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Smooth bore Nozzles

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  • Smooth bore Nozzles

    Has anyone had any trouble with fellow officers accepting the use of smooth bore nozzles. I am having an acceptance nightmare. I understand old habits die hard but.....

  • #2
    They still prefer technology that meets most areas needs better, eh?

    Why can I see Smokeetr's comment so fitting in with the early 60s if you substitute in "fog" in place of smooth bore...

    Comment


    • #3
      I would have to say in my defense, unlike the 60's where they were trying to introduce this new "fog" concept, Smooth bore nozzles have already proven themselves as the weapon of choice in interior firefighting. Removing the stigma that there is no other way can be challenging at best.

      Comment


      • #4
        Smokeetr, some of our officers haven't quite swallowed the snooth bore pill yet but they're getting there.
        To keep everyone happy, we purchased some combination nozzles with the screw off fog head that turns the nozzle into a 15/16-inch smooth bore. Everyone pretty much seems to be comfortable with them. Actually the hardest part was tying to get our chauffeurs familiar with pumping at a lower pressure and making sure the hose being used has the correct pressure whether fog or smooth bore nozzle.
        Give it time, do a little more drilling with them alongside fog nozzles and get them comfortable with them.

        Lt. Kevin C. (aka Pokey)

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        • #5
          For an excellent reference on smoothbore nozzles vs. combination nozzles, check out a Fire Engineering video put together by Dave Fornell, a retired captain from Danbury, CT. He has done a lot of testing and teaching with smoothbores and fire streams. I can't recall the video's title off the top of my head, but it's put together well and presents some good info. in a just the facts manner.

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          • #6
            Actually, fog was well proven by the early sixties after it's introduction decades earlier.

            They may be the weapon of choice in a *particular* method of interior firefighting, but there is more than one set of tactics that are effective in interior firefighting.

            When looking to move back to smoothbores, or to combination fog nozzles, you have to evaluate how you fight fire and how the nozzles fit into the picture.

            The departments that "led the charge" back to smoothbore nozzles have very specific reasons and circumstances -- take a look at NYC where very large building size, adequate staffing early in an incident, high potential of arriving while there is viable life in the immediate vicinity of fire, and aggressive search & ventilation tactics among other factors make smoothbores for standard fire attacks practical.

            You can make very effective fog attacks. And keeping the rest of your tactics the same but substituting suddenly straight streams or smoothbores are going to mean things don't work the same.

            Similiarly, you can make very effective smoothbore or straight stream attacks, but if you suddenly introduce a narrow or wide fog pattern without changing the other tactics you used with the smoothbore, things don't work the same.

            If you're going to have acceptance of any nozzle, it has to be introduced as part of a set of tactics, and the circumstances those tactics are used. Using the wrong stream pattern with the wrong set of tactics (not only hose, but also search and ventilation tactics) is a recipe for failure.

            For most communities, given their staffing, density, and hazards, combination fog nozzles simply offer the most flexibility to go from straight-stream attack when staffing and needs allow, to attack fog or indirect fog when conditions dictate. And that's what you have to look at very specifically and demonstrate to the "old timers" why it would be best for your community to return to smoothbores.

            Comment


            • #7
              There is some excellent information on the application of the smoothbore and the fog nozzle in the book

              "Firefighting Principles and Practices" by William Clark.

              The whole book is great...however Chapter 2 has the most relevance to this discussion.
              It Covers Fog: Theory and Practice, Steam Extinguishment, Disadvantages of Fog, Solid and Straight and Solid Streams.

              It also mentions some tests conducted in which the solid bore was superior to the fog in knockdown and extinguishment. While using less water and taking less time for extinguishment than the fog.

              I hope that helps.

              Two cents from a fireman.

              Comment


              • #8
                We use fogs for our interior attacking....i personally prefer them. I have also used SB when i worked in Illinois and i did like them, for several reasons.

                Yes you do lose alot of penetration with a fog, but for hydraulic ventilation...you cant beat it..Also fighting car fires with a fog is so much easier...well for me it was:-)

                ------------------
                Engine / Squad Co.# 7

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                • #9
                  My department switched to smooth bore nozzles several years ago. We use a 7/8" tip on our 1 3/4" attack lines and a 1 1/4" tip on our 2 1/2" attack lines. Both tip's have had great success with knocking down large volumes of fire. There is a good article in the March 2001 Fire Engineering on nozzles types and uses. I think some of the reasons to go with a smooth bore is the increased flow, lower nozzle pressure, but most important the lower nozzle reaction. If a firefighter can't control the nozzle the first thing that usually happens is the nozzleman gates down the shutoff. This cuts back on the pressure, flow and quality of the stream. All i can say is get out and train with both types of nozzles. Use flow meters and pilot gauges to actually see what the nozzles you are using are flowing. If you want high flow and and your personnel to safely handle the line smooth bores offer the best choice. Just my two cents.

                  Stay Safe

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                  • #10
                    Like Jim said, you gotta get out there and train and practice and see what works best for you.

                    On paper, automatic combination nozzles can be very competetive with smoothbores depending on what your doing and how you operate.

                    Let's look at nozzles first:

                    7/8th tip @ 50psi nozzle pressure = 161gpm and 60lbs of reaction.
                    An automatic tip @ 100psi nozzle pressure delivering 161gpm has 81lbs of reaction.

                    As flows increase, the nozzles come closer in reaction.
                    A 7/8th tip @ 75psi = 197gpm and 90lbs of reaction.
                    A automatic tip @ 100psi nozzle pressure delivering 197gpm has 99lbs of reaction.

