1. #1
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    Default CAFS and hose line size - how does it change?

    First, I'm a rookie volunteer in a CAFS based department and still trying to soak everything up. Been through the basic and mandatory and looking to do FF1/FF2 this spring.

    As I've lurked, I've seen lots of threads talking about where you use 1.5", 1.75" and 2.5" hose and began wondering how the use of CAFS affects this. To date, I've been to a couple fires and we've used only 1.75" line and in some cases before the 2nd line was laid, the fire was out. Mind you, where we are at, its mostly SFD and farms.

    With that, does it change your opinion of needing a 2.5" line if its a CAFS line?

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    You still should pull a line that is large enough to do the job if for any reason that the system fails.
    Also a 21/2" CAF's line eats fire, it has knock down power that is more along the lines of a master stream, and can be used to Blitz well involved buildings, and its light enough to be moved around once it is charged.

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    Captaincvfd is right you need to size your line to the fire. Remember CAFS works not by decreasing the required flow needed, its works by increasing the waters effectiveness. It still boils down to GPM vs BTU no matter if its CAF or plain water flowing through the nozzle.

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    CAFS does not require the same water flow. The chemicals added to the water do change the waters characteristics, but that’s not what causes the reduced flow required to extinguish the really hot fires. There have been many tests that prove CAFS uses MUCH less water in the foam to extinguish and absorb MUCH more heat.

    One of the many reasons for this is the CAFS foam is 90% efficient, and water streams are only 10% efficient. You can see this by observing the amount of water that runs out the door and into the street with water applications and there is very little if any water wasted when using CAFS.

    CAFS flow should be measured in what’s coming out of the hose instead of measuring how much water that it took to make the foam. If you scoop up a handful of the CAFS foam you will be holding a product that is 99 and a half percent water. A full flow CAFS in a 1-1/2 will discharge 985 gpm with 50 gallons of water and 125 cfm of air.

    A 2-1/2 is almost always overkill except for the largest of the industrial fires.
    Mark Cummins

  5. #5
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    Quote Originally Posted by cfire3 View Post
    CAFS does not require the same water flow.

    One of the many reasons for this is the CAFS foam is 90% efficient, and water streams are only 10% efficient.
    Firefighting water streams are much closer to 50-75% efficient, depending on the application method used. To be safe, you should match the needed water flow-rate with the involved fire load. If the CAFS deals with the fire more effectively and quicker than plain water, thats great.

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    Sorry to burst your guys' bubble (pun intended), but CAFS is a poor choice for a myriad of reasons. Unless your dept. does only exterior attacks on vacant or non-tenable fires, then I suggest you get rid of it before someone dies or is seriously injured. cfire3, there is no way your getting a flow, real or simulated, of 985 GPM out of an 1.5" CAFS line. That might be the calc. some propeller-head gave you, but the fact is your not flowing that. And because your not flowing that, your not reaching your critical flow, which is what is required for fire suppression. If you are flowing a reduced GPM, then it is impossible to be attacking the heat side of the fire triangle and making progress. You are displacing O2, not reducing the heat, just like an indirect or fog attack. The flame itself might go out quick, but the heat is definitely still there. And I don't want to speak for anyone else, but having a hoseline charged with so much pressure that you slide backwards from the nozzle reaction doesn't sound safe to me, especially in areas of reduced staffing. If your going inside, take a high volume, low pressure hoseline and nozzle combination that will put fire out the quickest BY REDUCING THE HEAT and not pushing fire through voids and into what WERE tenable spaces before the fire dept showed up. Visit the NIST website and get on board with the rest of the fire service that isn't even measuring fires in BTU's anymore, but megawatts of energy being released, because of the exponentially increased fire loading of today. And if a 2.5" is overkill for any fire that isn't industrial, than I guess we've all been doing it wrong for the last 350 years. Or maybe you've never been more than 2 stories above the ground in an IDLH fire environment.
    NorCal Firefighter

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    I'm glad you mentioned the NIST site because they have published a lot of great information about the advantages of CAFS over water. Water is preciouse, but it can be greatly improved with CAFS, and CAFS absorbs way more heat than non-CAFS applicatins. example"
    "The flow rate was 20 gpm of water or solution. At the 4-foot-high level, where "Heat…would directly affect the stress/survivability of trapped occupants...and also that of firefighting personnel involved in rescue/suppression operations" (Colletti, 1993b, p. 42), CAFS was found to be 480 percent more effective than plain water in lowering the temperature. "

    And I can asily flow 1,300 gpm CAFS foam through 1-1/2 because it's compressed. Convert 185 cfm into gpm by multiplying 7.48, it all goes through the hose to give a very high application rate. It helps to quit thinking that foam works like water, it doesn't. It's much better, when it's used right.
    Mark Cummins

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    One advantage with CAF is that the normal water friction loss equations go out the door. There is some loss as the mixture "scrubs up" in the first length but after that it can be ignored.

    I have seen a 1,000 meter CAF line pumping away at full noise.

    Would we use our CAF inside a decent structure? Not on your life, we do not like the idea of steam cooking ourselves. We will attack from exterior with CAF if it will not extend the fire, or we will use a solution mix (no Air) inside for penetration.

    Gives a better knockdown.

    Great for scrub / bush and car fires, or any fire outside.

    Just observations from someone who has done CAF and non-CAF attacks and seen the differences.
    Psychiatrists state 1 in 4 people has a mental illness.
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    [QUOTE=FlyingKiwi;926011]I have seen a 1,000 meter CAF line pumping away at full noise.

    Would we use our CAF inside a decent structure? Not on your life, we do not like the idea of steam cooking ourselves. We will attack from exterior with CAF if it will not extend the fire, or we will use a solution mix (no Air) inside for penetration.

    Just curious when you 've steamed yourself with cafs was it smooth bore or Fog nozzle, Because the only time i have seen it as an issue was when we had no ventilation high heat and used a narrow cone fog pattern, and we inverted the atmosphere instantly, other then that we have had good luck with it otherwise.
    Our policy is if its burning we use the Cafs.

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    Quote Originally Posted by dbier57 View Post
    Sorry to burst your guys' bubble (pun intended), but CAFS is a poor choice for a myriad of reasons. Unless your dept. does only exterior attacks on vacant or non-tenable fires, then I suggest you get rid of it before someone dies or is seriously injured. cfire3, there is no way your getting a flow, real or simulated, of 985 GPM out of an 1.5" CAFS line. That might be the calc. some propeller-head gave you, but the fact is your not flowing that. And because your not flowing that, your not reaching your critical flow, which is what is required for fire suppression. If you are flowing a reduced GPM, then it is impossible to be attacking the heat side of the fire triangle and making progress. You are displacing O2, not reducing the heat, just like an indirect or fog attack. The flame itself might go out quick, but the heat is definitely still there. And I don't want to speak for anyone else, but having a hoseline charged with so much pressure that you slide backwards from the nozzle reaction doesn't sound safe to me, especially in areas of reduced staffing. If your going inside, take a high volume, low pressure hoseline and nozzle combination that will put fire out the quickest BY REDUCING THE HEAT and not pushing fire through voids and into what WERE tenable spaces before the fire dept showed up. Visit the NIST website and get on board with the rest of the fire service that isn't even measuring fires in BTU's anymore, but megawatts of energy being released, because of the exponentially increased fire loading of today. And if a 2.5" is overkill for any fire that isn't industrial, than I guess we've all been doing it wrong for the last 350 years. Or maybe you've never been more than 2 stories above the ground in an IDLH fire environment.

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