Halon Fire Supression Systems

[Edie and Marty Hochberg]

I have noted over the past few months a number of references to halon fire suppression systems in engine compartments.  I feel a comment on these is in order, although I must also note I am not a fire safety specialist.

I suppose installing them in compartments behind refer systems is fine.  However, regarding their installation in engine or generator compartments I suggest they may not be effective.  Halon systems are commonly used in the marine setting, in engine or machinery spaces (rooms).  In those locations they are typically interfaced with engine, electrical and ventilation system shutdowns.  This is because if the source of the fire (fuel or electricity) is not eliminated the fire will restart as soon as the halon dissipates.  The ventilation systems for these spaces are stopped, of course, so the halon does not dissipate before the fire is extinguished.  If a fire starts in my engine compartment I do not want my engine to be killed immediately.  I want to get to the side of the road so that my family can leave the coach pronto, but not get hit by other vehicles.

Regarding engine or generator spaces I can not see any coach carrying enough halon to effectively stop a fire because the heavier than air halon will immediately drop out of the engine or generator compartment.  If the coach is moving the dissipation will be instantaneous just from the normal amount of air circulation in an engine compartment.

Regards,
   Martin Hochberg

[LarryNCarolynShirk]

I was wondering about the effectiveness of Halon in an open bottom compartment.  You make some good points.  Thank you Marty.

Larry

[Richard And Babs Ames]

We carry a couple larger fire extinguishers rated ABC along with the dinky one that came with the motor home. Not automatic but something at a reasonable cost.

[Jeremy Parrett]

So.....your engine compartment is on fire....... the engine will probably run until the fire eats through the high pressure diesel line, by which time your coach will be history......do you not think ANY auto fire suppression system might just buy you enough time  (after you have driven off the road and baled out the family) to isolate the  batteries, shut off the propane manually and follow up with some CO2, to really cool things off, until the fire department arrive ?  Halon will NOT stop the engine.  The Air intake is external.

[Robert Mathis]

I love Halon systems. I have had them on several boats, but Halon kills the fire by depriving it of oxygen. The open bottom, side and rear of the engine compartment on the motorhome will completely defeat the one pound bottle of Halon. I agree it is a good idea for the fridge, but I think it's a waste of money for the engine compartment. The system in my last boat, with an enclosed engine compartment, was al least 10 pounds of Halon, and when it shut down the engines for lack of oxygen, all circulation in that compartment would be terminated. That's why they instruct you NOT TO OPEN THE HATCHES!. THere is far too much airflow thru the back end of a DP for that little bottle to work.

[Jeremy Parrett]

Until I can find a better solution for the engine compartment, I think 2 auto halon extinguishers are better than none.  Maybe foam is a better way to go?

[Ken Buck]

I presume that any fire in my engine compartment will burn until it is cooled below the point of ignition, fuel removed, oxygen removed or the uninhibited chain reaction of the fire is stopped.

I can't carry enough CO2 bottles to cool the C9 engine in my motorhome.

I can't carry enough Halon/halogenated agent extinguishers to make a continuous supply with the open engine compartment and/or a large fan supplying the oxygen if it is still running.

I carry 100 gallons of water, but don't have a supply system to apply it in the quantity needed to extinguish anything but a small fire.

I do carry multiple small hand extinguishers with powdered agent that 'melts' onto and has a tendency to cling to hot surfaces. These are multi-purpose dry chemical extinguishers with hoses so that the agent can be directed onto the area needed. I also know how to disconnect my batteries to help stop the wires from glowing and reigniting the fire.

I've been to literally 100's of vehicle fires, from old volkswagons with the engine castings where the metal would actually burn, semi trucks, motorhomes, cars, pickups and virtually everything else that can and does catch fire. I've used different kinds of fire extinguishers on hundreds of fires. Depending on the size of the fire, some were effective and most were not due to size or environment. I wouldn't waste my money on a halogenated agent or CO2 system in an area that isn't confined. Small hand held halognated agent and CO2 extinguishers work very well inside motorhomes where the environment is controllable. They are nice inside because they are easy to clean up after. In my opinion they are useless in the engine compartment of my motorhome.

Sometimes you can make a difference with multiple dry chem extinguishers if you use them promptly and properly. In my opinion they are your best option.

I did not stay at a Holiday Inn Express last night, but I did go to work for 31 years at a large metropolitan fire station. Your mileage may vary, don't believe anything you read on the internet, and only believe half of what you see with your own eyes.

Ken

[Jeremy Parrett]

Ken,
  Good information.  I have 2x 10 lb dry chemical extinguishers . They might be more useful than either halon or CO2 from what you are saying.  I am an ex Royal Navy Submariner and fires were one of the things (Russian subs were another)   we had to be right on top of at sea. Water was our first line of defense once the current was cut off.......even on diesel fires using a spray at the base of the flames.
 Temperatures in the RV engine compartment are at least 140 deg F... ..or higher.  Maybe some kind of alarm system might be as effective as a built in system using halon?

[Ken Buck]

An early warning system is a great idea, but there are few suppliers of systems that are easy to install in a motorhome. My idea of early warning is the rear view camera which should show the black smoke of an engine compartment fire fairly early. I also have a remote temp sensing unit under the bed which is directly over the engine in my coach. I know most people use them to monitor outside temperature, but I have two so one is mounted under the bed. Monitoring the temp of that compartment might give me a heads up when something is amiss. Here's hoping I never find out if those two things work.

Not many options but to fight fire on subs. Fortunately you had a good supply of water.  

Ken

[Jeremy Parrett]

here is a link to a system called Cold Fire RV Systems.  
     Installed on an Allegro Bus......http://www.rvcruzer.com/firesystem.php
  Having reviewed all the info I am going with this system.