BAC Forum
General Boards => Technical Support => Topic started by: Joel Ashley on August 19, 2011, 11:04:47 PM
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Pete and Connie-
I hope after what happened to Wally and Iris that you install an automatic fire suppression system in the engine compartment before you drive off after the engine overhaul.
-Joel and Lee
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Dear Joel,
Seriously thinking about it. Thanks for the concern. Yes, it is somewhat scary after what happened to Iris and Wally. We have a Cummins engine and they had a Cat 2308 (I think). Different engines but potential problems everywhere. We do have faith in the facility here in north Madison. So far they have been very helpful, forthcoming with information and have showed us all the damaged parts and the problems associated with the parts. We are in contact several times daily. Keep us in your positive thoughts and prayers. Beaver hugs, Connie B.
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I hear you Joel, I keep telling my wife I want to get a fire extinguishing system installed in our engine compartment. Now I just need to get it done before I find myself saying, I knew I should have done that! We did get the little unit for the fridge, now the engine compartment. Do you know if Beaver Coach Sales or some other service place does those installs?
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I'm sure that BCS could do the job, Larry. But in theory you can install an engine fire suppression unit yourself without too much trouble. Mac The Fire Guy's website should be of some assistance, and if you happen to be in Oregon, which is where I think his office is (and he's not out doing seminars at a Rally somewhere), he could install one for you.
Like you, I've been thinking about an installation for our engine compartment for years and don't want to regret only thinking about it. I've got small Coldfire extinguishers as well as large standard ones in six places inside and outside my coach, all in unlockable bays or open areas. No matter where I am, I should be able to get to one or more of them quickly. But I can't get to the fire as fast as a built-in unit can.
http://www.macthefireguy.com/fire_safety_products.htm
-Joel
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I thought that the conclusions that installing one in the engine compartment was of not much value because of all the air spaces surrounding the engine/compartment. Did I misunderstand the prior discussion in this forum??
REFRIDGERATOR COMPARTMENT --YES........Engine ---no.
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Unless you have a system that shuts down your engine before the fire supression you may want to avoid an engine bay supression system. I'm not sure how effective one could be anyway with the vast amout of open space we have in coach engine bays. In the marine industry these systems are common place. Obvioius a fire on the water can be much more life threatening than on the road. The marine systems will shut down the engine first and are sized based on the size of the engine room that is much more closed to outside air than our RV. Some supression agents can cause a diesel engine to run away if the agent can get into the engines intake system. I know our air intake systems draw air from outside the engine bay. I'm not confident that would be the case if there was a fire near the intake hoses.
My vote is NO for an engine bay fire supression system.
Gil
08 Contessa
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I'm sure that BCS could do the job, Larry. But in theory you can install an engine fire suppression unit yourself without too much trouble. Mac The Fire Guy's website should be of some assistance, and if you happen to be in Oregon, which is where I think his office is (and he's not out doing seminars at a Rally somewhere), he could install one for you.
Mac is currently at the Escapees rally in Gillette WY. He looked at my engine compartment today and the installation will be easier than I thought. I'll probably do it myself.
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You might want to discuss with Mac the concerns that Leah and Gil proffered, Joel. I've heard that arguement before, and am not sure we shouldn't give serious attention to it and its validity before buying and installing a unit. I for one would be interested in his response.
-Joel
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If you are contemplating putting a heavier than air vapor extinguisher (Halon type extinguisher) in your engine compartment, you will most likely be unhappy if it is ever needed. The type that might provide you a chance at extinguishment of an engine fire is a multi-purpose dry chemical extinguisher with multiple nozzles to cover the area with agent. Multi-purpose chemical tends to partially melt and stick to the hot parts and then extinguishes the fire with a smothering type action. (it also helps chemically interupt the chain reaction of fire which is the fourth side of the fire tetrahedron but that's probably too involved of a discussion for here) By sizing the extinguisher to put enough agent into the compartment to make the cloud penetrate everywhere, you have a pretty good chance of success.
The maintenance on such an extinguisher would be problematic. Because of the size of the particles, around 25-75 microns, it tends to pack down even though it is siliconized to help prevent that from happening. This is why you should turn your portable extinguishers upside down and make sure the powder is loose every month. How many people do that with their portable extinguishers now, and imagine how many would unbolt a tank with 40 pounds or so of agent and flip it a few times every month.
For my money, and effort, I'd rather keep my engine compartment clean and leak free. Clean engine compartments don't often catch fire. Leaks are easier to see when they are small. The engine runs cooler without a layer of crud. Chafed wiring is easier to see. Carry an adequate number of portable extinguishers and you'll also be able to take them somewhere else, another coach or building. Just some thoughts.....
Ken
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Ken, were you talking about an AFFF type extinguisher for the engine compartment? Don
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AFFF is Aqueous Film Forming Foam, also a good extinguishing agent, but the three dimensional aspect of your MH engine compartment makes it difficult to insure that it will be dispensed on the area on fire and stay on the area that is burning. AFFF runs off of vertical surfaces. AFFF typically is used to form a "seal" over the top of liquid fires and extinguishes by smothering and cooling to an extent. AFFF typically comes as a concentrate to be mixed with water on use at either 3% or 6% depending on brand and whether the liquid fuel is a polar solvent (ethanol gasoline is the most common). It can be premixed put should be agitated occasionally for optimum performance. AFFF also helps water to penetrate into items by breaking the surface tension. So for couch fires, beauty bark fires and things like that it is often used although its main use is petroleum fires.
