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  • stacked tip question

    This is a two-part question:

    For a ladder pipe with a stacked tip, what tip size would be best?

    For a duce n' a half, same question.

    What I am looking for is volumes and pressures for different size tips and what would be best. The reason for this is I see companies leaving the smallest tips on each and I know the flow and stream are not best for maximum penetration and volume. I would like to convince some people that taking off a few tips would give the best penetration and volume.




    ------------------
    Keep Safe!

  • #2
    Jizumper-5: You are on the right track. If you have a water supply that will handle big flows here is the data. Please keep in mind that NFPA recommends a nozzle pressure of 50-psi on a hand line and 80-psi on a master stream. If you over pressurize any SB nozzle you will start breaking up the stream and you will not have the reach you need to get the water on the fire. You will still have the flow but not the type of stream needed. Just remember the two most important factors in extinguishing a fire.
    1. Rate of application
    2. Type of stream applied
    The technical data for a master stream: All flows reflect 80-psi NP.
    1 3/8”= 502gpm
    1 ½”=598gpm
    1 ¾”=814gpm
    2”=1029gpm

    And for 2 ½” at 50-psi NP.
    7/8”= 161gpm
    15/16”=185gpm
    1”=210gpm
    1 1/8”=266gpm
    1 ¼”=328gpm

    If you have ample water supply and the fire is calling for big water then take a tip or two off. Hope this helps.

    Comment


    • #3
      fire827, I repectively disagree with you on your nozzle pressures. Steams do not break up they get better.


      Handlines
      1" tip [email protected] 100 psi np 300 gpm

      1-1/4" @ 80psi np 400 gpm

      masterstreams
      1" @ 200 np
      1-1/8" @ 200np
      1-1/4" @ 115 np
      1-3/8,1-1/2,1-3/4", and 2" @ 120 to 175 psi

      These stream produce hard hitting far reaching streams

      Comment


      • #4
        Paul:
        /Steams do not break up they get better.//

        I would have to qualify this: They get better proivded you are using a stream straightener behind them. Without this most of them do break up at the higher pressures.

        I have also found that certain ball valve shutoffs destroy the stream because of the ball design. (Back of ball is cut out creating lots of turbulance.) The more pressure you cram to it the worse the stream gets. This is a problem of the shutoff design not the smooth bore.

        Another factor will be the length of the SB. I prefer to have smooth bores that are no less than 6 inches in length. This provides a more stable flow than the stubby tips commonly found on a break away nozzle.

        Just my two cents worth.


        ------------------
        Kirk Allen
        First Strike Technologies, Inc

        Comment


        • #5
          Please keep in mind that NFPA recommends a nozzle pressure of 50-psi on a hand line and 80-psi on a master stream. If you over pressurize any SB nozzle you will start breaking up the stream and you will not have the reach you need to get the water on the fire.

          This has always puzzled me from the NFPA standpoint...

          What's the difference in stream quality from a 1.25" tip if it comes from a gun at 80psi or a handline at 80psi?

          So why does NFPA only go 50psi for handlines?

          Because of some myth that it's too hard to handle?

          Comment


          • #6
            I'm with KEA also, I've had experiences where flowing at higher pressures have made the stream break up as well as increase the nozzle reaction. I've always flowed my
            2 1/2's w/ smooth bore at the 80 psi range, w/ a 1" tip. My 1 3/4" I normally flow with a NP @50 psi, and this is normally with a 15/16" tip. Also none of our 2 1/2" smooth bore nozzles are the "stubby's" and I've never used one. Our 1 3/4 are of the shorter length smooth bores. I'm really glad this was posted, I can't recall ever flowing over 80 psi NP, but in my next shift training I think I will just to see if there is any difference in the streams.

            =========================================
            The above is my opinion only and doesn't reflect that of any dept/agency I work for, deal with, or am a member of.

            Comment


            • #7
              What youn's really need is a fourteen yearold runnin that pump!! Whoeeee lookee that water fly!

              Comment


              • #8
                OK, I tried this once, got a call and it got left in cyberspace, so here it is again. Most ladder pipes on straight ladders start at 1-3/8(500gpm) because they are sensitive to too much reaction force. If you have a platform you can usually flow much more water depending on the mfg specs. Still it does matter HOW you achieve your gpms. For instance you can get 1990gpm from a 2-1/4 nozzle at 175psi, but the reaction force is 1391lbs. If you go to a 2-3/4 tip you still get 2010gpm but at 950r/[email protected] a much better way to go. Really it all boils down to reaction force. You have 3 variables, gpm, reaction force, and nozzle pressure. each one effects the other. What you need to decide is how much reaction force you can handle(2firefighters is about 150r/f, 1 firefighter is about 65r/f)once that is done you need to find the max amount of gpm you can flow at that r/f. On a 2-1/2 it's about [email protected]/p and 123lb r/f(1-1/4tip). 2 firefighters can still move that line. With one firefighter on a 1-3/4 it's about [email protected]/p and60lb r/f(7/8tip), 1 firefighter can maneuver that at a crouch position. If you compared that reaction force to a fog, you would find that your gpm would be cut to 224gpm and 112gpm respectively. This why smooth bores are becoming more popular, more gpm, less reaction force. But I'll admit that there will always be a place for fogs(generally non occupied spaces). So that is a rather long winded justification for establishing your reaction force requirements first, then work from there. KEA is correct in his assesment of bales, another call!!! Back again, anyway KEA is right, the cutout bale will kill the stream. If you take a long tip like he describes, with a non cutout bale it will outperform a brand x cutout bale even with a stream straightener. Watch out for bale bore size, if you have a choice specify a 1-3/8 bale (this is a normal 2-1/2 size bale) for both the 1-3/4 and 2-1/2 nozzles. The stub tip is also not a good way to go, but it works OK for what it is expected to do. Sorry to take up so much space, it's not an easy topic.




