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How do you run vacuum pumps in series

  1. Dec 5, 2016 #1
    can anyone refer me to a graphical representation of how this works so i can build one?
  2. jcsd
  3. Dec 5, 2016 #2


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    We'll need a bit more information than that before anyone can give a sensible answer .
  4. Dec 5, 2016 #3
    i was watching a video on vacuum forming, the author had built a home made vacuum former with two shop vacs to increase the vacuum pressure. in the comments someone suggested to run the vacuums in series to further increase vacuum. i have a need for stronger vacuum and have several pumps, i need to build a framework to run them in series, i looked into this and can find no illustration of the positioning of the pumps or the airflow, i need to see how it works so i can build the cabinetry to make it work myself.
  5. Dec 5, 2016 #4
    basically i need to see the route the air flows through the pumps
  6. Dec 5, 2016 #5
    to be clear, im not using this to vacuum form, i need the pump for general service
  7. Dec 5, 2016 #6

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    Vacuum pumps don't work this way. There's only so much air that can be taken out, and when it's out, it's out. If you have a pump that will let you get down to a certain pressure, adding a second pump that can also get down to the same pressure will not substantially improve the vacuum.
  8. Dec 5, 2016 #7


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    Running "vacuum cleaners" as opposed to vacuum pumps is an invitation to burn wards; block an air cooled electric motor's source of cooling air and temperatures will rise.
  9. Dec 5, 2016 #8


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    You say you have several "pumps" what type do you actually have?
  10. Dec 6, 2016 #9
    compressors and fans, i was thinking of with the fans, mostly various vacuume cleaner motors
  11. Dec 6, 2016 #10
    thats what i had always thought. but the guy needed more vacuume and he ran two vacs to get it ans some guy claiming to be an engineer suggested to run them in series, i looked into it and got intrigued because i need a better vacuume cleaner to clean up my floors. there seems to be alot on the subject as if it is commonly in practice but i cant find any depictions of it in pictures so i cant understand how theyre saying this works, but they claim there is a substantial increase
  12. Dec 6, 2016 #11
    not the way i invisioned it the second pump would be in the airflow of the first and so it would actually be supercooled but i think the second motor might overheat, i dont know the idea just intrigued me i havent built anything, but i could.
  13. Dec 6, 2016 #12
  14. Dec 6, 2016 #13
    isnt what your referring to as running them in parrelell?
  15. Dec 6, 2016 #14
    thanks for the tip,i didnt realize there was a difference, at any rate, i still am curious as to how it works it seems even more difficult to understand the housing now if it is two compressors
  16. Dec 7, 2016 #15


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    You're misunderstanding the objection. When you run a vacuum cleaner as a vacuum pump, you are cutting off almost all of the airflow. So you have one fan that heats up its tiny airflow a lot, then passes that really hot air to another fan that heats it up even more.
  17. Dec 7, 2016 #16

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    Did I use the word parallel?
  18. Dec 7, 2016 #17
    yes i understand that, i dont think ill make anything like this but i was curious about the design, apparently someones manufactured a machine like this though according to http://www.cleansmartsupplies.co.uk/in-series-versus-airflow-vacuum/ , and id seen a little more on it in other places.
  19. Dec 7, 2016 #18
    no, you described it and used the phrase in series
  20. Dec 7, 2016 #19
    i was just thinking it would be nice to have a better vacuume cleaner, ever try to vacuume sawdust off of carpet? lol, well you all have helped me to better underwstand some principles on the subject, it has been very informative, thanks.
  21. Dec 18, 2016 #20
    The first thing that comes to mind is running one pump in a vacuum chamber that was evacuated by another pump. But then you have no cooling airflow so it wouldn't run long.

    Also this probably wouldn't reduce your ultimate pressure because those pumps already operate at the lower limit of what a rotary-vane pump is physically capable of, assuming you are using that type.

    For mechanical pumps, a lower pressure limit exists because when the pressure is low enough, the mean free path of the gas molecules grows larger than the internal clearances between parts in the pump, and it stops flowing as a gas.
  22. Dec 18, 2016 #21


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    Mechanical turbomolecular pumps need the large mean free path to work.
  23. Dec 18, 2016 #22
    True but I figured for his application, turbomolecular pumps were not on the table.
  24. Dec 20, 2016 #23
    For a souped up vacuum cleaner, wouldn't you want increased air flow rather than lower vacuum pressure? Running them in parallel would make more sense to me, unless I'm missing something.
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