1. #1
    LT trk106
    Firehouse.com Guest

    Question What smooth bore tip size for 1 3/4" hose?

    We did some playing on the training feild today with our preconects. We run 200' of 1 3/4" hose with sm30 auto nozzles on the end for our attack lines. All preconects are plumbed with at least 2" pipe.
    My queston is this. We tried the 15/16' tip for our 1 3/4' lines at 170lbs. pump pres. at the panel. good stream reach and volume. We then tried the 1" and the 1.25" tips from our 21/2" playpipes on the 1 3/4" lines at the same pressure. WOW, what a stream. Great reach and incredible volume for a line that one ff. can handle in a pinch. Anyone out there ever use this setup on actual fire conditions? Good or bad?
    Thinking about trying one line with a smooth bore on it. But want to train with it first and see if its a viable working line. any comments would help muchly.
    Thanks. LT.

  2. #2
    S. Cook
    Firehouse.com Guest

    Post

    We've played with a similar setup in training and one firefighter could handle it no problem. The 1-3/4" set this way is a workable line, give it a try and see what happens. Let us know how you do.

    We use a similar setup on our 2.5" blitz attack line.

  3. #3
    DD
    Firehouse.com Guest

    Post

    Adjust your pump pressure until the nozzle pressure is at 50 p.s.i. (Measure it with a
    guage). The 15/16" solid bore will be flowing 185 g.p.m.

    Hey Paul, jump in on this one!

  4. #4
    LT trk106
    Firehouse.com Guest

    Question

    I'd like to put our pitot gauge on the 15/16" tip, but we dont have the coeficantto figure with that small a tip. If anyone has the numbers send them my way please.
    thanks for the input and keep it comming.

    LT.

  5. #5
    BIG PAULIE
    Firehouse.com Guest

    Post

    To LT trk106
    First a question on what you wrote.
    You talked about the tip sizes and engine pressures that you used. You also talked about the stream quality. However you didn't mention the flows or attack methods used for each ie interior or outside heavy stream attack. A lot of folks judge the effectivness of a fire stream based on how good or bad the stream looks. In my opinion appearance of a stream is not as important as how will the stream reaches the target and how much water is being deliverd. Interior streams as a rule do not require more than about 30' to reach the target. In this case a stream with a long reaching appearence will not be that important. The water volume will be more important as well as the stream type( straight or fog depending on the fire and method of attack).

    For an interior attack line I think you guys are on track with the 15/16" tip with a 50 psi nozzle pressure. The 180 gpm this tip delivers is pretty big amunition for most interior attack room and contents operations. In fact this is the handline of choice for many departments including FDNY.
    Now for the big flow exterior lines with smooth bore tips. here are some suggestions.

    1-3/4" 200' long

    1" @ 80 NP = 265 gpm
    1" @ 100 NP = 295 gpm
    1-1/8" @ 50 NP = 265 gpm
    1-1/8" @ 80 NP = 335 gpm
    1-1/4" @ 50 NP = 325 gpm
    1-1/4" @ 80 NP = 400 gpm

    2-1/2" or 3" 200' long

    1" @ 100 NP = 295 gpm
    1-1/8" @ 80NP = 335 gpm
    1-1/8" @ 100 NP = 374 gpm
    1-1/8" @ 115 NP = 400 gpm
    1-1/4" @ 80 NP = 400 gpm
    1-1/4" @ 100 NP = 460 gpm
    1-1/4" @ 115NP = 495 gpm
    1-3/8" @ 50 NP = 396 gpm
    1-3/8" @ 80 NP = 500 gpm
    1-1/2" @ 50 NP = 472 gpm
    1-1/2" @ 80 NP = 600 gpm
    1-3/4" @80 NP = 643 GPM


    All of the above mentioned figures come from the smooth bore discharge data sheet



  6. #6
    Sneezy_248
    Firehouse.com Guest

    Thumbs up

    Our dept. has had great sucess with smooth bores on 13/4 attack lines, good reach,plenty of flow. We are to the point of using smoothbores on everything but our 11/2
    lines.

  7. #7
    NUMBY
    Firehouse.com Guest

    Post

    We also use smoothbore nozzles. We go with the 15/16. It delivers 182 GPM. It is very easy for one person to handle. Since you only need 50 psi at the nozzle. we set the pump discharge at 125. There is roughly 50 lbs friction loss per 100' of 1 3/4 hose flowing 182 gpm. you might want to check your pump with a flow meter to make sure since plumbing will vary. The best way to determine if this setup will work for you is to go out and have some live burns, you will be amazed. Not only is it very easy to handle, but you can also get an effective semi-fog pattern that works great for hydraulic ventilation.

  8. #8
    FyrRokie
    Firehouse.com Guest

    Thumbs up

    OUR FIRE DEPARTMENT IS USING THE 1 &3/4 SMOOTH BORE AND THEY WORK GREAT IN FIRES. YOU CAN FIGHT THE FIRE AND NOT UPSET THE THERMAL LAYERING. IF YOU GO IN AND OPEN IT UP AT THE CEILING AND LET THE GIANT DROPS RAIN DOUWN AND SHUT IT DOWN. THEN ADVANCE THE HOSE. DO THIS UNTIL THE FIRE IS OUT


    ------------------
    FyrRokie

  9. #9
    LT trk106
    Firehouse.com Guest

    Cool

    THANKS FOR ALL THE RESPONSES.I'D LIKE TO LET YOU KNOW WHERE WE ARE RIGHT NOW.
    WE HAVE A FRONT BUMPER LINE ON OUR LEAD ENGINE THAT HAS A 100FT. OF 1 3/4" LINE.
    ON THIS LINE WE HAVE A SM-20 BREAK-APART AUTO NOZZLE. WEVE JUST ADDED A 15/16" SMOOTH BORE "SLUG" TIP BEHIND THE AUTO NOZZLE , AHEAD OF THE SHUT-OFF. WE HAVE DONE SOME TESTING ON THE DRILL FEILD AND FOUND WE CAN DELIVER OVER 303 GPM OUT OF THIS LINE IF THE NEED BE. MOST OF THE TIME WE WILL RUN THIS AT 80LBS. PANEL PRESSURE AND FLOW 178GPM.
    THE REASON WE STILL HAVE THE AUTO IS THAT NOT EVERYONE IS COMFORTABLE WITH THE SMOOTH BORE AS THEIR ONLY OPTION. YOU KNOW HOW THE FIRE SERVICE IS SLOW TO CHANGE THE THINGS THEIR COMFORTABLE WITH. THATS FINE WITH US SMOOTH BORE GUYS, CAUSE WE CAN STILL HAVE IT. ALL WE HAVE TO DO IS DO A QUICK UNSCREW OF THE AUTO NOZZLE AND WE ARE GOING SOLID STREAM.
    ONCE AGAIN THANKS FOR THE ADVICE AND WE WILL CONTINUE TO TRAIN AND IMPROVE OUR USE OF THE SMOOTH BORE NOZZLE.

    LT.

  10. #10
    STBURNE
    Firehouse.com Guest

    Post

    Lt trk106

    To answer your earlier question, according to the NFPA Handbook, the coefficient for handheld smoothbore nozzles is 0.96-0.98.
    A common misconception is that the formula 29.7 * d squared * square root of NP = GPM is accurate for all smooth bore nozzles. This is only the case for deluge or monitor nozzles that have a coefficient of 0.997.

    For hand held smooth bores:
    28.9 * d squared * square root of NP = GPM
    is more accurate.

    Many flow meters are incorrectly calibrated due to this misunderstanding.

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