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Can a Gear / Vane pump be used for pumping a gas?

  1. Nov 14, 2014 #1
    I have become quite interested in pump physics recently.

    I do a lot of work on cars, this includes work on automatic transmissions. Two main types of pumps I see inside an automatic transmission are the gear pump and the rotary vane pump. In a transmission these pump fluid (also a cars oil pump is typically a gear pump which also pumps fluid)

    My question is, how would these pumps fair in pumping a GAS instead of a liquid? Would they work?

    My guess is they would work but may need to run at a higher RPM to account for the fact that gasses compress a great deal.

    Can anyone provide any insight?

    Thanks to anyone who takes the time to answer!
     
  2. jcsd
  3. Nov 14, 2014 #2

    SteamKing

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    Liquid pumps are not ideal for pumping gases. The liquids which these pumps work with also provide lubrication for the moving parts of the pump. When the liquid is replaced by a gas, you no longer have any lubrication, and the life of the pump is shortened considerably. If you run these pumps at higher RPM in order to pump the gas, the moving parts will wear out even faster.

    Think about what happens when you try to pump the liquid out of a tank. When the liquid falls below a certain level at the pump suction, air is introduced into the pump and pretty soon, the pump pumps neither liquid nor air very well.

    For moving small flows of gas, like in a lab, diaphragm pumps are pretty popular. For moving larger flows of gas, like sending natural gas from a well across state to a city for a utility, compressor stations are placed at intervals along the pipeline, to compress the natural gas and then let it flow and expand until it reaches the next compressor station.
     
  4. Nov 14, 2014 #3
    Ah that makes sense! Thanks for your response! I think that was all I was looking for. :D
     
  5. Nov 14, 2014 #4

    Q_Goest

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    While I'd generally agree with SteamKing, I'd point out that vane type machines are used quite a bit for gasses. They're used for both vacuum and compression but only to relatively low pressure (ie: less than 100 psi). I haven't ever seen a true "gear pump" used for gas though. The problem with both of these designs is sealing the ends of the rotating vane or gear. The vane can seal fine on the circumference but not so well at either end. Gears don't seal well at all so they are generally limited to liquids. What you'll find is that every style of compressor or pump has a market niche that it does well in based on performance, longevity and economics. These are all very general statements - you'll find considerable overlap in the markets for each type of compressor or pump.
     
  6. Nov 14, 2014 #5

    jack action

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    Vane superchargers have been used on cars.

    If a roots supercharger is not the same as a gear pump, it looks a lot like it:

    http://www.turbochargerexplained.com/wp-content/uploads/2014/03/roots_action-262x300.jpg [Broken]
    29966450131c16cb029dd6c82195107b84377f98_large.jpg
     
    Last edited by a moderator: May 7, 2017
  7. Nov 30, 2014 #6
    Isn't this similar to mazdas rotary engine?
     
  8. Nov 30, 2014 #7

    Danger

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    Not even close, other than both contain rotating components.
     
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