three.
The service valve position that is used for normal system operation and closes the gauge port is the ___________ position.
Back-Seated
Before a full graduated charging cylinder is used to charge a system, it should be
Calibrated based on the cylinder pressure.
Proper maintenance for a vacuum pump would include which of the following?
Changing the oil as often as necessary
CFCs are more harmful to the stratospheric ozone layer than HFCs because CFCs contain
Chlorine
Which of the following represents a complete list of the elements contained in CFC refrigerants?
Chlorine, Fluorine and Carbon
Tropospheric ozone is
Close to the earth and is often referred to as bad ozone or smog.
Leaks that require two or more conditions in order to induce leakage are known as
Combination-Dependent Leaks
When charging an air-conditioning system that is operating with a thermostatic expansion valve, which of the following is used as the primary guideline to ensure that the system is properly charged?
Condenser sub cooling
Refrigerant released while making good-faith attempts to recapture and recycle or safely dispose of refrigerant including releases that occur when connecting or disconnecting hoses is called _____________.
De Minimus
Two types of evacuation methods used by technicians are
Deep vacuum and triple evacuation.
Removing air and/or other noncondensable gases from a system using a vacuum pump is called ___________.
Degassing
The most accurate type of gauge for measuring a deep vacuum is a
Digital Micron Gauge
All of the following tasks are part of a refrigerant retrofitting process except
Ensure that the evaporator fan motor is off during system charging.
HFC-based refrigerant blends perform best with a(n) _________ lubricant.
Ester
The most common type of refrigeration oil used in conjunction with HFC refrigerants is
Esters
The process of removing both noncondensable gases and water vapor is called ________.
Evacuation
As a system is charged with vapor refrigerant, the refrigerant tank will likely
Experience a pressure drop and a temperature drop.
(T/F): All 500-series refrigerant blends have temperature glide and have the potential to fractionate.
False
(T/F): The process of a solid changing to a vapor without passing through the liquid state is called dehydration.
False
(T/F): The tare weight of a recovery tank is the weight of the tank if it were filled with water.
False
(T/F): When hot water is used to raise the pressure of a refrigerant tank, the water temperature should not exceed 120° F.
False
A ___________ can remove any type of foreign matter that enters a refrigeration system.
Filter Drier
When a portion of a refrigerant blend evaporates or condenses before the rest of the same blend, what is occurring?
Fractionation
When the stem of a king valve is turned completely clockwise, closing the liquid line, it is in the _____________ position.
Front-Seated
An increase in the natural greenhouse effect that leads to the heating of the earth is called
Global Warming
A DOT-approved refrigerant recovery cylinder is color-coded
Gray with a Yellow Top
Which of the following classes of refrigerants is potentially dangerous because of its high flammability?
HC
Which of the following sets of refrigerant classifications has a zero ODP?
HFOs and HFCs
Which of the following represents a complete list of the elements contained in HFC refrigerants?
Hydrogen, Fluorine and Carbon
Which of the following represents a complete list of the elements contained in HFO refrigerants?
Hydrogen, Fluorine and Carbon
The willful purging or venting of certain refrigerants to the atmosphere is
Illegal as set forth by EPA regulations.
When checking for a leak in the evaporator coil, the leak detector can be placed
In the drain outlet
The term "blend" refers to a refrigerant thatThe term "blend" refers to a refrigerant that
Is made up of two or more different refrigerants.
Standing, pressure-dependent, temperature-dependent, vibration-dependent, combination-dependent, and micro are all types of
Leak Methods
HFO refrigerants are classified as having
Low GWPs and low ODPs.
Which of the tools used during the evacuation process can be wireless and use Bluetooth technology?
Micron Gauge
A deep vacuum can most accurately be measured in
Microns
To perform standing pressure tests and system evacuation, a service valve should be in the ___________ position.
Mid-Seated
When charging a system with vapor refrigerant, what can be done to increase the pressure in the refrigerant tank?
