Thread: Questions about CAFS
01-24-2001, 11:53 AM #1TowerLadders ForeverFirehouse.com Guest
Questions about CAFS
Ok folks I'm a dummy don't know anything about CAFS, how does it work , how do you get more firefighting out of gallons of water. You folks get the idea I have heard of CAFS but can't find much info on how it actually works can anyone help me out.
01-24-2001, 12:34 PM #2Capt. LouFirehouse.com Guest
HI, This is the a basic overview of what CAFS is and how it is utilized. If you any other specific questions do not hesitate to ask.
ALL ABOUT C.A.F.S.
WHAT IS CAFS?
Ø It is a complete system consisting of a foam concentrate proportioner, water pump, and air compressor.
HOW DOES IT WORK?
Ø Compressed air is injected into the hose line just past the point where foam concentrate is added. Both foam and air are injected on the discharge side of the pump. Thus creating very small, uniformed bubbles.
WHY ARE CAFS BUBBLES BETTER?
Ø CAFS produces uniformly sized, small foam bubbles that are very durable.
Ø It increases visibility in a fire situation since the CAFS produced foam adheres to the fuel source and does not vaporize as quickly and turn to steam like water.
Ø The excellent penetration of CAFS foam stops combustion that enter the atmosphere.
Ø CAFS enables faster absorption of heat, thereby reducing the temperatures in the firefighting environment much quicker.
WHAT ARE THE TACTICAL ADVANTAGES?
Ø The use of CAFS for structural firefighting creates improved conditions for attack crews.
Ø The reach of the fire stream is considerably longer.
Ø CAFS produced foam adheres to the fuel surface and resists heat longer than low solution hoselines.
Ø Hoselines containing CAFS are at least 50% lighter than conventional water or foam solution hoselines.
Ø CAFS utilizes smoothbore or ball valve nozzles.
Ø Uses less water to extinguish a fire, thereby reducing the amount of water damage to a building or structure.
Ø Excellent exposure protection by applying a dryer foam concentration to a structure.
HOW MUCH FOAM IS USED TO MAKE CAFS?
Ø A very small amount of foam is injected into a hose stream for interior fire attacks because it is turbo-charged by the air, thus the ratio is .3% of Class ‘A’ foam to 99.7% of water per 100 gallons product.
HOW DOES THE USE OF CAFS AFFECT MY WATER SUPPLY?
Ø Using CAFS increases the flow duration of an attack line. For example, a 600-gallon booster tank could be equal to A 1200 TO 1800 gallon booster tank, when using CAFS.
CAFS makes water much more efficient!
DO I NEED SPECIAL HOSELINES TO USE CAFS?
Ø No, CAFS uses the same hose lines as used for water attack lines.
01-24-2001, 12:56 PM #3N2DFireFirehouse.com Guest
Thank You for an excellent overview of how CAFS works. I find myself in a similar position as TowerLadders Forever in that I am not very well versed on CAFS.
I do however know enough about it that I think it would be a wonderful addition to my departments front line engine since we are very rural & must haul our water with us about 95% of the time.
My question - to all knowledgeable readers is - How hard is it to retrofit an existing piece with CAFS ? and if anyone else has gone down this road - what are some things to watch out for ?
Take Care - Stay Safe
01-25-2001, 09:56 AM #4Gregg GeskeFirehouse.com Guest
I am in the process of retro-ing my pumper this year. You need space, PTO opening, and foam system. It could be considered hard or easy depending on the apparatus. Please contact me if you have any questions about adding CAFS to an existing apparatus.
01-25-2001, 09:02 PM #5Capt. LouFirehouse.com Guest
As Gregg stated you need lots of room, space and a trans that can except additional equipment. I would check with a CAFS company such as Pnuemax to see if your rig would be able to be retrofited. The units are not cheap. $30,000.00 to $40,000.00 dollars to do aftermarket installs. Don't let the cost deter you. It is money well spent.
01-26-2001, 09:16 AM #6mike021Firehouse.com Guest
I'm not to familiar with it. but we are having it installed on the new engine we are buying. I have heard it is very usefull. Expensive but worth it.
This is your brain... Pierce
This is your Brain on drugs..... E-One
01-26-2001, 10:07 AM #7N2DFireFirehouse.com Guest
Thanks all for the replies thus far. Any additional info would still be greatly appreciated.
