Engine Compartment Fire Extinguisher

[SmokingRocks]

UPDATE:
11/22/17 - I've decided to go with option 3 since I have most of the components to make this work.


Purpose:
Most vehicle fires start in the engine compartment and our old race car had a system on it so why not add a level of protection. My system is likely not going to fully extinguish a fire but the idea is to have it knock it down until I can respond with my 10lb CO2 unit.

There are three scenarios I can imagine where a fire would occur in the engine bay.

1. Nest or foriegn debris on / in / around the exhaust
2. Fuel Leaks, from rubber hoses or vent from tank
3. Electrical Short

Concept:
I found a 5 lb FE-36 (halon replacement) unit at a job site which no one claimed, so my wheels started turning. (Yes I am aware that 5lb unit is small for this application but it was free)

Option 1: Manual Activation from Cab

For this I would like two discharge jets mounted on the inside corner of each battery box. This would mean that the two jets would be focused on both sides of the engine. Which would help knock down all three scenarios.
PROS:

$$
Could activate system earlier than an Automatic System (in some cases)​

CONS:

I would need to be in the truck, notice the fire and activate the system
General coverage, not specific to actual fire location​

Option 2: Automatic Activation

5 discharge jets mounted strategically around the compartment. My thought would be each head would be activated upon detection in that location
PROS:

This design would be the most effective
Automatic deployment​

CONS:

$$$$$$$
System Under Pressure all the time, unless I add complexity
Potential for unintended deployment​

Option 3: Automatic w/ Manual Override

I have no experience with this but would love to have the ability to manually control it. I guess it would just require a valve separating the charged system from several uncharged jets. More costly than option 2.
​

 

[Mandrake]

*edit- never mind... have fun!

 

[SmokingRocks]

What I can tell you is that if you make it semi- automated, as in, it senses a fire and illuminates a light and sounds a buzzer and then you pull a handle, the fire will have far less chance to propagate than if you wait until you see smoke.

Totally agree, Can you suggest electronic fire sensors?

The extinguisher system in the C-130 works ny displacing oxygen inside the closed engine nacelles... with as much open area below and in front of your engine bay to allow fresh air in to reignite the flames, a 5 lb. bottle may not be enough.

I completely understand, this would be mainly to knock down the fire while I respond with my larger unit in the rig. If by happenstance it puts it out then sweet.

I'd set up a halo around the hood using an aluminum tube with holes drilled in it. That's what the C-130 uses; there are no nozzles pointed directly at specific aeas or components because again- the purpose is to flood the enclosed area with an inert gas.

Make the lever you have to pull very obvious and very easy to get to from other drivers or passengers seat. Use copper 0.020" safety wire to secure it to prevent accidental discharge (giggity).

An easier solution might be to just keep the oil off your engine and make sure any electrical work you do isn't garbage. Or, just keep a hand held extinguisher handy.

Yea I know the bay of the 80 is far from a sealed bay like those on big rigs and rear engines units. CO2, halon, FE-36 all work great in a sealed compartment, Halon and FE-36 will still work (albeit less effectively) in an unsealed bay O2 displacement is not their main mechanism of extinguishing fires. Which is why I am thinking of focusing the discharge on general areas.

Also agree about maintaining the rig and electronics but that wont stop a rabbit or mouse from making a nest inside of your intake manifold or exhaust manifold. My friend just had an engine fire under his fuel rail because of this exact scenario, luckily he was able to catch it in time but not before it destroyed his wiring harness, injectors and computer. Had he let it continue burning it would have burned through the fuel line, if that had happened the rig would have likely been a total loss.

Basically I've got the FE unit and I like to tinker.

 

[DirtScaresMe]

I worked on boats for a long time and engine compartment fire suppression was pretty common. Seemed easier though on a boat because it was an enclosed space so pretty easy to stop/displace the o2 supply.

 

[SmokingRocks]

Yea I know the bay of the 80 is far from a sealed bay like those on big rigs and rear engines units. CO2, halon, FE-36 all work great in a sealed compartment, Halon and FE-36 will still work (albeit less effectively) in an poorly sealed bay since O2 displacement is not their main mechanism of extinguishing fires. Which is why I am thinking of focusing the discharge on general areas.

 

[Dave 2000]

Pretty much every vehicle fire I have seen, the owner could not open the hood because:

The heat melted the hood release cable outer so unable to release mechanism.

Flames coming from grill area prevented fingers searching for safety release mechanism.

Fire reignited due to power still available from battery.

Sort those first IMO.

Regards

Dave

 

[half k cruiser]

@SmokingRocks the battery, main fuse box, and the fuel injection rail are the most common areas I've seen fires. In fact they are the only areas I've seen under hood fires start. Now, that doesn't mean that it doesn't happen elsewhere, for instance cars that are so burned up when we get there that you just really can't tell. In any case, maybe that helps with your nozzle location selection and maybe it doesn't.

 

[NLXTACY]

I have a Pegasus system collecting dust in my garage somewhere that I never installed.

 

[BILT4ME]

Maybe a shout out to FireFighters that see car fires and the most likely culprits. Fuse the battery and heavy electrical components, a discharge over the catalytic converter in the case of a brush fire.

@Dave 2000 makes good points about not being ABLE to access the fire under the hood in most cases. MAYBE your system will allow it by knocking it down fast enough.

Also, I know in the industrial market, fire safety systems must be regularly tested for proof of operation. Would you set up a plan for that?

