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Flow Rate of a Deflation Balloon

  1. Sep 6, 2009 #1
    A drug delivery infusion pump is made out of thick synthetic rubber and has a very small outlet. The balloon pump is filled with 500mL liquid drug and is now inflated into a ball shape. The drug will exit from the very small outlet at a nearly (but not always) constant flow rate of 5mL/hr (takes 100hr to deplete).

    How can I derive the flow rate as a function of time?
    I'd also like to know how the temperature and drug viscosity affect the flow rate.

    Someone suggested me to use Poiseuille-Hagen equation, but I need to know more details, especially how I can relate the flow rate to time and establish a model.

    Your insight will be highly appreciated!
  2. jcsd
  3. Sep 12, 2009 #2
    the flow rate is constant meaning it remains at 5ml/hr until 100hr is surpassed. so i'd be a piecewise function that looks like this:

    given x is time in hours and y is in ml/hr
    if 0<x<100 then y=5
    if x>100 then y=0

    the temperature and viscosity are almost always related in such a manner
    as temperature rises viscosity drops and vice-versa
    and if viscosity drops then flow rate is usually increased.
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