High expansion firefighting foam would be a great agent for motorhomes if one had the room and always carried enough water for it's use. It is excellent for filling spaces with cooling foam and excluding air. It was used for basement fires and other confined areas prior to the invention of better turnout gear and other firefighting tools. I presume some fire departments still use it, but it isn't very common in my area any more.
CAFS is a newer type of delivery system that uses compressed air to aid in the delivery and the expansion of the foam product. Tri-Max is one supplier of those systems. Again the problem with these systems is having a nozzle to deliver product to everywhere that could be on fire and keeping the foam on there. I did a search and didn't find any video of an actual engine fire extinguished by their system. They have 2 videos on their site of systems on engines, and one of an interior car fire, but they didn't light either of the engines on fire. Both engine compartment videos show areas of the engine compartment that don't get foam coverage. The interior fire shows the firefighter attacking the fire from multiple angles, and moving the nozzle to many different angles to eventually extinguish the fire, not at all representative of a fixed system. Perhaps someone knows of a video of an engine comartment on fire where they show the system extinguishing the fire.
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You might want to discuss with Mac the concerns that Leah and Gil proffered, Joel. I've heard that arguement before, and am not sure we shouldn't give serious attention to it and its validity before buying and installing a unit. I for one would be interested in his response.
-Joel
I'll speak with him over the next couple of days and let you know his response. There appears to be some confusion here, since I know he does not recommend halon for engine compartments for the reasons stated. I'll let you know what he says about foam or other agents affecting engine operation, etc.
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I spoke with Mac yesterday about some of the concerns expressed here and I also witnessed an hour-long fire safety demonstration he conducted. He does use AFFF foam in his engine compartment extinguisher systems and after the demonstration I have absolutely no concern about its ability to handle vertical surfaces. According to Mac the problem is that some inexpensive AFFF extinguishers are filled with such low-concentration foam that they don't have enough substance to cover vertical surfaces. The relatively inexpensive extinguishers Mac demonstrated for RV use have 10% foam and they performed quite well on both vertical and horizontal surfaces. The heavy-duty extinguisher he also demonstrated had foam so thick you could frost a cake with it.
As for the issue of boats having an engine-kill before the extinguisher is used, he pointed out that wasn't practical since many fires occur while the vehicle is in motion and killing the engine would make steering and stopping difficult. He said that engine runaway is not a problem with AFFF because it has no combustible hydrocarbons so is inert in the engine even if ingested by it.
After Mac's demo and discussion of fires in DP's, both my wife and I agreed we would purchase an engine compartment system.
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Cool. Let's hope now that you never use it.
Ken
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I have also watched one of Mac's presentations and am thinking about buying one of his systems.
Is there a chance that he would attend one of our intentional rallies? It might be well worth his time.
Maybe we could get him to put together a kit with hoses and nozzles that would fit many of of our coaches.
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Assuming that he has a website, does he have any information on it regarding this system....anybody know?
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I'm curious as to how effective the system would be while the coach is moving at speed. There's a lot of air passing through the engine compartment. I'm not expert, but would think extinguishing agent will have a hard time getting to where it needs to be. Did he make any comment on what the extenquisher agent does if ingested by the engine?
Gil
08 Contessa
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If I was going to install an automatic 3 or 4 liter fire supression system in the engine compartment I would also be inclined to install an extinguisher alarm system or a heat sensitive alarm set to trigger at no more than 275 degrees. The idea is to get the rig stooped as quickly as possible to maximize the effect of the fire supression system.
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Gil -
Quoting Joel W., "He said that engine runaway is not a problem with AFFF because it has no combustible hydrocarbons so is inert in the engine even if ingested by it." That it is inert, beyond not being combustible, likely means it does little harm inside the engine, but it is a question worth further exploration.
Leah-
http://www.macthefireguy.com/fire_safety_products.htm
Scroll about halfway down to the engine compartment units, as well as an available alarm.
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One of the reasons boats have engine kill in the automatic fire suppression is to save the engine. Dry chem extinguishers will ruin your engine if ingested. So if you don't put an engine stop function in, be sure the extinguisher you use is not harmful to the engine, as it WILL be ingested.
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AFFF concentrate is mixed with water to create the "foam solution" then aireated at the nozzle to produce "finished foam". If he's using a 10% mixture ratio to create more foam, it's still 90% water. Unmetered amounts of water/foam into the intake of a diesel engine can't be good for it. When water converts to steam inside the engine it expands 1700 - 1. I'm not sure which engines can survive that compression ratio. It may not add to the combustion, but it will certainly alter the compression.
You will not get off scott free from damage in any event. The engine will most likely be hot when/if a fire starts, unless it's an electrical fire, which AFFF solution isn't going to extinguish anyway. Imagine dumping a few gallons of water on top of your hot engine. It's still better to put the fire out than it is to burn the entire motorhome, but there's gonna be some damage.
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[quote author=]
You will not get off scott free from damage in any event. The engine will most likely be hot when/if a fire starts, unless it's an electrical fire, which AFFF solution isn't going to extinguish anyway. Imagine dumping a few gallons of water on top of your hot engine. It's still better to put the fire out than it is to burn the entire motorhome, but there's gonna be some damage.
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Even a rebuilt engine is a lot less $$ and hassle than replacing everything in the MH.