How to design an orifice plate

  1. Hello everybody

    Its Bashir .. I am doing a research on Upflow floating media filte and have some questions and kindly ask u to help me
    :I will explain to u what I am going to do exactly

    1) I have to built a filter pilot plant for water treatment ( its my research )

    This filter will be around 2 or 3m in length and 300mm in diameter.. and i will test this filter in removal impurities from water.. of course i will connect this filter with feed water tank by using PVC pipes.. and will test different flow rater and will add some chemicals by using dosing pupm...

    My question is:

    1- i was thinking that the flow rate will change once its mixed with chemicals from the dosing pump .. so we decided to design an orifices plats and conncect them at certain positions on the pipes to keep the flow rate constant..


    2- But to be honest: i really do not know exactly about the orfice and how it works and why we need to use it ?

    3- Could u just explain to me ? and why the flow rate will change if we control it ..

    4- what is the basics of design an orifice ?say for example i will use pipes with 30, 40mm in diameter for water flow to the filter and flow rate will be 170 to 300 L/H... and the velocity will be 2.5 and 5 m/h...

    5- So how can i make a design for an orifice plate and where should i put it ?

    Please try to answer my questions... I really need your help

    Bashir Brika
     
  2. jcsd
  3. stewartcs

    stewartcs 2,279
    Science Advisor

    Hello Bashir,

    IIRC, the flow rate shouldn't change if the pump is capable of maintaining its designed flow rate. However, if the fluid density changes drastically as a result of adding the chemicals it might reduce it by overloading the pump.

    Orifice plates are used for various reasons. Some include, reducing or increasing line pressure, decreasing flow rates, etc...

    One effect of an orifice plate will depend on the maximum flow rate the orifice is capable of flowing. For example, if used in a pumping system, and the maximum flow rate of the orifice is less than the flow rate of the pump, the pump will build a backpressure upstream of the orifice while reducing the flow rate downstream of the orifice.

    Here are some links to help you out:

    http://en.wikipedia.org/wiki/Orifice_plate

    http://www.efunda.com/formulae/fluids/calc_orifice_flowmeter.cfm

    http://www.flowmeterdirectory.com/flowmeter_orifice_calc.html

    Hope this helps.

    CS
     
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