Thread: Pump Pressure?

  1. #1
    jerseyfire Guest

    Question Pump Pressure?

    There are tons of great information being thrown around by people on this forum about friction loss and stacked tips vs. fog. Where are you all getting your info? Iím looking for one source which gives a good range of info on all angles of pumping and the formerly mentioned topics. What book or web site offers all these calculations?

    Iím also looking to put together some moron proof cheat sheets with gpm flows, friction loss and different tip flows.

    Any help would be appreciated.


    Rob Donnan
    Captain, Metuchen FD
    President, Jersey Fire & Rescue

  2. #2
    Capt. Zada Guest


    To check solid bore knob flows, all that you need is YOUR hose and knob along with a pitot gauge & smooth bore chart. For fog knobs, or the unmentionable nozzle that begins with a "V", you will also need a good flow meter and an in-line pressure gauge. Use the solid bore to determine the friction loss in your hose and to calibrate the flow meter. Be sure that you test and make a chart for each line (individual hose, nozzle, and discharge port combination). Don't use any chart other than the one that you prepare or the circular orifice discharge chart. Test various lengths of hose and chart each. Don't just do 50 or 100 feet and multiply for longer lengths.

    Thirty one years of putting water through the knob has tought me to trust only my own tests. Don't trust any pump, hose, or knob manufacturer's charts and formulas.

  3. #3
    STBURNE Guest


    Capt. Zada hits it right on the head! While waiting to get that equipment however, check out IFSTA Fire Streams 7th ed. and the NFPA HANDBOOK 18th edition. They are good resources and will get you very close. But Capt. Zada is right, trust only your own tests.

  4. #4
    BIG PAULIE Guest


    In reference to IFSTA,
    STBURNE you are about three quarters correct in saying that ifsta is a good reference book for fire streams. It is my opinion however that IFSTA needs to go back over there material(some of which is 40 years old)and revise if need be. With todays new equipment , required flows, Manpower situation,etc, I think you will agree that there needs to be progress.
    Why is it that IFSTA can only come up with a couple of pages on LDH?
    Talking about nozzle pressures for smooth bore tips. This is a good one. IFSTA states that a handline smooth bore nozzle NOZZLE pressure should be 50 psi. Any pressure higher than 50 will create a broken stream as well as a hard to handle dangerous handline. I personally know that nozzle handling techniques as well as specific nozzle combinations make that statement untrue but that is a whole different topic. I would like to share two nozzle reaction formulas obtained from IFSTA. The first formula is for determining the nozzle reaction for smooth bore tips and the second is for combination nozzles.

    smooth bore----1.57 x D squared x NP

    combo----------.0505 x Q x square root of NP

    Now check out the following statistics.

    1-1/8" tip @ 80 psi NP @ 336 gpm = 159 NR
    combo nozzle @ 100 psi NP @ 336 gpm =169 NR

    The IFSTA book says that the above mentioned smooth bore is dangerous because of the high nozzle pressure(80psi) but also say that a 100 psi combo nozzle at the same flow is OK when in fact it has a higher nozzle reaction making it even more dangerous. By the way the combo nozzle is in the straight stream mode. Heres two more.

    1-1/4" tip @ 80 psi NP @ 400 gpm = 196 NR
    combo nozzle @ 100 psi NP @ 400 gpm = 202 NR

    1" tip @ 80 psi NP @ 266 gpm = 126 NR
    combo nozzle @ 100 psi NP @ 266 gpm = 134 NR

    We need books like IFSTA and others to provide the fire service with valuable life saving imformation. I feel it is important to be continually updateing and research to find betters ways to do thing. God bless the dude that invented fire hose. Could you imagine where we would be if we still used buckets?

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