Topics: All categories in the pool
1: An example of direct system is
- rooftop unit
- chiller
- absorber
- none of the above
2: 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
3: Total heat of a substance is considered
- specific heat
- empathetical
- enthalpy
- sensible heat
4: When a receiver is greater than 3 cubic feet but less than 10 cubic feed, what is the minimum relief device required?
- fusible plug
- relief valve
- rupture disc
- all of the above
5: Whoever owns/uses a refrigeration or air conditioning system covered by this code
- must notify the Department of Public Safety prior to starting the system
- shall be licensed by the Commonwealth of Massachusetts according to CMR 522
- shall make application for inspections to the Chief of Inspectors
- None of the above
6: What is the temperature that a liquid and a vapor can exist in equilibrium called?
- Saturated temperature
- Wet bulb temperature
- Critical temperature
- Dry bulb temperature
7: On cooling towers, what causes the condenser water to drop
- tower fans
- sensible heat
- evaporation of the water droplets
- ambient temperatures
8: Low pressure chiller systems use what type of compressor?
- Screw
- Scroll
- Centrifugal
- Reciprocating
9: Industrial occupancy is
- a premise or that portion of a premise that is not open to the public, where access by authorized persons is controlled, and that is used to manufacture, process, or store goods, such as chemicals, food, ice, meat, or petroleum.
- is a premise or that portion of a premise where large number of people congregate and from which occupants cannot quickly vacate the space.
- a premise or that portion of a premise where people transact business, receive personal service, or purchase food and other goods.
- Both a and b are correct
10: Watt's Law indicates Volts X Amps = _________.
- Resistance
- Watts
- Ohms
- Current
11: In an air conditioning system, the unit of total heat energy content in an air/vapor mixture is
- Specific heat
- Latent heat
- Enthalpy
- Sensible heat
12: What type of voltage causes the winding in a potential relay to open?
- BEMF (Back Electro-Motive Force)
- 24V control voltage from the thermostat
- 120V line voltage
- None of the above
13: 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
14: A self contained system
- is a unit system Group II refrigerants only
- is a unit system Group I refrigerants only
- is a complete factory made and tested system
- is any system or part of a system used to increase evaporation by expansion or vaporization
15: Gauge pressure is
- Atmospheric pressure
- Absolute pressrue
- Barometric pressure
- Force of pressure above that of atmosphere
16: When a refrigeration or air conditioning system is installed
- a field inspection shall be made before it is put into service
- it shall not be operated below prescribed pressures
- the form of certificate shall be authorized by the Department of Pubic safety
- it shall be approved by the owner for proper operation.
17: The maximum permissible amperage draw for a 40VA transfomer with a secondary voltage of 24V is
- 1.7
- .8
- .1
- 1.2
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: A class B1 refrigerant is considered
- non-toxic and non-flammable
- non-toxic but highly flammable
- toxic and somewhat flammable
- toxic but non-flammable
20: What is a Category "D" fluid?
- A typical refrigerant used on newer air conditioning and heat pump ssytems
- A toxic fluid, which can produce serious irreversible harm to persons on breathing or bodily contact
- Any fluid that exceeds 150 psig and has design temperature of over 366F
- A fluid which is nonflammable, nontoxic, not damaging to human tissues, does not exceed 150 psig, and design temperature is between -20F to 366F
21: On a single phase motor, when does the start winding cut out?
- At 25% of its full rated speed
- At 50% of its full rated speed
- Start windings do no cut-out of the run cycle
- At 75% of its full rated speed
22: What will occur if the strong solution in an absorption chiller becomes too strong?
- The machine will cool excessively as the solution crystallizes.
- The machine will stop cooling and the solution will evaporate.
- The machine will cool excessively as the solution evaporates
- The machine will stop cooling and solution will crystallize
23: Heat that changes the physical state of a substance without effecting a change in its temperature is known as
- specific heat
- sensible heat
- lost heat
- latent heat
24: Which of the following most closely represents the concentration of Li-Br in a absorption system?
- 60% Li-Br, 40% distilled water
- 40% Li-Br, 60% tap water
- 40% Li-Br, 60% distilled water
- 50% Li-Br, 50% tap water
25: In a properly balanced system with valves open and properly adjusted, if the suction line is warm to the touch, its because of
- not enough oil in the system
- moisture in the system
- low head pressure
- oil in evaporator