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Thread: Why CAFS?

  1. #61
    Forum Member Bones42's Avatar
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    2 separate occaisions I watched guys on ground ladders open a CAFS line and get blown off the ladder.

    Ya, I guess I'd blame the operator and nozzleman but those 2 times left a huge negative in my mind.

    But for us...there simply is not enough need for the system. In a busier area...I'd probably consider it more.
    "This thread is being closed as it is off-topic and not related to the fire industry." - Isn't that what the Off Duty forum was for?


  2. #62
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    [QUOTE=oper77;1295722]I am pro cafs. I have used it on class A fires many times.

    I ride with a new company.

    Next week we plan of going to the academy, and doing a fuel pad fire simulation. I understand from a Deputy Chief a sister company or two will be bringing CAFS Engines for us to "demo"

    Question for the group, what do I need to know about CAFS on liquid fires?

    Never worked with it on a liquids fire, I am assuming a thicker, blanketing foam is best, start at one end and try to cover the entire liquids pad, offering a blanket, trying not to disrupt the blanket, and try not to forcefully apply the foam so not to disrupt the underlying liquids.

    Anyone have some wisdom they can share[/QUOTE

    An important characteristic of Class A foam is that it will bond with anything that is carbon-based. This is where Class A and Class B foams differ. Although Class B foam reduces the surface tension of water, it repels carbon. One reason Class B foam works on a liquid hydrocarbon fire is that it floats on top of the fuel. Because Class B foam doesnít bond with carbon, it is not as effective on Class A fuel fires.

    Class A foam can be effective on small scale Class B fires if you use an air-aspirated nozzle or compressed-air injection system to apply the foam in a thick layer of bubbles. This will isolate the oxygen from the fuel just like Class B foam. Class A foams do not meet national standards for use with liquid hydrocarbon fires, which require them to be able to contain hydrocarbon vapors for at least 15 minutes. Because of this time factor, although applying Class A foam to a hydrocarbon-type fire will extinguish the fire, it will not suppress the vapors for long; they could reignite if a heat source is present. However, applying more Class A foam will work until the Class B foam operation is set up. When available, simply begin to apply the Class B foam on top of the Class A foam when adequate supply is established.

  3. #63
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    Hi All,

    RFD21C, let me try to answer your CAFS questions.

    You say that you crew was flowing 100GPM. I am trying to figure out what effects the reduced GPM flow of the handline has in regards to structural firefighting. The way that i understand it the reduced surface tension of the water increases the amount of BTUs that the water can realisticly absorb. So a fire that with plain water would require a 200 GPM flow would only reguire a 100GPM flows (numbers just made up). Is that correct?
    BTU's are simply absorbed more efficiently in a CAFS attack because we are absorbing them differently compared to water only attacks. In a water attack we are absorbing BTU's with solid drops of water. A solid drop of water only has the ability to absorb BTU's on its perimeter. Where as in a CAFS attack we are flowing air bubbles carrying water on each of the bubbles' perimeter. It is a hollow bubble that is formed from solid water droplets. A solid droplet of water can make 5-7 bubbles. Each water portion or CAFS bubble created absorbs BTU's. They are all stuck together in a honeycomb pattern as they are discharged from a straight bore nozzle. CAFS bubbles are very tiny, small uniform bubbles (10:1 ratio) that pop at approximately 140 digress. Some outer bubbles pop and others protect the inner/core bubbles which make it to a surface, then pop and release the water they carry which absorbs quickly into what it is applied to due to reduced surface tension cause by the class A foam (soap). When plain water hits the surface it is applied to most of it beads up and runs away because of hi surface tension. So we flow a higher GPM, in a plain water attack, to compensate for the inefficiency of the plain water.

    In the late 1990's Robert Taylor wrote a white paper for the NFA on the topic of CAFS and limited manpower. He document waters inefficiency and CAFS pros and cons. It is a good source of information.


    I assume that the GPM flow changes based on how wet or dry the finished foam is. Is that correct?
    Yes, GPM is based on how wet or dry the finished foam is. We flow at a 2:1 ratio (GPM to CFM). You can only fit so much liquid/air into a given size hoseline. When you allow more air (CFM) into a hoseline GPM flow goes down. More water added (GPM) into the hoseline GPM flow goes up.

