A simple capacity control method that provides capacity steps of 25 percent, 50 percent, and 75 ...

A simple capacity control method that provides capacity steps of 25 percent, 50 percent, and 75 percent using
  a plug valve would be found on a _____.
 
  a. scroll compressor
  b. hot gas bypass valve
  c. screw compressor
  d. rotary compressor

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[Ques. 2] Purging refrigerant lines with nitrogen during their installation prevents _____.
 
  a. acid formation
  b. overheating
  c. copper oxide formation
  d. corrosion buildup

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[Ques. 3] Throttling valves are used for capacity control on a _____.
 
  a. scroll compressor
  b. reciprocating compressor
  c. centrifugal compressor
  d. screw compressor

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[Ques. 4] A stationary vane can be found in a _____.
 
  a. scroll compressor
  b. rotary compressor
  c. screw compressor
  d. centrifugal compressor

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[Ques. 5] What capacity control method is popular with open and semi-hermetic reciprocating compressors?
 
  a. Slide valves
  b. Cylinder unloading
  c. Plug valves
  d. Throttling unloaders