                    Everything else the same, you only need to increase your pump pressure by the difference in the needs of a nozzle -- to flow 161gpm, you need 50 more psi to feed the 100psi automatic. To flow 197gpm, you need 25 more psi to feed the 100psi automatic.

                    The "standard" friction loss for 1.75" rubber lined hose gives a FL of 40psi/100' @ 161gpm and 60psi/100' @ 197gpm.

                    However, many newer designs of firehose are much more efficient. Angus Red Chief and Hi Combat are given FL by the manufacturer of 25psi/100' @ 161gpm and 37psi/100' @ 197gpm.

                    So let's look at a setup involving two variables:
                    1) 7/8ths smoothbore v. Automatic combination fog on straight stream
                    2) Traditional rubber lined 1.75" hose v. Newer design lined 1.75" hose. I choose 200' to use in the scenarios -- a common preconnect length these days.

                    1) 7/8ths @ 161gpm, Conventional hose
                    Reaction: 60lbs
                    Nozzle Pressure: 50psi
                    Friction Loss: 2 x 40 = 80psi
                    Pump Discharge Pressure:130psi

                    2) 7/8ths @ 161gpm, Modern hose
                    Reaction: 60lbs
                    Nozzle Pressure: 50psi
                    Friction Loss: 2 x 25 = 50psi
                    Pump Discharge Pressure:100psi

                    3) Automatic @ 161gpm, Conventional hose
                    Reaction: 81lbs
                    Nozzle Pressure: 100psi
                    Friction Loss: 2 x 40 = 80psi
                    Pump Discharge Pressure:180psi

                    4) Automatic @ 161gpm, Modern hose
                    Reaction: 81lbs
                    Nozzle Pressure: 100psi
                    Friction Loss: 2 x 25 = 50psi
                    Pump Discharge Pressure:150psi

                    5) 7/8ths @ 197gpm, Conventional hose
                    Reaction: 90lbs
                    Nozzle Pressure: 75psi
                    Friction Loss: 2 x 60 = 120psi
                    Pump Discharge Pressure:195psi

                    6) 7/8ths @ 197gpm, Modern hose
                    Reaction: 90lbs
                    Nozzle Pressure: 75psi
                    Friction Loss: 2 x 37 = 74psi
                    Pump Discharge Pressure:149psi

                    7) Automatic @ 197gpm, Conventional hose
                    Reaction: 99lbs
                    Nozzle Pressure: 100psi
                    Friction Loss: 2 x 60 = 120psi
                    Pump Discharge Pressure:220psi

                    8) Automatic @ 197gpm, Modern hose
                    Reaction: 99lbs
                    Nozzle Pressure: 100psi
                    Friction Loss: 2 x 37 = 74psi
                    Pump Discharge Pressure:174psi

                    Which brings up the paradox of using a 100psi automatic combination nozzle at 197gpm with modern hose needs 20psi LESS at the pump, than a 7/8ths tip fed by 20 year old hose. (Of course, that 7/8ths needs 50psi less if it has the good hose, too!)

                    If you mainly work off of your truck's preconnects, and you put together a "system" of good hose and nozzles, you could very well have a situation where a high flow automatic costs you 9 extra lbs of reaction, with 20psi less pump discharge pressure than a smoothbore at the same flow! It's all how you mix and match to meet your needs.

                    The extra 50psi on medium flows and 25psi on moderately large flows could be a detriment if you work from standpipes often -- where you may run into a limit of the PSI they can be pumped at. And smoothbores have the advantage in poorly maintained standpipes of passing the garbage and rust and what not through. But while many larger cities encounter and work from standpipes routinely, I'd venture to say the majority of departments in the nation work off preconnects in buildings three stories or less most of the time. I'd also venture to say most of the rooms you're fighting fire in are less than 50' long, probably less than 30' even for a residential hall so the extra reach of a smoothbore becomes irrelevant.

                    Not to say even if most of your fires are in single/double/triple occupancy residences that smoothbores don't have a role in your department -- they might be the cat's meow for an interior stand from a relatively "safe" position against a fire in a commercial building where your going for reach and quick knock down.

                    The combination automatics simply give you more flexibility, going from smooth-bore like performance on straight stream, to allowing narrow "attack fog" when limited staffing or limited water means you need to make the most of every drop -- and the simple physics is a fog nozzle in the average home will absorb more heat many times faster than a smoothbore of equivelant flow can, and use much less water to absorb that heat.

                    Matt

                    [This message has been edited by Dalmatian90 (edited 04-27-2001).]

                    Comment


                    • #11
                      //you could very well have a situation where a high flow automatic costs you 9 extra lbs of reaction, with 20 psi less pump discharge pressure than a smoothbore at the same flow!

                      Or, you could compare apples with apples and use a low pressure automatic nozzle and have the same flow and same reaction plus the flexibility of a combination nozzle. This is 2001 not 1970 where 50 versus 100 psi are the only options.

                      //I'd also venture to say most of the rooms you're fighting fire in are less than 50' long, probably less than 30' even for a residential hall so the extra reach of a smoothbore becomes irrelevant.

                      Who says a smoothbore at equal flow and lower EP can out reach a combination nozzle at 100 psi?

                      //The combination automatics simply give you more flexibility, going from smooth-bore like performance on straight stream, to allowing narrow "attack fog" when limited staffing or limited water means you need to make the most of every drop -- and the simple physics is a fog nozzle in the average home will absorb more heat many times faster than a smoothbore of equivelant flow can, and use much less water to absorb that heat.

                      Amen!

                      Comment


                      • #12
                        Can you say it any better. Good post Larry.

                        Comment

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