                [This message has been edited by BLACKSHEEP-1 (edited 06-14-2001).]

                Comment


                • #9
                  Thanks for everyones 2 cents. This is exactly what I am looking for!

                  ------------------
                  Keep Safe!

                  Comment


                  • #10
                    Fire827 and others, can you cite the reference material you got your information from? I work with the facts and need citations to prove my point. Some people think opinions hold more ground than fact....Thanks!

                    ------------------
                    Keep Safe!

                    Comment


                    • #11
                      Look in an IFSTA Fire Streams book, a pump or nozzle manufacturers flow/friction loss calculator or any of the nozzle manufacturers websites!.. If you want to prove your points, do the homework! Both questions are completely dependent on your own operations.. what is your ladder pipe rated for? 600 gpm? forget the big tips. Do you want to drag the 2 1/2 all around a building or sit on it on the front lawn? Again, could be difference between 1 1/8 and 1 1/2

                      Comment


                      • #12
                        I would like to convince some people that taking off a few tips would give the best penetration and volume.

                        Not only that, but it ensures a few tips get taken off!

                        How many times have you seen the picture or video (or first hand) of the fire that needs 1,000gpm being fought with the 500gpm tip? (yeah, yeah, yeah for the picture the moment in time thing notwithstanding)

                        I work with the facts and need citations to prove my point.

                        Citations will never prove the point to some folks. The best way I've found is to get out the rig and make them show you their way is better. That works two-fold. If their way is better, you see it first hand and you can adjust your position accordingly. If your way is better, they see it first hand.

                        Seeing is believing but then again some will ask "who you gonna believe, me or your lyin' eyes?"

                        For the ladder, stay in the mfg limits and run the tests. Call the mfg and ask what the limits are in different configurations.

                        Or, your compadres can simply figure it out for themselves if you're tactful enough. For the sake of arguement let's use a 1.375", 1.5", 1.75" and 2" stack.

                        If all flow pressures are equal (80psi):

                        - 1.375" - flows 502gpm which weighs 4,183# per minute or 70# per second
                        - 1.5" - flows 597gpm which weighs 4,973# per minute or 83# per second
                        - 1.75" - flows 815gpm which weighs 6,789# per minute or 113# per second
                        - 2" - flows 1,062gpm which weighs 8,846# per minute or 147# per second

                        Just set this up on the white board using your stack tip sizes and let them do the math. The formula is 29.7 X nozzle dia squared X sq. rt. of the NP.

                        Build the chart and ask the questions:

                        Which one flows more water (volume)?

                        Which one has more impact (penetration)?

                        Now, all streams have the same velocity (108fps), but which one hits harder?

                        And then there's always "who's gonna be the one to climb up there and change the tip in the middle of a firefight?"

                        For the 2.5" drag 50' off the truck and try it out.

                        Elkhart makes a 2.5" ID ball shut-off too.

                        Some people think opinions hold more ground than fact.

                        And we're loaded with them in the fire service. Read just about any topic in these forums and you'll see that.

                        But I'll admit that there will always be a place for fogs(generally non occupied spaces).

                        BLACKSHEEP-1, you're not biased are you?

                        No fogs in occupied spaces?

                        Why?

                        Comment


                        • #13
                          Because I prefer my victim's skin still attached.

                          Comment


                          • #14
                            Blacksheep: Excellent answer - I couldn't have said it better.
                            Asst Chief Jim Kron

                            Comment


                            • #15
                              BLACKSHEEP-1

                              Because I prefer my victim's skin still attached.

                              By no means have I seen anywhere near everything, but in 20 years I have yet to see skin falling off a victim because of a nozzle.

                              Perhaps you could cite cases or give references to a properly operated auto or fog causing this?

                              D.C. Kron

                              I couldn't have said it better.

                              Come on D.C., you've got to have a little more creativity than that.

                              How about "Because I prefer my skin still attached?"

                              Or

                              "Because I prefer my firefighters skin still attached?"

                              Or

                              "Because you'll steam your victims to death" (as if a little steam burn would be the worst thing that could happen to them when they're trapped in their burning whatever).

                              There's a ton of other nozzle myths out there. How about this one:

                              "A solid stream or fog nozzle stream set at less than 30 degree fog (there's that number agian Blacksheep) will conduct electricity. So we don't use solid streams or less than 30 degree fogs it in case we forget to turn off the power."

                              Or, "1.5" fog nozzles should only be flowed at 150gpm maximum, that's why we use solid streams, we can flow 185gpm."

                              [ 07-15-2001: Message edited by: mongofire_99 ]
                              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!

                              Comment

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