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A Flow through IV giving setting

  1. Oct 29, 2016 #1
    I know I am over thinking this but it's bugging me...

    When giving patients fluid through an IV giving set, we set the flow rate by adjusting a rolling clamp on the tubing line. This is in effect creating a construction.

    Reading about flow, I am told over and over that flow is conserved. That is, fluid increases its velocity through a constriction to maintain flow.

    Clearly this doesn't happen when I clamp the tubing - the flow rate decreases...

    I know that Poisuelles law states that flow is directly proportional to radius to the power 4 so that halving r would lead to 16x less flow. But still I though flow was conserved?

    I would really appreciate someone explaining this to me...
  2. jcsd
  3. Oct 29, 2016 #2


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    Staff: Mentor

    I don't know much about fluid dynamics, but I'd guess they mean that the flow through any given hose/tube/whatever is conserved, and that when you change the system, by adjusting the clamp in your case, you create a different system with a different flow rate that is conserved throughout the tube.
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