• Home
  • Download PDF
  • Order CD-ROM
  • Order in Print
Figure 4   Rotary Lobe Air Compressor
Hazards  of  Compressed  Air

Mechanical Science Volume 2 of 2
Page Navigation
  61    62    63    64    65  66  67    68    69    70    71  
AIR COMPRESSORS DOE-HDBK-1018/2-93 Miscellaneous Mechanical Components Centrifugal  Compressors Figure 6   Simplified Centrifugal Pump The   centrifugal   compressor,   originally built to handle only large volumes of low pressure   gas  and  air  (maximum  of  40 psig),  has been developed  to enable  it to move large volumes of gas with discharge pressures  up  to  3,500  psig.     However, centrifugal   compressors   are   now   most frequently  used  for  medium  volume  and medium   pressure    air   delivery. One advantage  of  a  centrifugal  pump  is  the smooth discharge of the compressed air. The   centrifugal   force   utilized   by   the centrifugal  compressor  is  the  same  force utilized by the centrifugal pump.   The air particles  enter  the  eye  of  the  impeller, designated    D    in    Figure 6. As    the impeller rotates, air is thrown against the casing   of   the   compressor. The   air becomes compressed as more and more air is thrown out to the casing by the impeller blades. The air is pushed along the path designated A, B, and C in Figure 6.   The pressure of the air is  increased  as  it  is  pushed  along  this  path.   Note  in  Figure  6  that  the  impeller  blades  curve forward,  which  is  opposite  to  the  backward  curve  used  in  typical  centrifugal  liquid  pumps. Centrifugal  compressors  can  use  a  variety  of  blade  orientation  including  both  forward  and backward curves as well as other designs. There may be several stages to a centrifugal air compressor, as in the centrifugal pump, and the result would be the same; a higher pressure would be produced.   The air compressor is used to create  compressed or  high pressure air  for a variety  of uses.   Some of its  uses are pneumatic control devices, pneumatic sensors, pneumatic valve operators, pneumatic motors, and starting air for diesel engines. Compressor  Coolers The amount of moisture that air can hold is inversely proportional to the pressure of the air.  As the pressure of the air increases, the amount of moisture that air can hold decreases.  The amount of  moisture  that  air  can  hold  is  also  proportional  to  the  temperature  of  the  air.     As  the temperature  of  the air  increases, the  amount  of moisture  it can  hold  increases.   However, the pressure change of compressed air is larger than the temperature change of the compressed air. This causes the moisture in the air to condense.   Moisture in compressed air systems can cause serious  damage.    The  condensed  moisture  can  cause  corrosion,  water  hammers,  and  freeze damage; therefore, it is important to avoid moisture in compressed air systems.  Coolers are used to minimize the problems caused by heat and moisture in compressed air systems. ME-05 Rev. 0 Page 6







Western Governors University

Privacy Statement
Press Release
Contact

© Copyright Integrated Publishing, Inc.. All Rights Reserved. Design by Strategico.