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How to Calculate Airflow from Aquarium Tubing and Pump?

I have a pond pump and standard aquarium plastic tubing. I will be drilling tiny holes in equal increments throughout the tubing to release the air. Is there an equation to show the air pressure that will be released through the holes? I would like to know how many holes I need and how far to space them to achieve a certain amount of air pressure to be released from a specified length of tubing.This is a test and will not be done under water. A simple diffuser will not work for this application.Ideally I would like a formula where I can input the following and get a result:Tube LengthTube DiameterPump PSITube Hole SizeTube Hole QuantityTube Hole SpacingResultAirflow per Tube HoleAny help would be greatly appreciated. If you need more information please let me know.Thank you,


The flow rate under water will be quite different from the rates in air. Unless all holes are at the same horizontal level the flow rates will vary. As a general rule, the total cross sectional area of all holes must be below 14% of the cross sectional area of the tube to ensure equal flow from each hole along a long length of tube. Along with the pump PSI (What sort of pump? Diaphragm, piston, centrifugal?) the maximum out put is also a factor. If it is a positive displacement pump the full capacity will be distributed through whatever holes are available with the pressure increasing to achieve this.. hyperphysics.phy-astr.gsu.edu/Hba...
Well, I suppose it could be done, but you would need the pressure at each hole,which is decreasing as the tube length and water depth. And you have so many variables! I also like to calculate such things as you are doing, but this is really over the top! Here is what I would do; Get a measured paper cup (say 1 cup, or 1/4 litre). Experiment with various sizes and number of holes in your tubing, then hold the cup over the coiled tubing, under water at required depth, with air pump running. Measure the time to fill the inverted cup with air. If a 1/4 litre container fills with air in 15 seconds (1/4 minute), you know you are getting 1 litre per minute. Then try other hole configurations to get what you want. This would be more fun, more practical, and will give bettter results. Good luck Bill

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