Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

How do I calculate / convert GPM to PSI ?

  1. Aug 31, 2010 #1

    kck

    User Avatar

    Ok I should say up front Im not near as brilliant as you fine folks, I was a C student now Im a Dad that cant figure his 11 year olds homework out :yuck:. I hope someone will be so kind as to help me lol.

    Scenario:
    We are going tuna fishing, so we need a live bait (anchovy) tank. This requires a 30 Gallon plastic rain drum with water flowing in one circular direction to create the needed "current" to make the tuna bait happy. If anchovies are not swimming against current they will die.

    I am guessing around 2 MPH in a circular motion. This will be created by a water pump hooked into a pipe that is mounted vertically in the drum with holes drilled in one side on the pipe hence creating the current.

    My question: Is there a formula for figuring out the needed GPH pump, vertical pipe size, and size needed for the holes in the pipe?
     
  2. jcsd
  3. Aug 31, 2010 #2

    Andy Resnick

    User Avatar
    Science Advisor
    Education Advisor

    I'm having trouble picturing the tank- presumably water also drains out?

    2 miles per hour = 0.9 m/s (more sensible units), and this velocity is basically uniform- if it's the speed of fluid coming out of the hose, and the hose is of reasonable size compared to the tank, you can set up a swirling flow with this speed.

    Say you are using a 1" hose: 0.0005 m^2 of area, 1 m/s flow rate = 0.0005 m^3/s volumetric flow = 8 gallons/minute.

    That's a rough estimate-YMMV.
     
  4. Aug 31, 2010 #3

    kck

    User Avatar

    Just like a 50 gallon drum, but smaller 30 gallon. and I am assuming that the holes size drilled pipe matter too?
     
  5. Aug 31, 2010 #4

    Andy Resnick

    User Avatar
    Science Advisor
    Education Advisor

    Again, I am having a hard time picturing what you have in mind.
     
  6. Aug 31, 2010 #5
    Looked for "water flow chart" and found this which might be a start:
    http://flexpvc.com/WaterFlowBasedOnPipeSize.shtml

    The length, diameter, and resistance of the pipe are important and probably best estimated heuristically. I did some calcs based on our Fire Dept flow charts for different hoses and pumps -- which are way out of your range but might be indicative:
    200 feet of hose with a TFT nozzle will run 125 gpm at:
    125 psi for 1-3/4" hose
    100 psi for 2-1/2" hose
    600 feet of 3" supply hose will deliver 125 gpm at about 28 psi
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook