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  1. #1
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    Default Automatic vs Smooth Bore for Aerial Master Streams

    Does anyone have thoughts on using an automatic nozzle versus
    stacked tips for an aerial master stream.


  2. #2
    Truckie SPFDRum's Avatar
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    LFDTruck2: For your first post, you picked a good one. The debate of smooth bore vs. auto-tip has consumed many of pages here on the forums.
    Both are excellent choices; all depending on the situation.
    There are guys on here that can give you some extremely in-depth information on the pros and cons of both. Me, I'm just a Rum in the back, so I try to keep it simple!

    If you have a well involved, well vented building -roof in, floors in, collapse- a smooth bore tip will get you an amazing amount of water on a spot in a hurry. It's also good for hydraulic overhaul as it has very good reach. Salvage would be a minor goal by this time. I know guys that swear by smooth bore for car fires, I have yet to have opportunity to try it.
    With an auto-tip, you get the advantage of the conversion factor of water. You can darken down a large area quickly, maybe with less water damage if salvage is a possibility. Again, if it's well vented, and all the steam goes out with the smoke, not much advantage. Does make good news footage though!
    Just my thoughts...hope it helps.
    Last edited by SPFDRum; 03-06-2002 at 04:59 PM.
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  3. #3
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    I'd go with the smoothbore. I have seen fog streams break up and not hit the seat of a fire because of the heat of a well involved building. The SB also has more punch for hydraulic overhaul.
    Last edited by ADSNWFLD; 03-09-2002 at 08:37 AM.

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    Thumbs up

    In my city our Tower truck is equipped with both an automatic and smooth bore nozzle. The smooth bore nozzle is known as "the fire killer". Most times when the tower goes up the building is on its way down, thus there will be little to no salvage.
    The smooth bore throws a tremendous log of water that will penetrate and hit the seat of the fire. The automatic stream will ually convert to steam before it gets to the seat of the fire. This steam conversion will not do any good since the building is usually well ventilated(possibly no roof at all).
    I feel that both nozzles have a good purpose, however it is up to the operator to select which nozzle would be the most efficient for the given situation.
    Take Care & Be Safe

  5. #5
    Forum Member Bones42's Avatar
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    Automatic vs Smooth Bore is a big arguement for hand lines.

    For Aerial devices and Master streams, there is no choice. Smooth Bore. Why would you ever want a 1000gpm fog other than to cool people off on a hot day?

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    Truckie SPFDRum's Avatar
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    Arrow

    Bones: I wish it was that cut and dried. Take a large wharehouse with tip-up wall construction and spancrete roof, you would have to get a lot of water to the seat of the fire (if you can reach it) to get it to darken down. Where as a fog nozzle will give you almost instant conversion.
    We had a single story wood specialties building of that construction (20' vertical walls). We put the sticks straight out into loading dock doors, and got a good knock-down because of the conversion. With very little threat of collapse, we where able to mop up with hand lines.
    And so the debate goes on!!!
    My posts reflect my views and opinions, not the organization I work for or my IAFF local. Some of which they may not agree. I.A.C.O.J. member
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    If you are going to master streams then you have already written off the building. I have seen both use and the smoothbore is most effective to use for a few reasons. Better reach, better penetration,
    more GPM, more integrity of the stream because it is solid intead of broken up little droplets that can be easily taken by even a slight breeze. It is up to the officer in charge. Whatever he decides is the way it goes but that doesn't mean you can't help influence his decision.

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    I haven't seen anyone mention the use of deck guns for exposure protection. I would think that this is an application where you are not looking for penetration. You only want to wet down the shingles and windows, not rip them up. Seems like a fog nozzle wuold be the ticket?

    Anyone have any experience with this use that you can pass on?
    Lead by example...
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  9. #9
    Forum Member Bones42's Avatar
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    We used a portable gun once for exposure between two buildings. Worked very well. The width between the buildings was about 10' down to 3' and the length was about 70'. The gun had a straight tip and was shot straight down the side of the building for over an hour. Of course, the two buildings were less than 20' in height. Happened during a snow storm with strong winds blowing in off the ocean. A fog would never have reached. But, I can see your point where it could be used, and that is why we keep an adjustable tip on our truck for when it's needed. We leave the straight tips on and replace them with the fog when necessary.

  10. #10
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    Pretty amazing reading the nozzle debates. The Automatic will flow just as much as any smoothbore and in most cases a lot more. Do you supose our 500 to 2000 gpm and 750 to 4000 gpm automatics won't out flow the 1 1/4" to 2" stack tips?? More water huh??? Why wouldn't a tip at 100 psi it has to reach further than a smooth bore at 80 psi? Why wouldn't a stream at 100 psi not penetrate further than one at 80 psi? The laws of physcis don't change with water. The impact is higher, always. If you doubt that hold your smooth bore straight up next to a fog nozzle. The higher np always wins, same when it is level or any angle in between. All the manufacturer literature supports better reach with a fog tip. The SB penetration and reach story is just that an old wives tale, not based upon any fact. You can't support it on the drill ground either. Water is water the fire doesn't care.

    Using a deck gun for knock down doesn't mean the building is written off. Where pray tell is that a law? All the measurements for stream reach are based a measure of 90% f the water going through a given size hole. So water hitting is the same at the end.

    Why would you ever want to use an automatic on a master stream versuss a SB? Gee that is easy! You can only oump 500 gpm tank to oump on most NFPA compliant pumpers, so you going to store a 1 1/4 or 1 3/4" tip on the rig? You hook to a hydrant and the supply line length varies, so what tip you gonna use? It will vary with supply, the automatic is always the right size and can grow from tank to supply changeover or shrink as the water supply shrinks.

    Anyone got any proff that a 1000 gpm stream from an automatic nozzle will vaporize and a smooth bore won't? There is thermal imager proof it doesn't occur, so where are your sources? More punch? An 80 psi stream has more than a 100 psi stream? How do you figure?

  11. #11
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    Default Physics?

    I am neither a proponent of solid stream or fog nozzles. It's kind of like being a mechanic. They have many different tools in their toolbox, many of which are the same size...1/2" box wrench, open end wrench, six piont socket, twelve point, adjustable wrench, etc. They all do the same job, just slightly differently. Sometimes only one of them is the right tool for a certain job. That is the one to use at that time, but it sure is nice to have the other choices for a different job. Put the egos away and admit that sometimes there is more than one way to skin a cat.

    As for physics, that is a different story. Correct as stated, "the laws of physics don't change with water." Indulge me a little here. Items of equal weight (mass) travel or fall at the same rate, regardless of the material. If I drop an eight pound squash and an eight pound watermelon from the same height, they will hit the ground at the same time. But if I drop an eight pound cannon ball and eight pounds of feathers from the same height...the cannon ball will hit the ground much more quickly. That is because of the physical shape of the feathers. They have a great deal of surface area and therefore offer a great deal more wind resistance.

    A solid stream is like the cannon ball, and the fog stream is like the feathers, broken up into many small parts offering much more wind resistance. Back to my experiment with the cannon ball and the feathers...which do you think will have greater penetration. Obviously the cannon ball. That's why they didn't shoot feathers out of cannons.

    On the other hand, the cannon ball will create one deep hole at point of impact, but if I want to cover a lot of area with less punch, the feathers are the thing to use. Like using a fog nozzle for exposure protection to cover a lot of area without damaging it.

    By the way, the laws of physics don't change with water, but they do change with the shape of it! Again, I don't say one is better than the other, just that they are different. If one nozzle, one tool, one piece of apparatus was perfect for everything, there would probably only be one type of everything available. Why make anything else?
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  12. #12
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    Oh I see the stream from the smooth bore doesn't break up because it can violate the laws of nature. You could not tell at the enf\d of a stream if it is from a smooth bore or fog. All the forces of nature are working on both, thus the 9/10 rule.

  13. #13
    Senior Member Dalmatian90's Avatar
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    A solid stream is like the cannon ball, and the fog stream is like the feathers, broken up into many small parts offering much more wind resistance.

    Bad analogy.

    A better one would be, oh, slugs and buckshot from a shotgun. The buckshot will probably have more wind resistance; the slug might go just a bit further and stays together a bit better. I wouldn't want to be at the receiving end of either since they'll both be effective in killing me. Sometimes, you prefer buckshot, sometimes slugs, but they both get the deer.

    If you are going to master streams then you have already written off the building.

    That's just plain unfortunate. Many times you'll save more of the building and more importantly it's contents going to the big streams for a minute than little streams for an hour.

    For Aerial devices and Master streams, there is no choice. Smooth Bore. Why would you ever want a 1000gpm fog other than to cool people off on a hot day?

    Thinking back to the last fire I was at where an aerial master stream was in use, a solid bore would have gone in one end and out the other with no appreciable effect on the fire.

    It wasn't our aerial -- our '76 at the time couldn't do such a manuever. Building had 1/3 fully involved on arrival, 1/3 heavily involved, and 1/3 still in good shape. With one tower and several medium flow handlines operating on the fully involved section to knock down the heat source, the 2.5" crew in the attic was still losing. They withdrew, an aerial ladder dropped down perpindicular to the end of the attic, and opened up a fog into the attic. Blew the fire out and into the already burned area. A solid bore would've gone in one end, out the other, and been really an ineffective waste of water.

    Yeah, building was a loss due to heavy involvement prior to 911 even being called. We did save the business records though of the tenant in the part of the building we could defend.

    Modern aerials, towers, telesquirts open up many possibilities we didn't have before for tactical use of heavy streams. Being able to drop down at any angle, at full extension, and operate nozzles flowing 1000gpm or more perpindicular to the stick, with remote control of the nozzle, gives us the ability to get up close and personal with substantial flows to simply knock the living stuffing out of a fire. Can't do it all the time for a plethora of reasons from access to collapse zones, but when you can aggressive aerial master streams eat fire.

    Not having remote control nozzles, not being able to adjust for different flows without changing tips, not being able to vary pattern for penetration (straight) or pushing (fog) all limit the ability to act aggresively.

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