1. #1
    Junior Member

    Join Date
    Jul 2001

    Default Perhaps someone might know these formula's??

    I've been looking everywhere, but can't seem to find the formula's/equations for things such as... friction loss, GPM output given a specific nozzle diameter/PSI... all that fun stuff. If someone might know any of these formula's, or perhaps even more, I would be most thankful if you could help out.

  2. #2

    Join Date
    Mar 2001


    The best place is a pumps or hydraulics book. I had a ? on calculating pressures for stacked tip nozzles and that is where I found it...for some formulas posted here in forums, check out the stacked tip topic...hope this can help.
    Keep Safe!

  3. #3
    Forum Member

    Join Date
    Feb 2001
    Stillwater OK


    Usually these values are taken as some what an estimate, If you are realy serious about knowing what the ammout is write me back and I will try to help. You will need to know the coefficient of friction for the nozzle along with some other factors. write me back at my personal adress if you need more help. A good hydraulics book is sold by fire Protection Publications written buy Pat Brock. He is a Hydraulics professor at Oklahoma State University and realy knows what he is talking about. If you need more help let me know
    let me know if im not clear


  4. #4
    Senior Member

    Join Date
    Jun 2001
    P.G. County


    the ifsta driver/operator book has a whole chapter on figuring friction loss and different formulas to use.

  5. #5
    Senior Member

    Join Date
    May 2000
    DFW area of Texas


    The formulas are standard and regarding hose, you need to contact the manufacturer and find out what it is for a particular hose. They are different depending on materials used in construction and the construction itself.

    FL = Friction Loss
    NP = Nozzle Pressure
    NR = Nozzle Reaction
    Q = flow rate in hundreds of gpm divided by 100
    L = hose feet in hundreds of feet divided by 100
    C = friction coeffecient
    • 1" = 150
    • 1.5" = 24
    • 1.75" = 15.5
    • 2" = 8
    • 2.5" = 2
    • 3" with 2.5" couplings = 0.8
    • 4" = 0.2
    • 4.5" = 0.1
    • 5" = 0.08
    • 6" = 0.05
    Friction Loss

    FL = C x Q sq. x L

    Smoothbore Flow

    GPM = 29.7 sq. x dia. of the orifice x sq.rt of the NP (pitoted)

    Fog Flow

    GPM = Rated Flow divided by sq rt of rated NP X sq rt. of NP
    It's only my opinion. I do not speak for any group or organization I belong to or associate with or people I know - especially my employer. If you like it, we can share it, you don't have to give me credit. If you don't, we are allowed to disagree too (but be ready to be challenged, you may be on to something I'm not). That's what makes America great!

  6. #6
    Senior Member
    Dalmatian90's Avatar
    Join Date
    Mar 2000


    If you have Microsoft Excel (5.0 through 2000) go to:

    It's the same spreadsheet I use when I come back with my indepth responses

    One of these days I'll figure out how to make a run-time executable out of it so you don't need Excel, but that may be far, far away!
    IACOJ Canine Officer

  7. #7
    Junior Member

    Join Date
    Nov 2000


    Another good source for basic hydraulics is at the Task Force Tips website. It explains nozzles and hydraulics. They'll even send you literature on same or you can download it there. They are great and have a good website.

  8. #8
    Senior Member

    Join Date
    Jul 2001
    South Florida


    OLD Stand-by Trick

    but don't tell anybody you heard from me...

    Use the THUMS school of fire fighting..
    THUMs up mo water
    THUMS down mo less water
    and the classic call over the radio from the IC SHUT DOWN that LINE
    N O W !!!!!!

    and you have 5 lines working at that time...

    The Real art as a Driver,..is to know who's on what line when the call comes out give me more psi...

    who's on first, what's on second,
    and I don't know third base...

    good luck

    [ 07-28-2001: Message edited by: Captain 12 ]

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