Anyone versed in fluid dynamics ?

Discussion in 'Pumps and Waterflow' started by Sammy, 17 Oct 2012.

  1. Sammy

    Sammy

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    Would like some advice on 8600 l p/h through a 25mm pvc piping. Would you recommend or will I be restricting too much and putting pressure on the pump.

    Pump in question is the Sicce 9000e

    Thanks in advance.
     
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  3. mariusmeyer

    mariusmeyer

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    You will get better throughput by using 2 lines instead of one.
     
  4. OP
    Sammy

    Sammy

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    @mariusmeyer, thanks I do have two lines, buy you have to split it ? so its going 1 to 2 ?
     
    Last edited by a moderator: 26 Nov 2015
  5. NADEEM

    NADEEM

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    1 to 2 is fine, i dont remember anything of the few fluid dynamics subjects i did lol, but yeah def 2 line, 1 to 2 will work ok
     
  6. OP
    Sammy

    Sammy

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    but wont the flow be restricted before the split ?
     
  7. mariusmeyer

    mariusmeyer

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    As long as the piece before the split is not that long it should not cause that much loss. And using a Y splitter instead of a T piece will also give you less back pressure.
     
  8. rakabos

    rakabos

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    That is a LOT of flow for 25mm

    I had problems with 4000lph on 20mm so i imagine you will have also
     
  9. NADEEM

    NADEEM

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    awesome advice
     
  10. AndrewR

    AndrewR

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    For a flow of 8600 lph

    Calculations give you a fluid velocity of 4.86 m/s flowing through your 25 mm pipe. The most economic velocity for water through a pipe is between 2 - 3 m/s.

    Further calculations give you a friction head loss (pressure drop ) of 1,51 m (~ 150 cm) per 1 m of pipe length at this velocity.

    e.g. this means that if your return pipe is approximaetly 2 m in length and height you would have a total pressure loss of 2m + 2(1,51m) = 5 m. (This is massive head loss)

    Using the formuale

    p1/p2 = (q1/q2)^2

    where p = pressure (m)
    q = flow (lph)

    one can calculate the return flow at your subsequent head loss.

    Its not wrong to use a 25 mm pipe it just gives you a higher pressure loss in your pipe and a decreased volumeteric flow into your tank.

    What marius says is correct by splitting your pipes you split your flow giving a lower velocity in each pipe and therefore a smaller head loss and greater flow into your tank.

    Cheers
     
    Last edited: 17 Oct 2012
    Sammy likes this.
  11. Bob the (reef)builder

    Bob the (reef)builder

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    Nice answer AndrewR. I would definitely use bigger pipe myself. At least 32mm.
     
  12. OP
    Sammy

    Sammy

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    Wow, thanks a stack, so you say its "ok" to use 25mm, I don't have much other choices are already plumbed.

    Now my other question all I could find is this 45 deg T, google tells me that flow is split equally however it doesn't look so ? your expert advice again ?

    images?q=tbn:ANd9GcShb2-PybYBChlBNIUMT8Kx-ASZGneJCvrMgIDjkcUfiJpRFMjTkg.jpg
     
  13. rakabos

    rakabos

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  14. mariusmeyer

    mariusmeyer

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    My non expert opinion is to not worry about the non equal split issue.
     
  15. RiaanP

    RiaanP Moderator

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    How many other elbows would be on the line/s?
     
  16. OP
    Sammy

    Sammy

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    one from return and another 2 to make the bend up to the tank then another 2 back into the side glass
     

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