    My biggest red flag with CAFS is the lack of negatives about it. I find very little in regards to the cons or pitfalls of CAFS. As with anything in the fire service there has to be positive and negatives. Most of the info i read on CAFS read like a carefully constructed National foam advertisment. Or when you read the fine print the test performed was paid for and sponsered by a bussiness that has a special interest in CAFS. I find it hard to believe that it is the goose that layed the golden egg as it is often presented. Just my two cents.
    CAFS is not a "magic bullet" that will put every fire. It is a tool. A tool that in my opinion makes water more efficient and firefighters a little bit more safer during the fire attack. That cons as I see them with CAFS are usually related to misuse or miss application of it. Understanding what CAF is and how to use it isn't hard or complicated. Training with CAF is the simple secret. And learning about what it is and how it works.

    Hope this helps.

    Be safe.

    Chief Lou
    "Got Foam?"
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    I believe the quality of CAFS that allows the lower flow rates as compared to plain water, is the "stickiness" ( and that's a technical term, coined by ME, lol). IE, the finished foam sticks to fuel surfaces, unlike water, which runs off.

    The surfactant and carbon loving qualities allow it to penetrate, and be absorbed into carbon based fuels. (Charred wood, being very high in carbon, repels water.) This has the effect of not only cooling the fuels, but providing burn back resistance as well.

    Bottom line: CAFS makes more efficient use of water, allowing for a reduced flow rate, and less total usage vs plain water.

    One of the reasons for the high rate of flow we use, is that much of the water runs off. Water extinguishes fires pretty well, but due to it's high surface tension, among other things, it isn't very efficient. Thus the need for beefy flow rates. We also like to build in a healthy margin- just in case the fit hits the shan we'll have some extra flow available.

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    Chief Lou-

    Thanks for that explination helps. It does bring up another question in my mind.

    What effects does cafs have on the thermal layers in a fire compartment? since the CAF stream will absobe more heat more rapidly then a plain water stream is it resonable to conclude that more heat is going to be absorbed before hitting the burning material. thus inverting the thermal layers and increasing the steam production. For lack of a better example Fog versus straight stream. obviously the effects will not be to that extend. From my limited experience (2 fires) with CAF hose stream I did not see a difference. However both fires were self vented and no longer in a contained fire compartment.

    Whilie I understand the hands on training is critical to CAFS as with any tool in the fire service. I am interested in the more scientific effects of CAFS and how it relates to fire behavior. more for personal knowledge versus practical street knowledge. I like to understand the how and the why behind things.

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    Quote Originally Posted by RFD21C View Post
    Chief Lou-

    Thanks for that explination helps. It does bring up another question in my mind.

    What effects does cafs have on the thermal layers in a fire compartment? since the CAF stream will absobe more heat more rapidly then a plain water stream is it resonable to conclude that more heat is going to be absorbed before hitting the burning material. thus inverting the thermal layers and increasing the steam production. For lack of a better example Fog versus straight stream. obviously the effects will not be to that extend. From my limited experience (2 fires) with CAF hose stream I did not see a difference. However both fires were self vented and no longer in a contained fire compartment.

    Whilie I understand the hands on training is critical to CAFS as with any tool in the fire service. I am interested in the more scientific effects of CAFS and how it relates to fire behavior. more for personal knowledge versus practical street knowledge. I like to understand the how and the why behind things.
    I know this thread is a couple years old, but I'm trying to learn as much about CAFs as I can. We are supposed to order an engine within the next 4 years and I'm trying to find out more about how it works and the pros and cons. I've read through this entire thread and there was a decent amount of information. I know there is a study that is supposed to be released sometime this year in regards to CAFs.

    RFD21C how is your department liking or not liking CAFs?

  7. #67
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    Quote Originally Posted by Squad50FF View Post
    I know this thread is a couple years old, but I'm trying to learn as much about CAFs as I can. We are supposed to order an engine within the next 4 years and I'm trying to find out more about how it works and the pros and cons. I've read through this entire thread and there was a decent amount of information. I know there is a study that is supposed to be released sometime this year in regards to CAFs.

    RFD21C how is your department liking or not liking CAFs?
    Squad 50 where in PA are you?
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    Delaware County

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    Quote Originally Posted by Squad50FF View Post
    Delaware County
    Well shoot....We're in Montgomery County and we have even done burns with CAFS down on Calcon Hook Road before.....You're welcome to come up sometime, wish I knew this about a month ago when we did some live burns.
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    I'll have to take you up on that

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    Quote Originally Posted by Squad50FF View Post
    RFD21C how is your department liking or not liking CAFs?
    I personally do not have cafs on my truck. However the engine company next to me just put a cafs engine in service. From the coffee table talk I have heard from these guys and the other guys that have cafs. They actually don't use it. They just mix in the foam with out the air. They have had several mechanical issues with the cafs which has lead to increased down time for the rig. Over the past few years we have had a couple of injuries from cafs. One being the ff closed the nozzle and the increased reaction blew her off her feet and caused her to knock her head. The 2nd being a rear discharge pressurized with air from the compressor. The next shift the dpo removed the cap with a spanner without thinking to open the drain. The cap blew off and broke his hand.He is still out of work due to several complications and very might be a career ending injury. Which would end his 30 plus year career. Obviously he is not a huge fan. I still do not have a personal opinion on it yet. But in a few weeks we should catch a fire with the new engine next door so time will tell

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    Default Old school versus new school.

