Operation Maintenance and trouble shooting of chilled-Water air-conditioned systems chapter 49

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Author:
salvatorefricano
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294793
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Operation Maintenance and trouble shooting of chilled-Water air-conditioned systems chapter 49
Updated:
2015-03-01 12:53:56
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unit49 chillers
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star up procedures of chilled water air-conditioning systems, preventative maintenance, chillers-scroll reciprocating centrifugal screw
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  1. A typical chilled water system is desingen to operate with leaving water temperature off the chiller coil at what degree F*
    45*F
  2. who discovered the theory of Absorption systems
    • Michael Faraday
  3. Centrifugal chillers range in size from         tons
    10 to 10,000 tons
  4. On an R-11 or R-123 system, the refrigerant removal process normally starts with the removal of ?
    • Liquid refrigerant
    • push-pull recovery method
    • will speed up process by 150%
  5. A chiller filled control circuit does what?
    • Is a circuit that starts the control procedure before the compressor starts
    • Is often called an interlock system.
    • Ensures that appropriate fans and pumps are started in the proper sequence.
  6. Which of the following is not a large positive displacement compressor
    Centrifugal
  7. water-cooled chillers must have water treatment to do what.
    • minimize mineral and algae deposits
  8. The ideal cooling tower temp of a lithium bromine absorption system is 85*F. What is a likely result if this temp drops to 75*F.
    Crystallization occures
  9. Positive displacement compressors have crankcase heat for what.
    To Prevent refrigerant migration of the compressor.
  10. Tools used to check compressor terminals to ground is called the.
    meg-ohmmeter.
  11. The first step in starting a chilled water system is to
    activate the chilled water circulating system
  12. Low side pressure, converted to a temp
    Evaporator temp
  13. condensing temp(high side gauge reading converted to a temp) -30*F=
    Ambient air
  14. liquid line temp - condensing temp=
                      
                            (high side)
    Subcooling
  15. Boiling temp - suction line temp=

                        (Low side)
    Super heat
  16. (W.C.)(.80)=X+T.W.=
    Max bottle weight
  17. first thing we do on a chiller start up is.
    establish water flow through the chiller barrel and the evaporator.
  18. What must you do 24 hours before start up of the chiller?
    Turn on crank case heater.
  19. What prevents refrigerant migration to the compressor?
    • crank case heater.
    • Belly band
    • internal
  20. What does flow valve do?
    detects water flow.
  21. Witch compressor has an external oil pump?
    • centrifugal
  22. The difference between the oil pump pressure and the suction line pressure of the compressor?
    net oil pressure
  23. For manual pump down witch valve do you have to front seat?
    King valve
  24. The cylinder is moving refrigerant
    loaded
  25. What is meant by Unloading
    • As the load drops the pressure drops.
    • A pressure control activates a solenoid.
    • The suction port is blocked.
    • The cylinder can not pump refrigerant.
  26. one million ohms 
    one hundred thousand ohms
    what must be used to check?
    • good compressor
    • bad compressor internal grounded 
    • mego meter
  27. Large positive displacement chiller?
    scroll, reciprocating, screw
  28. How many pumps in a water cold chiller?
    • 2
    • condenser pump
    •  chiller pump
  29. Screen is located where?
    in the tower
  30. strainer is located where?
    between the sump and the pump
  31. What is used to inspect evaporator tubs for cracks?
    • eddy current tester
  32. Absorption chilled water system start up
    • flow must be established
    • cooling tower must be within design temperature range
    • heat source must be verified
    • monitor the purge unit discharge
    • check the temp drop across circuit {water flow}
  33. Lithium bromide [ LiBi ] is what?
    absorbent that releases the ammonia into the system

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