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I General information on back pressure in a syringe

  1. Sep 14, 2016 #1
    Hi all

    I'm looking for general information on "back pressure" specially in a syringe. So when you put your finger over the top of a syringe and depress the plunger then release the pressure on the plunger and the plunger moves back slightly. I'm struggling to find some specific information that will help me explain this scenario? So any reading that you think would be good please provide a link.

    Cheers
     
  2. jcsd
  3. Sep 14, 2016 #2

    BvU

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    Hello Petra,

    Did you notice a difference between syringes filled with air as opposed to syringes filled with water ?
     
  4. Sep 14, 2016 #3
    This syringe is filled with air only and connected to another syringe that is empty. I'm looking for a text reading that will help me understand what is happening, I don't necessary need anything solved just need a good resource that I can refer to.
     
  5. Sep 14, 2016 #4

    BvU

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    Air is compressible: when you increase the pressure (push down the syringe) the volume decreases. The air in the reduced volume presses back.
    When all this is done at approximately the same temperature, the product of air volume (in the two syringes combined) and pressure is constant (Boyle-Gay Lussac law). Google or look it up in an introductory physics textbook.
     
  6. Sep 14, 2016 #5

    Bystander

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    Also, Google "hysteresis." You haven't identified/specified seal type.
     
  7. Sep 26, 2016 #6
    Many thanks to all that have posted.
     
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