I am currently in the process of building my argument for having CAFS in the first place. Since we will not be due for a new truck for quite some time now - a retrofit would be my best option. As soon as I can make my case for having CAFS I will be contacting the Rep who sold us the truck (It's a KME if anyone cares ) first to get their opinion of adding a CAFS system. After that I will seek input/bids from other 3rd party installers.
Wish me luck - I have a long,hard,uphill war with a lot of "We never had it before, why do we need it now?" people.
Take Care - Stay Safe
01-27-2001, 11:42 AM #8TowerLadders ForeverFirehouse.com Guest
Thanks for the info folks, I agree its hard to get the folks to change to new things. I remember when guys balked at the scba, we,ve been fine without it I was told, go figure. They all learn at some point.
02-02-2001, 03:48 PM #9pvtcfd22Firehouse.com Guest
I am a little confused. (This is not so unusual a condition for me, however)
If the caf stream reduces the obscuration of visibility by slowing the creation of steam, how is it possible that the caf stream also reduces the temperature of the environment more rapidly as well? This would appear to be a physical law being broken. Water reduces the temperature of the atmosphere by vaporizing. If the caf stream by it's nature slows water vaporization, then how can it speed up the temperature drop?
I am not sure how the caf stream would work, is it interupting the chemical chain reaction similar in nature to a dry chem extinguishing agent, or smothering by it's foam bubble blanket? It just seems like physics come into play somewhere here and I have not caught on to how the improvement works. I am not trying to be a wise guy, believe me, just the opposite. We are presently considering adding a cafs to our new truck. One advocate suggests that we can do away with a 1500 gal tanker once we get it, and I am not convinced yet. I am playing devil's advocate I guess. It only makes sense that it the hose is charged with water + compressed air, than the water tank will last longer. But the flow rate is reduced, that is why it lasts longer. I could use a smaller bore tip and achieve the same results. So how does it work? How does it effect the flow rate formulas and is the critical flow rate reduced?(by using caf)
I have also read a study that showed that caf streams are LESS effective in an indirect structural fire attack. So I guess it would also depend on your standard methods for the department.
I am certainly wishing this is as good as it is advertised, but need to hear all aspects of the debate to be convinvced. So please try to convince me!
Lt. Paul Berry
02-08-2001, 04:25 PM #10Gregg GeskeFirehouse.com Guest
Except for what Capt. Lou printed I do not recall reading too much that CAFS reduces temperature quicker than plain water. Class A foam is in theory, quicker, than plain water because of the increased surface area. A quick knockdown does not necessarily reduce temperature quicker. I have a copy of a study done by the University of Canterbury, Christchurch, New Zealand, that compares heat release rate of 3 different agents, CAFS, plain water High Pressure Delivery, and HPD with foam. The heat release rates were very similar for each. Knockdown times were quicker for the CAFS. It is still the water that is extinguishing the fire; it is the method that the water gets to the fuel that is different. For structural firefighting with CAFS we used to hear 1GPM water/foam per 1CFM of air, now that has increased to a minimum of 2GPM water/foam per 1CFM of air. From my own experiences you do not notice the heat as much because you do not get the steam blast that you usually get from plain water. An interior attack with CAFS has to be done in unison with ventilation. The tactical advantage of the CAFS is that the finished foam is somewhat insulated from the heat as it travels through the air to the fuel, once on the fuel it adheres and does not run off unlike plain water. I have never found anything on the changes to the flow rate formulas and the critical flow rate. CAFS is reported to be 5-7 times more effective than plain water. I do not know if you can divide by 5 to obtain correct flow rate. Brainerd, MN had a fully involved, attached garage fire on 2/1/01. With CAFS they knocked down the fire, did overhaul and flushed the lines using less than 200 gallons of water (and had no rekindles). Because you would still need the carrying capacity of your tanker for your ISO rating?, I do not know that it would justify getting rid of it by purchasing CAFS. Regarding the effectiveness of indirect attacks, it does work very effectively on indirect attacks. With the added energy of the air you do get further reach. I have seen it work very effectively on basement fires through a small window. I have got a collection of articles on CAFS I would be happy to send you if you are interested. I do not know if I helped convince you or not, but I for one am convinced.
