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Flashcards in Screw Compressors/Lobe Blowers Deck (20)
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1
Q

Rotary positive displacement compressor

A

-

2
Q

Dual rotor

A
  • dry screw is oil free. Some incorporate a water spray within the compression chamber to cool and help seal - the air created can be reused
  • wet screw is oil flooded by injected oil to lubricate the seal and cool the air end
3
Q

Compression cycle

A
  • the male rotor has lobes that mesh with the flutes on the female rotor as they both rotate inside the housing
  • the male rotor is usually the rotor that is directly driven
4
Q

Discharge ports

A

-the wider the discharge port the lower the pressure

5
Q

Built in pressure

A

-difference between the pressure at the inlet and the discharge

6
Q

Pressure ratio

A

-is a ratio of the absolute incoming air pressure to the absolute compressor discharge pressure

7
Q

Volumetric Efficiency

A

-back leakage where compressed air tries to get back through the compressor to the low suction pressure

8
Q

Capacity and discharge

A

-

9
Q

Asymmetrical vs. Symmetrical

A

-show pictures of each

10
Q

Compressor capacity

A

-rotor length, diameter, lobe/flutes design and speed

11
Q

Bearing locations

A
  • fixed (tapered) bearing must be at the discharge end because the clearance has to be held there to hold pressure
  • thrust bearings are required to maintain rotor position relative to the end plates
12
Q

Wet Screw

A

-

13
Q

Dry Screw

A
  • needs timing gears

- able to provide oil free air

14
Q

Air Filters

A

-filters out air born shit to 3-5 microns

15
Q

Load/no load control (online/offline)

A

-throttle the inlet air either full opening the inlet valve or closing depending on pressure desired.

16
Q

Modulation control

A
  • throttles the inlet air valve depending on what is required to adjust the work the compressor needs to do
  • this would be beneficial when the compressor fluctuates between 60-90% capacity
17
Q

Displacement control

A
  • also referred to as geometry control or internal bypass
  • Turn, poppet and slide valves
  • physically changes the opening and creates an opportunity for some of the air to return back to suction without being compressed.
18
Q

Minimum pressure valve

A
  • to build minimum pressure inside the separator to get the oil flowing at start up
  • located at the discharge of the air/water separator
19
Q

Vi (variable volume ratio control)

A

-uses a slide valve to adjust volume as needed

20
Q

Compressors capable of producing clean air?

A
  • lobe blower

- dry screw