3e151 B Set Vol 4

100 Questions | Total Attempts: 604

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CDCs Quizzes & Trivia

UREs for B set of 3E151 cdcs Vol 4.


Questions and Answers
  • 1. 
    In air distributions systems, the three basic categories of fans are
    • A. 

      Backward inclined, airfoil, and forward curve

    • B. 

      Radial blade, centrifugal, and tubular inline

    • C. 

      Centrifugal, special design, and axial

    • D. 

      Propeller, tubeaxial, and vaneaxial

  • 2. 
    What are the width and inlet constructions of centrifugal fans?
    • A. 

      SWSI and DWDI

    • B. 

      SWDI and DWSI

    • C. 

      SPST and DPDT

    • D. 

      SPDT and DPST

  • 3. 
    The purpose of the vanes of a vaneaxial fan is to
    • A. 

      Change the fpm

    • B. 

      Change the cfm

    • C. 

      Increase the torque

    • D. 

      Straighten out the air's spiraling motion

  • 4. 
    A fan drive is an assembly made up of
    • A. 

      A motor sheave, fan sheave, and connecting belts

    • B. 

      Grooves used to increase and decrease the speed of the fan

    • C. 

      Fixed bores that allow the sheaves to fit the shaft exactly

    • D. 

      Movable discs to increase or decrease the pitch diameter

  • 5. 
    To prevent needless problems to your heating, ventilation, air conditoner, and refrigeration (HVAC/R) equipment, which items should you check during V-belt inspections?
    • A. 

      Outside diameter

    • B. 

      Proper alignment

    • C. 

      Pitch length

    • D. 

      Belt alignment

  • 6. 
    The most common size of V-belts used in HVAC systems are
    • A. 

      1L, 2L, and 3L

    • B. 

      3L, 4L, and 5L

    • C. 

      A through D

    • D. 

      A and B

  • 7. 
    What is generally the proper tension for the top side of fan belts?
    • A. 

      1/2 to 1 inch deflection

    • B. 

      1/2 to 1 1/2 inch deflection

    • C. 

      3/4 to 1 1/4 inch deflection

    • D. 

      3/4 to 1 3/4 inch deflection

  • 8. 
    A single-duct system become a low-pressure reheat system when
    • A. 

      A higher-pressure duct design and pressure reduction devices are used to permit system balancing

    • B. 

      Heating coils are inserted into the duct system downstream of the cooling coils

    • C. 

      The system responds to only one set of space conditions

    • D. 

      Excess air is dumped into a return-air ceiling plenum

  • 9. 
    The individual zone or space control is provided in an indution system by
    • A. 

      Heating and secondary airstream

    • B. 

      Careful analysis of the system

    • C. 

      The low-pressure reheat coils

    • D. 

      Inducting the sir

  • 10. 
    Which multiple-path system uses a mixing valve to control zone temperature by mixing warm and cold air in proper proportion?
    • A. 

      Multizone

    • B. 

      Dual-duct

    • C. 

      Dual-reheat

    • D. 

      Variable-air-volume

  • 11. 
    What is one way to reduce energy costs if a dual-duct system with no cooling load?
    • A. 

      Replace existing boxes with high-pressure boxes

    • B. 

      Operate the system as a single-zone

    • C. 

      Operate the system as a multizone

    • D. 

      Eliminate the return-air fan

  • 12. 
    Which multiple-path system meets requirements of the different zones by mixing cold and warm air through dampers at the central HVAC unit?
    • A. 

      High-velocity, dual-duct

    • B. 

      Low-velocity, dual-duct

    • C. 

      Multizone

    • D. 

      Induction

  • 13. 
    The supply pressure loss data for equipment used in piping systems normally come from
    • A. 

      Manufacturers

    • B. 

      System designers

    • C. 

      HVAC/R technicians

    • D. 

      Velocity head pressure

  • 14. 
    What is static head?
    • A. 

      Pressure in psi being pumped representing system resistance that must be overcome

    • B. 

      Pressure due to the weight of the fluid above the point pf measurement

    • C. 

      Sum of the lift and velocity head at the pump

    • D. 

      Positive head minus friction head

  • 15. 
    How many intakes does the single-suction pump impeller have?
    • A. 

      One

    • B. 

      Two

    • C. 

      Three

    • D. 

      Four

  • 16. 
    Which type pump casing collects water from the impeller and discharges it parallel to the
    • A. 

      Multiple

    • B. 

      Volute

    • C. 

      Diffuser

    • D. 

      Single

  • 17. 
    Some leakage at the packing gland of a pump is needed to
    • A. 

      Equalize the pressure on the two sides of the seal

    • B. 

      Seal undesirable leakage to the stuffing box

    • C. 

      Allow the coupling halves to be disconnected

    • D. 

      Lubricate and cool the area between the material and shaft

  • 18. 
    Pumps with mechanical seals 
    • A. 

      Can be run dry, depending on the ambient temperature

    • B. 

      Can be run dry, depending on the internal pressure

    • C. 

      Must not be run dry

    • D. 

      Must be run dry

  • 19. 
    Destructive pitting and wearing of a pump impeller and casing as well as noise and vibration can be caused
    • A. 

      Cavitation

    • B. 

      Friction loss

    • C. 

      Stratification

    • D. 

      Flow coefficient

  • 20. 
    What is normally the cause of vortex in a piping system?
    • A. 

      Undersized piping

    • B. 

      Too many fittings

    • C. 

      Location of the pump

    • D. 

      Configuration of the piping system

  • 21. 
    What do manufacturers use to show how pumps respond under different operating condidtions?
    • A. 

      Curves of system pressure changes for different altitudes

    • B. 

      Curves of the temperature and pressure limitations

    • C. 

      A graph of net positive suction pressure head curves

    • D. 

      A performance curve graph

  • 22. 
    After each major repair to a pump or when there is an indication that the system flow is not correct, what do you check?
    • A. 

      Pump performance

    • B. 

      Mechanical seals

    • C. 

      Stuffing box

    • D. 

      Bearings

  • 23. 
    What is the maximum allowable working pressure for low-pressure heating boilers with a maximum temperature limitations of 250*F?
    • A. 

      140 psi

    • B. 

      160 psi

    • C. 

      180 psi

    • D. 

      200 psi

  • 24. 
    What is the usual pressure or medium-pressure heating when the usual design supply temperature is approximately 250*F to 350*F?
    • A. 

      140 psi

    • B. 

      150 psi

    • C. 

      160 psi

    • D. 

      180 psi

  • 25. 
    What is the maximum allowable working pressure for high-pressure heating boilers with a maximum temperature limitation of 450*F?
    • A. 

      180 psi

    • B. 

      200 psi

    • C. 

      250 psi

    • D. 

      300 psi

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