02-14-2001, 09:51 AM #11Capt. LouFirehouse.com Guest
With regards to my comment regarding temperature drop of CAFS compared to water. Published in Fire Engineering in February, 1993 issue was an article entitled
"Quantifying the effects of class A foam in structure firefighting" written by Dominic J. Colletti. It was about what is known as the "Salem Tests". The short and sweet of it was that CAFS was 480% more effective than plain water and water as foam solution was 110% more effective than plain water in working to lower room temperature. Here is a copy of the chart that was included in that article. It shows the drop in temperature and the rate of that drop per second it took to go from 1000 degrees to 212 degrees at the four foot level.
Water took 222.9 seconds or 3.5 deg. per/sec to drop the temp.
Foam solution took 102.9 seconds or 7.6 deg. per/sec to drop the temp.
CAFS took 38.5 seconds or 20.5 deg. per/sec to drop the temp.
I've said it before and I'll keep on saying it, CAFS is incredible and it works very well. It is a definite advantage to the firefighters on an interior attack. Training with and understanding CAFS is the key. Class A foam applied with CAFS does not replace water, it enhances it.
Hope this gives you a better understanding of the heat absorption advantages of CAFS. I would suggest that you read the article.
[This message has been edited by Capt. Lou (edited 02-14-2001).]
[This message has been edited by Capt. Lou (edited 02-14-2001).]
02-14-2001, 02:31 PM #12Gregg GeskeFirehouse.com Guest
Thanks for the information. I will try to obtain a copy of the article for my CAFS article collection. I am somewhat familiar with the Salem tests and the controversy about basis for true quantitative comparison. Examples: Identical fires in identical structures with identical fuels, the identical drying history of the fuel and identical attack and nozzle techniques. Apparently this has yet to be done. Looking forward to always using CAFS, now that our city has approved the budget for our retro-fit.
02-22-2001, 09:55 PM #13CainFirehouse.com Guest
We are thinking of converting a mini pumper to support a CAF system. We do not respond to structure fires only MVA's and this truck would be exclusively for vehicle fires. Has anybody done this? Does anybody have any thoughts, pro or con, on CAFS for vehicle fires?
Remember plan "B"
02-23-2001, 01:24 PM #14mike021Firehouse.com Guest
I would recomend on not waisting time and money on a CAFS for vehicle fires only. The vehicle will be a total loss anyway. we are getting a CAFS on our new engine and we won't be using it on vehicle fires due to it being a loss anyway and it's not worth us spending the money on foam to waiste it on someting not worth a damn after the fire is out anyway. anyone have a different opinon please i would like to see any point i may be looking over. cya!!
02-23-2001, 04:54 PM #15Capt. LouFirehouse.com Guest
Glad to here your considering CAFS. The money would be better spent on a class "A" pumper rather than the Mini. Regarding putting CAFS on the Mini, I agree with mike021 that it would be a waist of money on a mini for car fires only. A neighboring town has a CAFS on on a Mini, but they are using it for all types of fires including interior attacks. They are a rural community and it works well for them.
CAFS works well for all types of firefighting. We use it on car fires. When operating CAFS at .3% injection rate, you are using pennies worth of class "A" foam for car fires. YES, Class "A" foam works great on car fires! We put a fog nozzle on the handline, while flowing CAFS. Yes, it strips the bubbles from the handline, but it reduces the nozzle reaction force and still gives us a lightweight, water efficient handline that expels a nice, milky product. We put out fully involved car fires with less than 250 gallons of booster water. When out on the highway with no hydrants in sight, its a benefit. Plus we only have to commit the 1 engine to the highway for the car fire.
Hope this helps.
02-23-2001, 09:02 PM #16CainFirehouse.com Guest
Thanks for all the great comments both for and against. These will go a long way in helping to decide what to do.
Now I have another question; but first some background info on what we do.
We are a Highway Rescue department and we respond to MVA's in rural areas ONLY. We have no access to hydrants and the truck currently has a 200 gallon tank. We purchased the truck used because of a particularly nasty call that involved two vehicles on fire with people trapped.
Okay, my question is what would you suggest as an option for configuring this truck. We probably have about $10,000.
Remember plan "B"
02-24-2001, 12:49 AM #17FEOBobFirehouse.com Guest
My department recently installed a "portable" CAFS on the engine cowling of our (older) tillered ladder. it measures around 2'x2'x4', has 40 gallons water, and a compressed air cylinder. It was put on this rig specifically for auto fires. It has done well in training fires, but to my knowledge has not been used in actual incidents. It is in a station with an engine, and their plan is to take the ladder with the engine to use the ladders CAFS to evaluate. I'll try to get more info and edit it into this posting.
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