Topics: All categories in the pool
1: Which of the following are considered inorganic refrigerants?
- R-717 and R-718
- 410A and R-407C
- R-500 and R-502
- None of the above
2: What is specific heat?
- measured heat
- heat required to raise the temperature of 1lb of a substance 1 degree
- the specific heat required to change the state of one cubic foot of air to steam
- none of the above
3: How does a centrifugal compressor create the pressure differential needed to move refrigerant through the system?
- Suction and discharge valves
- Rotating vanes
- Fan-like action
- Nesting scrolls
4: Low ambient controls are used when
- when systems run all year round
- always
- economizers are used
- on air conditioning systems only
5: If a refrigerant leaving the condenser is 94F and the condensing temperature is 105F, the subcooling is
- 29F
- 9F
- 21F
- 11F
6: The measurement of heat in a particular substance is
- latent heat
- enthalpy
- sensible heat
- specific heat
7: A class B1 refrigerant is considered
- non-toxic and non-flammable
- non-toxic but highly flammable
- toxic and somewhat flammable
- toxic but non-flammable
8: Ohm's Law indicates Amps X Resistance = ___________.
- Impedance
- Current
- Ohms
- Volts
9: How are safety controls wired in a circuit?
- Either series or parallel
- Series
- Series/parallel
- Parallel
10: A single pole-double throw switch used how many wires excluding the ground wire?
- three
- two
- five
- four
11: What is absolute humidity?
- the amount of moisture in the air per one pound of 50% RH air
- the amount of moisture in the air in grains of cubic feet of volume
- the amount of moisture in the air in grains of square feet of volume
- none of the above
12: If the dry bulb temperature is 85F and the wet bulb temperature is 70F, the dew point temperature will be approximately (use psychometric chart)
- 77F
- 70F
- 32F
- 58F
13: If your suction line is warmer than the room temperature, this may indicate
- a low charge
- an over charge
- below normal superheat
- plugged air filter
14: What is not a requirement of a class T machine room?
- fire hose connection to the building fire protection system
- tight fitting doors
- automatic ventilation
- self-closing doors
15: A compressor that increases vapor pressure by changing the internal volume of the compression chamber is called?
- Pressure induced displacement.
- Positive displacement
- Non-positive displacement
- Low Pressure displacement
16: Megaohm meter's main function is
- to detect weak motor winding insulation of a refrigeration or air conditioning compressor by creating high DC voltages to the compressor
- to detect very high resistances to ground of refrigeration or air conditioning compressors
- to test very high value capacitors for large 3-phase refrigeration compressors and blower motors.
- Both a and b are correct
17: Where a refrigeration or air conditioning system is installed,
- it shall not be operated below prescribed pressuers
- A field inspection shall be made before it is put into service
- The company who installed the system must notify the fire department in the jurisdiction where installed
- the form or certificate shall be authorized by the Department of Public Safety
18: When an A/C system is excessively low on refrigerant
- it can become contaminated with water
- there can be nuisance trip outs
- the suction line may be too hot to touch
- All of the above
19: There can be no airflow from an occupied space through a machine room unless what?
- System is high velocity
- System is ducted and sealed
- Duct is not located in the ceiling
- None of the above.
20: Group A1 refrigerants over ____ pounds in a system must discharge to the atmosphere
- 330
- 110
- 6.6
- 1,000
21: Class A refrigerants are considered
- toxic
- non-flammable
- non-toxic
- flammable
22: A pressure vessel having an inside diameter of 6” or less shall be sufficient to withstand ____times the pressure of the saturation temperature of the refrigerant or ____times the critical pressure of the refrigerant, whichever is less.
- 2.5, 3.0
- 3.0, 3.5
- 6.6, 6.6
- 2.5, 2.5
23: The outer portion of shell of the compressor used on low-pressure chillers is called the
- volute
- suction
- nozzle
- baffle
24: A hissing noise at the expansion valve is a good indication that
- expansion valve is oversized
- gas is passing thru it
- nothing is passing thru
- liquid is passing thru it
25: 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