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I need to distribute the water evenly between five holes in my stainless steel pipe. enter image description here

How do i calculate which size the different holes need to be, in order to get the same amount of water out of each hole.

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  • $\begingroup$ You need to constrain the problem further. At a minimum, you need to know the inlet pressure and the desired flow rate. You probably need to know the pipe size also. Example: for high pressure and low flow rate, the holes will be almost the same size (like a lawn sprinkler system). At low pressure and high flow rate, the hole sizes will need to vary quite a bit. $\endgroup$
    – Mattman944
    Commented Sep 13, 2022 at 14:04
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    $\begingroup$ How accurate do you need to be? How is the water being delivered to the pipe? As a first order design strategy, if you keep the pressure in the pipe steady then you can treat each hole in the pipe as an independent orifice calculation because the upstream pressure for each hole will be the same. More details on the whole situation you are analyzing will help get better answers. $\endgroup$
    – J. Ari
    Commented Sep 13, 2022 at 17:25

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Pressurize the supply and then calibrate each nozzle. time the amount each nozzle takes to deliver a given amount.

Adjust each nozzle to match.

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  • $\begingroup$ Clearly this answer comes from an experimentalist :-) . The theoreticians will recoil in horror at the failure to generate a detailed differential equation to predict the required nozzle sizes! [ and the Finance Dept will go berserk at the thought of adding 5 adjustable nozzles to the parts list] $\endgroup$ Commented Sep 13, 2022 at 11:40
  • $\begingroup$ @CarlWitthoft Yes, I did not fancy explaining machining orifices to give a given discharge given how the coefficient of discharge can vary due to the changing pressure drop with length etc $\endgroup$
    – Solar Mike
    Commented Sep 13, 2022 at 12:04
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Every good design engineer knows you cannot design anything without specifications, options, limitations, cost and available materials. I won't give the answer, but I'll give you a hint on how to start with some "specs".

Define the following metrics;

  1. Pipe inner diameter or flow rate with end-open at minimum pressure.
  2. Fluid pressure minimum, at source
  3. Minimum, maximum flow rate per nozzle at min. pressure.
  4. Maximum/min flow ratio for all nozzles (your initial question assumes Rf=1.0)
  5. Purpose
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  • $\begingroup$ This is a comment, not an answer. If you could paste in the fundamental equations which use those parameters, it would become a great answer. $\endgroup$ Commented Sep 14, 2022 at 12:37
  • $\begingroup$ @CarlWitthoft But any answer is pointless until the OP adresses these issues. $\endgroup$ Commented Sep 14, 2022 at 12:53
  • $\begingroup$ @CarlWitthoft , Will it fit into the comments? Did you expect a chapter to explain all the undefined options an conditions? If it was simple, then all the holes see the same pressure and flow., which one can normally assume if the pressure does not drop much. past each hole $\endgroup$ Commented Sep 14, 2022 at 23:02
  • $\begingroup$ When the nozzle diameter is very small relative to the pipe, the loss in pressure, variation is perhaps less than your nozzle variance due to tolerances. $\endgroup$ Commented Sep 14, 2022 at 23:22
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Without more details it can't be calculated, but here is the methodology. For most situations, the flow rate will be about the same for all nozzles.

Pressure loss in pipe from here: https://www.engineeringtoolbox.com/william-hazens-equation-d_645.html I have used this site many times and I believe that it is reasonably accurate.

Nozzle flow rate from here: https://www.azcalculator.com/calc/flow-rate-of-water-from-nozzle.php I have not used this site before, accuracy is unknown. There are other sites that have different formulas for different nozzle types, but they are in metric and I am trying to keep this simple.

Edit the parameters for your situation. Everything is in imperial units (see column C). Pressure drop is per foot. If you get errors in the results, that means that it is impossible to get equal flow rates for the conditions specified.

enter image description here

enter image description here

"Show formulas" enabled: enter image description here

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  • $\begingroup$ "Keep it simple" then work in metric... $\endgroup$
    – Solar Mike
    Commented Sep 15, 2022 at 4:35

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