Topics: All categories in the pool
1: Foaming of oil in a compressor is most likely to occur
- when there is insufficient air across the condenser(i.e., dirty coil)
- when the evaporator temperatures are below 32F
- at start-up
- when ambient temperature are low
2: What happens to copper joints when overheated?
- nothing
- joint becomes oxidized and ditorted
- copper becomes harder
- none of the above
3: The most common type of motor starter is
- part winding starter
- delts-wye starter
- duel-winding starter
- across the line starter
4: The main purpose of a refrigerant detector in a machinery room is to
- inform there is a refrigerant leak int he system
- detect toxins in the air caused by a refrigerant leak
- to set off an alarm when there is refrigerant present inside the room
- all of the above
5: Sensible heat is the heat added to a substance to
- cause evaporation
- raise its temperature
- freeze it
- change its state
6: When energized, a normally open relay will be
- closed
- open
- depends on the type and class of the relay
- noisy
7: R-12. R-22, and R-40 are considered Group I refrigerants.
- True
- False
8: What is the typical air conditioning operating pressures for R-22?
- 60 psi suction 210 psi discharge
- 25 psi suction 125 psi discharge
- 105 psi suction 340 psi discharge
- None of the above
9: Heat that changes the physical state of a substance without effecting a change in its temperature is known as
- latent heat
- lost heat
- specific heat
- sensible heat
10: Joints in piping for refrigeration containing parts must withstand temperatures of ___?
- 1000F
- 800F
- 600F
- 700F
11: A motor starter is a device that includes an overload and a _______?
- contactor
- 2-pole contacts
- duel-coil
- all of the above
12: On a large centrifugal system, what meters the flow to the evaporator?
- Cap tube.
- Low side float
- TXV
- High side float
13: System design pressures must take into consideration, not only, pressures found during normal operation but also what?
- When it's cold out
- When there is a malfunction on the high side
- When its warm out
- All of the above
14: Atmospheric pressure is equal to
- 29.92" Hg
- 14.7 psia
- 14.7 psig
- both a & b
15: A machine room with a refrigerant system using ammonia shall
- be provided with a continuously operated ventilation system
- be considered a non-hazardous location in accordance with National Electrical code
- have no flame producing apparatus permanently installed and operated
- All of the above
16: How many volts would you read on a 480V system phase to phase?
- 480
- 0
- 1/3 the voltage
- 277
17: If two 500 ohm resistors are connected in series, the resistance will be
- 1000 ohms
- 200 ohms
- 20 ohms
- 500 ohms
18: What type of fuses must be used on a HVAC system?
- TR Type, Duel Element, Time Delay
- Fast blow
- 10% lower than RLA
- none of the above
19: Refrigerant restricted in 2004 but used for transition for decades:
- R-22
- R-123
- R-11
- R-134A
20: What chemical in the refrigerant set off the leak detection alarm?
- Fluorine
- Chlorine
- Both A and B
- none of the above
21: When releasing a hydrogenated hydrocarbon refrigerant to the atmosphere, ample ventilation must be provided and
- explosion precautions must be taken
- gas masks must be worn
- no flames shall be permitted
- the owner shall be informed
22: A pressure relief should be located at least _______ from windows and doors.
- 30'
- 20'
- 25'
- 15'
23: An azeotropic refrigerant is
- a mixture of two or more refrigerants that boil at about the same temperature minimizing temperature glide.
- a mixture of two or more refrigerants that boil at much different temperatures causing temperature glide
- a mixture of two or more refrigerants that boil at much different temperatures minimizing temperature glide
- none of the above
24: Where is an EPR valve located on a multi-evaporator system?
- Suction line of the coolest evaporator
- Suction line at the compressor
- Suction line of the warmest evaporator
- Suction line prior to the accumulator of the lowest temperature system
25: Relief valves are rated in
- gallons of water per hour
- pounds of air per hour
- pounds of air per minute
- gallons of water per minute