Engine Fire Suppression?

[palehorse89]

Foam and chemical is used in refinery fires, to smother the fire. Water will allow the petroleum product to float on it and travel, spreading the fire. Just what I have seen in the 30 yrs, at the Refinery and annual fire training. I am speaking of what Mark touched on above, Diesel fuel and oil fire's due to ruptured lines in the engine compartment.

[Dr4Film]

There is a LOT of misinformation running through this thread.

To set the record straight Halon is still used in the US however Halon has not been manufactured since January 1 1994. Supplies that have been stocked up are still being used although there are some manufactures that are using the ECO replacement in their products.

What is Halon? How does it work? Is Halon Legal? Is Halon Safe?

Halon should NOT be used in RV diesel engine compartments as the size of the compartment is TOO large to be effective. It can be used in very small compartments such as the rear of the RV type fridge area. However, to get proper safety coverage it would require a multiple head trigger system as the rupture and subsequent fire that can occur from a fridge fire can start at various places in the rear of the fridge. Example, I personally know of one previous Monaco owner who had a Halon SS-30 mounted in his rear fridge compartment which never went off due to the fire starting higher in the compartment and the "flue" effect. See photos.

Now for engine compartments. The only truly effective fire suppression system to use is an AFFF system, NOT Halon or water or any of the other chemical units that are sold. What do they use on aircraft that have caught fire??? FOAM.

I have had one in my engine compartment since 2010 and thankfully have never had to use it so far.

Since my engine compartment is fairly small compared to the larger engines that are now used in coaches I chose the 3 liter SS-200-R4 with a remote head to install in my coach. See photos. If you have a large engine compartment I would go with the SS-300-R4 which has double trigger heads and 4 liters of AFFF. One caution in selecting the locations of the trigger heads is to stay away from the turbo side of the engine due to the extreme temperatures on that side of the engine.

Another Monaco friend in Washington State had procrastinated in purchasing and installing an AFFF engine fire suppression system which we had talked about many times. He subsequently lost his entire coach to an engine fire. Link to news article with photos and video.

Cruzer's suggestion to have an alarm which alerts you to activation of the AFFF bottle is a great idea. Mine did not come with one but maybe someday I will look into adding an alarm.

Do not have this happen to your coach!

Dr4Film ----- Richard

https://www.youtube.com/watch?v=WHvsn7LWSt0

[smlranger]

The AFFF system that Mac The Fire Guy sells is not hard to install. I have the two head system in my engine bay. One nozzle near the hydraulic lines going to the radiator fan and the other over the fuel injection system. Hope to never find out how it works.

[navychop]

AAAF is great stuff, used that heavily in firefighter training in the military. Had 55 gallon barrels of it all over the ship. I can't understand why it is so hard to find in stores.

[Dr4Film]

Simple answer, more expensive than the cheap CO2 chemical ones that you find everywhere including any new RV.

I removed all of my CO2 tanks and replaced them with handheld foam ones I purchased from Mac The Fire Guy.

The CO2 ones will cake up if not maintained properly and will be useless in an emergency. How many people actually maintain all of their fire extinguishers? My guess is less than 1%.

No worries with foam tanks except for checking the pressure gauge occasionally to make sure it hasn't lost pressure.

Dr4Film ----- Richard

[Gary.Jones]

I'll vote for science any day, when the "science" is good. I also tilt toward knowledge and experience in any discussion. I didn't refresh for new comments before i started this comment so my snarky comment is no longer needed so i am editing them out :-)

Gary

[Cruzer]

Those are not CO2 extinguishers. What you really mean are dry chemical extinguishers that are charged with nitrogen. They will pack up and the retardant is toxic and corrosive once heated. I removed mine as well and replaced with handheld foam extinguishers. CO2 extinguishers use compressed carbon dioxide gas and have that large horn on them. They actually will make dry ice when used and the CO2 removes the oxygen from the fire triangle and also cools the fuel, removing heat from the fire triangle. I have to think that a handheld CO2 extinguisher would be an even better choice than the foam because you can safely use it on a class C (energized electrical circuit) fire without worrying about a shock hazard. I may yet get one of those for the RV.

One other thing to consider is that the handheld foam extinguishers should be kept from freezing so if you winterize your coach for cold weather storage be sure to remove the extinguishers and keep them in a warm place until next spring. The automatic engine bay extinguishers are designed to freeze as slush and won't be damaged be freezing temps although they won't operate until they warm up. They will work again once they thaw out.

[Dr4Film]

Originally Posted by Gary.Jones

I'll vote for science any day, when the "science" is good. I also tilt toward knowledge and experience in any discussion. I didn't refresh for new comments before i started this comment so my snarky comment is no longer needed so i am editing them out :-)

In my science class I was taught that water was made up of two parts Hydrogen and one part Oxygen. So how does feeding a fire with misting H2O starve the oxygen to put out a fire?

It doesn't completely. In this YouTube video it shows how part of a staged fire was suppressed with misting water sprinklers. However the lower portion of the fire had to be put out with a water stream. Plus it took a LONG time to extinguish the upper portion.

Diesel fuel, hydraulic oil and whatever else you would find in an engine compartment that had caught fire would be snuffed out quickly using a blanket of foam versus using any misting water.