 

[DirtScaresMe]

Maybe some kind of cool pull cord (with a rubber handle) to disconnect the battery, available along the frame near the driver's side door or something like that. So you could remotely physically disconnect the battery.

With the "mud guard" flaps sitting in the wheel wells (between the tire and the engine compartment) gone you can get a pretty good angle up into the engine compartment, especially if you have a lift kit. I have a 10lb extinguisher mounted in the back compartment / cargo area, and my current idea was to basically take that and spray up into the compartment.

 

[SmokingRocks]

Maybe a shout out to FireFighters that see car fires and the most likely culprits. Fuse the battery and heavy electrical components, a discharge over the catalytic converter in the case of a brush fire.

@Dave 2000 makes good points about not being ABLE to access the fire under the hood in most cases. MAYBE your system will allow it by knocking it down fast enough.

Also, I know in the industrial market, fire safety systems must be regularly tested for proof of operation. Would you set up a plan for that?

Yea I plan on using a CO2 bottle to test the dispersion patterns and coverage, I don't have the money to test with the FE-36. I was doing a lot of research on this last night and it sounds like a chemical foam extinguisher would be better suited for our engine bays. I'm not that worried about it to go that balls out though.

Yes remote battery disconnects are essential.

 

[BILT4ME]

Yes remote battery disconnects are essential.

There is some country that REQUIRES external remote battery disconnects. So much that one of the members on this forum was complaining that at a stop light, some yahoo ran up, shut off his battery, and pulled the handle and took it with them and ran away so he was completely dead at the intersection. May want to think about that as well. I know race cars require it on the rear.

 

[artech]

On the multiple vehicle fires I have seen, the following seem to be common themes:

Hood latch becomes inoperable early in the incident requiring accessible prying or cutting tools to get hood open.
Under-hood fuel system components adding fuel to the fire(literally)as they degrade from the heat.
Often the electrical system fails completely due to the wiring harness or fuse box melting and running together, sometimes resulting in fuel pumps continuing to run despite the shutoffs in the system.
Cutting the battery cables does not always work- sometimes the battery has to be completely removed to cut the power.
Air bags can also remain energized and sometimes deploy without warning if the system is shorted out= not good.
Many cars have magnesium components that are difficult to extinguish without steam explosions that can be pretty dangerous.
Hood struts and other gas struts can explode from the heat and launch pieces a surprising distance.
Ethanol enhanced fuels are harder to extinguish than regular fuels and can even require different foam additives- similar to aviation firefighting.

And you cannot have too big of a fire extinguisher on hand. Many, many times we roll up and find a car fully engulfed and see several of the small hardware store dry chemical extinguishers lying on the ground (empty) from passerby that tried to help. One big extinguisher applied early and properly would have at least saved the vehicle contents even if the car was totaled.

For an onboard underhood fire suppression rig I'd recommend a marine-type CO2 system with a minimum of two nozzles, one on each side of the engine block. Four nozzles would be better. The system tank should be upsized due to the open engine bay on the LC but most boat engine compartments are vented anyway, so go up one extinguisher size for a similar cubic foot space and you should be in the ballpark. The tank will be rather large but it can be anywhere on the truck, even underneath if desired, and CO2 is cheap to refill, leaves no corrosive residue like the ABC types, and is non-toxic outside of an enclosed space. It also can handle freezing temperatures and still function. A good rugged battery disconnect somewhere would usually help, unless the fire has already shorted things out up front. Don't completely rely on it working when you need it in a crash or fire, but it might make a good theft deterrent as a little bonus.

Just my two cents, YMMV. Hope this helps.

 

[SmokingRocks]

good information @artech

I had though about using my 10lb CO2 extinguisher for the auto system which saves my FE-36 extinguisher for in-hand extinguishing.

 

[mingles]

Another area to think about an electrical disconnect should be your onboard solar system. At a dead short, most 100+ Watt panels are putting out 4-7 amps at 40-60 volts. That is enough to make a pretty strong spark/arc and can easily start a fire. That power is present ANYTIME the panel is exposed to daylight. An externally mounted disconnect may save your rig in case of a short. Commercial solar systems are required to have this by the National Electric Code, your vehicle should be no different.

I learned this lesson the hard way by burning a 26’ ft travel trailer to the ground in a runaway solar charging situation. The root cause was internal shorting in the battery bank, but the solar disconnect was inside the trailer and inaccessible due to the fire. All my vehicle mounted solar systems now incorporate an easily accessible, externally mounted, PV disconnect.

 

[bigredmachine]

Maybe some kind of cool pull cord (with a rubber handle) to disconnect the battery, available along the frame near the driver's side door or something like that. So you could remotely physically disconnect the battery.

if your going to do a battery disconnect it should be for both positive and negative, kill the power and the ground.

 

[SmokingRocks]

Here is a sketch of what I'm thinking. And I've got most of the parts to make this happen. Position 2 on the T is always open to the heads. Oh and the valve will be powered by my rear mounted isolated battery.

 

[zona]

I don't know if this point matters but fire extinguishers should not be stored where temperatures exceed 120' F, if this has already been stated, I second the point.

Zona

 

[SmokingRocks]

Yup I've found that out through research. I'm thinking of mounting a large CO2 tank between the frame rail and slider on the driver side. There is room there for quite a large tank and its out of the cabins summer temp.

 

[LS1FJ40]

This sounds really cool.