    I have yet to see a CAFS sytem yet the is KISS. Traditional foam when properly done can just as effective as CAFS. You can make traditional foam darn near CAFS if the right injection sytem and nozzle type.
    Last edited by SuperFire123; 07-18-2013 at 02:11 PM.

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    Quote Originally Posted by Squad50FF View Post
    I'll have to take you up on that
    If you want to set up a live burn down there and invite us down, I think we could be convinced to come down there and you guys can have some line time- I'm pretty sure we have some folks who are either new and need some extra training or some guys that need (our) required annual live burn. Inbox me or ChiefEngineer11 if you are interested.
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    Quote Originally Posted by Weruj1 View Post
    in the FWIW column..........we have a Foam-Pro around the pump system preset @ 0.4 % for attack and it gives us good knock down.......we dont use it on every fire...........and you are all getting GREAT deals on foam as we are paying more than that for Silvex (I think).......glad it works for you but for us it can get pricey.
    We have that on my POC dept. engines. Not everybody needs CAFS. Systems like Foam-Pro are much less expensive, and require less maintenance, and are easier to use. We have plenty of water where we're at, so foam is used when we NEED it.

  15. #75
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    Quote Originally Posted by SuperFire123 View Post
    I have yet to see a CAFS sytem yet the is KISS. Traditional foam when properly done can just as effective as CAFS. You can make traditional foam darn near CAFS if the right injection sytem and nozzle type.
    You must be using the big P systems then.

    We have a waterous eclipse CAFS system on our 13 yo engine. It has been trouble free and only normal maintenance has been required to keep it working fine.
    Some of the systems out there just plain are over engineered and have far too many components to fail.
    We did have a flow sensor go bad right after placing the unit in service back in 2000,but that was fixed under warrantee and the system has worked well since.
    We can go from wet white water to shaving cream with just a small adjustment and back to plain water on any of our discharges or deck gun at the flip of a switch.

    All depends on who designs & builds it.
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  16. #76
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    Quote Originally Posted by chiefengineer11 View Post
    One thing's for certain, as I and many others have pointed out in other discussions here: You will have to supply your CAFS lines from tank.
    Wrong.....
    Robert Kramer
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    Comments made are my own. They do not represent the official position or opinion of the Fire Department or the City for which I am employed. In fact, they are normally exactly the opposite.

  17. #77
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    Quote Originally Posted by RFD21C View Post

    With our new engine coming with CAFS I am against it. for the following reasons:
    1) it added 50000 to the cost of the truck
    .
    I think someone either lied to you or Pierce took you to the cleaners.
    Robert Kramer
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    Management is making sure things are done right. Leadership is doing the right thing. The fire service needs alot more leaders and a lot less managers.

    "Everyone goes home" is the mantra for the pussification of the modern, American fire service.


    Comments made are my own. They do not represent the official position or opinion of the Fire Department or the City for which I am employed. In fact, they are normally exactly the opposite.

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    Quote Originally Posted by MemphisE34a View Post
    Wrong.....
    I'd be interested in learning why you say that. Granted, it could be done from draft, too, or from hydrants with very low pressure.

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    Quote Originally Posted by chiefengineer11 View Post
    I'd be interested in learning why you say that. Granted, it could be done from draft, too, or from hydrants with very low pressure.
    Can't you just gate down your intake line? (just asking, I've never used CAFS other than a Tri-Maxx extinguisher)

  20. #80
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    Quote Originally Posted by chiefengineer11 View Post
    I'd be interested in learning why you say that. Granted, it could be done from draft, too, or from hydrants with very low pressure.
    I stand corrected - we just recieved a pumper with an on board proportioner. Evidently it is not a CAFS.
    Robert Kramer
    cell #901-494-9437

    Management is making sure things are done right. Leadership is doing the right thing. The fire service needs alot more leaders and a lot less managers.

    "Everyone goes home" is the mantra for the pussification of the modern, American fire service.


    Comments made are my own. They do not represent the official position or opinion of the Fire Department or the City for which I am employed. In fact, they are normally exactly the opposite.

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