Both diesel fuel and hydraulic oil are catalysts to any fire so it is critical to snuff out the fire quickly.

Dr4Film ----- Richard

https://www.youtube.com/watch?v=kq8N-9TaoZc

[waterboy10]

Go to outsideourbubble.com to see his installation of a fire supression system in his coach (video). Pretty interesting.

[HarleyOutlaw]

Originally Posted by Dr4Film

In my science class I was taught that water was made up of two parts Hydrogen and one part Oxygen. So how does feeding a fire with misting H2O starve the oxygen to put out a fire?

It doesn't completely. In this YouTube video it shows how part of a staged fire was suppressed with misting water sprinklers. However the lower portion of the fire had to be put out with a water stream. Plus it took a LONG time to extinguish the upper portion.

Diesel fuel, hydraulic oil and whatever else you would find in an engine compartment that had caught fire would be snuffed out quickly using a blanket of foam versus using any misting water.

Both diesel fuel and hydraulic oil are catalysts to any fire so it is critical to snuff out the fire quickly.

Dr4Film ----- Richard

Fire Science 101, retired firefighter here.

Water turns to steam and expands causing a cooling effect, it does not smother the fire. Fire triangle = heat, fuel and oxygen. Remove 1 and fire goes out.

Bonus info.......Sprinkler systems, misting type included, are not meant to extinguish the fire but to contain it so it doesn't spread further than the initial area of origin.

Dry Chemical extinguishers, if left sitting, will let the retardant material "cake up". Not due to the pressure of the nitrogen used as a propellant but rather to the material being so fine. A rubber mallet applied vigorously periodically will fix the issue.

Not trying to be a jerk, just sharing my experience/training with all of you.

[RubiconTrail]

Good science...yes.

Since the hydrogen and oxygen have very strong chemical binds, they don't just come apart and start burning. Not sure you noticed, but we carry water around in our fire trucks to put fires out without worrying that they will magically "come apart" and start feeding the fire instead.

Halon has not been manufactured in the US since 1994, as far as I know, because it is a CFC. There are many Halon suppression systems still in place in specialty applications that use recycled Halon. Recycling is fine, as there is no way to get rid of the Halon other than simply releasing it to the atmosphere. Better to to keep it contained as long as we can. That being said, it isn't a good agent for open engine compartments because it will quickly drop below its 8% effective concentration in that environment.

AFFF stands for Aqueous Film Forming Foam. It is great stuff, and is designed to form a film on top of a pool of petroleum product as it is applied. The pool of petroleum product itself is not actually burning, the vapors released off the top of it are...the film prevents vapor release, this the fire is extinguished. It also has some value as wetting agent, as noted. It will not, however, expand like water will, and exclude oxygen in that manner, so you take the good with the bad on that one.

I would submit that in the absence of a pool of petroleum product under my engine compartment, I would prefer the expansion properties of water over the film forming properties of foam. I am not saying water is the only way and foam won't work. I'm saying evaluate the two extinguishing agents based on their properties and make your own decision.

The youtube video posted is of a demonstration designed to simulate an open "room and contents" (like a cubicle area of an office) with Class A combustibles, not an enclosed engine compartment with class C combustibles. The video was designed to show how residential/commercial sprinkler systems provide adequate fire suppression to create an egress route. That's what those systems are designed to do...egress, not extinguishment. The video does not apply to this discussion.

Diesel and hydraulic fluid are fuel and moderate accelerants, not catalysts.

Mark is correct, typical ABC extinguishers are dry powder (the suppressant) and nitrogen (carries the suppressant tot he seat of the flame). They will cake up, and should be removed from their bracket, the gauge checked for charge, and then inverted and shaken to prevent caking. Once one is accustomed to listening and feeling for it, it is easy to know when the cake is broken up. These products should be serviced every five years, and should have a current tag listing the service date and a tyvek ring around the neck indicating the five year life.

As noted, handheld extinguishers provided by motorhome and boat manufacturers are usually inexpensive disposable extinguishers. They will work, especially when new, but are not reliable over the long term.


Edit: also a retired FF, agree with Harley, though I'm obviously a little bit more verbose

[Gary.Jones]

For those of us boneheads that didn't know we were supposed to shake our extinguishers to keep them in working order, and assuming that our extinguishers may now be "caked", is there any simple strategy for loosening them up or are they junk (and don't advise me to get them refilled as the refilling costs more than buying new ones....)?

Is the rubber mallet the best way to go?

Gary

[HarleyOutlaw]

Originally Posted by Gary.Jones

For those of us boneheads that didn't know we were supposed to shake our extinguishers to keep them in working order, and assuming that our extinguishers may now be "caked", is there any simple strategy for loosening them up or are they junk (and don't advise me to get them refilled as the refilling costs more than buying new ones....)?

Is the rubber mallet the best way to go?

Gary

Periodically turn the extinguisher upside down and back up. If you don't feel the powder move, take a rubber mallet and hit the bottom until you feel the clump fall. Then shake it up.

Typically the ones they put in RVs are not refillable. If it has a plastic handle and valve assembly its use and dispose. These are fine as long as the chemical is not caked up and the gauge is still in the green.

Hope that helps.