Place the tank in a bath of warm water
When working with blended refrigerants, the refrigerant must leave the cylinder as a liquid to _____________.
Prevent Fractionation
Of the following refrigerants, which is best suited as a retrofit refrigerant for an R-22 residential air-conditioning system?
R-407C
The term used to describe the process of removing refrigerant from a system and surrendering it for reprocessing to meet AHRI 700 standards is
Reclaiming
The term used to describe the process of removing refrigerant from a system and storing it without testing or processing it is
Recovering
The term used to describe the process of removing refrigerant from a system and filtering and/or cleaning it to meet AHRI 740 standards is
Recycling
A _____________ can be used to check the oil composition of a system after a retrofit has been done.
Refractometer
The only two substances that should be circulating in a refrigeration system are
Refrigerant and Oil
Automatic charging capability, auto-stop features, alarms, and wireless remotes are features that are found on some
Refrigerant charging scales.
Low-loss fittings are intended to ensure that
Refrigerant losses are minimized when removing hoses from a system.
When refrigerant leaves a storage tank as a liquid and enters the system as a vapor, what process is taking place between the system and the gauge manifold?
Restricting
The _____________ is both the greatest asset and the greatest liability of an electronic leak detector.
Sensitivity
The term "fractionation" refers to the
Separation of a refrigerant blend into its component parts.
A system that is equipped with a _____________ may require additional steps to ensure that the entire system is evacuated.
Solenoid Valve
The most common type of system leaks are __________ leaks.
Standing
The ____________ method should be used to check the charge of a system equipped with a TXV.
Subcooling
A system equipped with a fixed orifice metering device should be charge using the ____________ method.
Superheat
The term used to describe the range of boiling and condensing temperatures at a given pressure is called ______.
Temperature Glide
The low-pressure side of the system must not be pressurized to more than_________ when testing for leaks.
The low-side design pressure
A system's total refrigerant charge can be found on
The nameplate of a package-type air-conditioning system.
If a refrigerant experiences a temperature glide, which of the following can be correctly concluded?
The refrigerant is a blended refrigerant.
When a deep vacuum is reached (500 microns), the system valved and observed for 10 to 15 minutes. A rise in pressure could indicate which of the following?
There may be a leak or the presence of air and/or moisture
Refrigerants R-11, R-12, and R-22 all have what in common?
They are all methane-based refrigerants.
Which of the following statements is true regarding azeotropes and zeotropes?
They are both refrigerant blends.
How are oil-less compressors on recovery units lubricated?
They rely on residual oil in the recovered refrigerant
What index takes into account the combined effects of global warming potential and ozone depletion potential?
Total equivalent warming impact (TEWI)
The Montreal Protocol is best described as a
Treaty or agreement among nations to address ozone depletion
An evacuation process that is performed a number of times with nitrogen being used to break the vacuum, and ends with a deep vacuum is known as
Triple Evacuation
(T/F): A common term for tropospheric ozone pollution is smog.
True
(T/F): A system with Schrader valve gauge ports will take longer to evacuate than a system with service valves.
True
Which type of EPA Section 608 certification is required to work on small appliances?
Type I
Ozone in the stratosphere protects the earth from ________.
UV-B radiation
A(n) ____________ leak detector requires a lubricant-specific dye be injected into a charged system to find the leak.
Ultraviolet
When leak checking the suction line with an electronic leak detector, the probe should be placed
Under the pipe insulation
What term is used to describe the certification that is awarded when a technician passes all of the parts of an EPA certification exam?
Universal
In order to remove moisture from a refrigeration system using a vacuum pump, it must be in a ____________state.
Vapor
The mechanical strain of motion, rotation, and refrigerant flow are all associated with _________ leaks.
Vibration-Dependent
Leaks that occur only when the unit is in operation are called
Vibration-Dependent Leaks.
One of the advantages of a microfoam leak detection solution over standard bubble solutions is that it
Will not pit or corrode the components
Sludge and other solids can be removed from a system by using __________.
liquid- and suction-line filter/driers
