Automatic Fire Supression

[ThreePointFive]

As I get closer to the end of the build, I'm conscious of how many potential fire hazards there are in a Land Rover. I wondered if anyone has experience with fire suppression equipment in any vehicle, what works and what doesn't.

Ideally, anything fitted would be automatic so there's no reaction time/decision making involved and would work whether the car is on or not. Initially I was looking for the kind of systems where a pressurised container is linked to a pipe that melts at the point of fire and releases the extinguishant. There are downsides to this, mostly storge and packaging.

I came across these and it looks like they tick off many of my wants - they're always active, take up minimal room and don't need a human to act. My biggest concerns are behind the dash where I have miles of DIY wiring that might decide to short and in the engine bay, where the hazards are slightly more obvious. One of these run along behind the dash would be easy enough to route and there is no easy external access to that area in a hurry. I would secure another to the bonnet so as to fit around the plenum/over the fuel rail area when closed.

I will have a handheld 2kg powder extinguisher in the cabin but don't want to rely on that.

Does anyone have any thoughts/experience on the subject?

[Arjan]

IF fused correctly, wiring should not cause a fire.  For a dash to get to 120 C. and that tube to respond, you will have a serious issue anyway. However, if it makes you feel more at easy, why not.

Often, some smell & smoke will inform you of a serious problem before the fire starts and this tube would work.

A good cut off switch makes less mess and is IMHO more effective. Fuel can cause problems, obviously. Good, as in tested, certified etc., automatic systems will cost more than the vehicle due to liability etc. And a few fire extinguishers are never ever a bad idea - as long as you train and know how to use them..

 

[FridgeFreezer]

I'd consider it way over the top and more likely to fail/go off prematurely than actually save you. Vehicle fires are quite rare and, as said above, wiring fires should be very unlikely indeed if you're designed the system properly.

If the wiring catches fire it's already gone - slightly-melted wiring is as trashed as fully burnt wiring. The Defender's weak spot is the unfused main feed from engine bay to dash (easily fused) and the battery in the seatbox & starter wiring.

Also these things look rather bulky & inflexible, I don't fancy your chances wrestling one of them in behind the dash and out through the bulkhead grommet in any sort of tidy fashion - and if it rubs against something on route presumably it goes off randomly as you're driving down the road.

Quote

Tube Dimension 18mm(D)

Working Temperature -30ºC~80ºC

Operation Temperature 80ºC or 120ºC ±10ºC

I've only had to put out one (vehicle) fire, that was a TD5 with an ECU full of water, and if he'd had to wait until the engine bay reached 120C there'd have been a lot more work needed than just a new ECU.

I'd carry a decent fire extinguisher or two and call it done.

[miketomcat]

I actually spoke to the rep for the firefighter 2m. It looks like a great idea and very simple to fit. It is basically a low melt point plastic tube filled with pressurised fire suppressant. They were designed specifically for race car application but they are now looking at marine application's (hence my conversation). I think if you feel you have a need then it's a great solution.

Mike

[ThreePointFive]

All,

thanks, I know this appears to be overcautious but I know that most vehicle fires are caused by wiring and this is my first go at wiring an entire vehicle - the mess behind the dash is truly frightening.

I have fused everything except the battery to starter feed, but there's always potential for a mistake to have been made. This would be insurance against any mistake on my part, but I take on board what you say about the heat needed to activate the extinguisher being too high to save the truck.

Fridge - it would be one behind the dash and another in the engine bay, you are right that it would never get through the grommit!

I'll keep an open mind, if the space exists and isn't being used for anything else then it loses me nothing.

[Snagger]

Those extinguisher systems are aimed at fuel and hydraulic fires, not electrical - as Arjan said, an isolator switch to cut the battery off is more effective - an electrical fire stops as soon as you kill the power and cools relatively quickly as the wires conduct heat nearly as well as electricity, as do the metal structures the wiring may have shorted on.

It would take an enormous electrical fire to trigger one of those extinguishers.  By the time it did, the car would already be a writeoff.  The biggest threat from dash fires is not the fire itself (small and easily extinguished), but the extraordinary amount of smoke the insulation produces.  It’s toxic, but worse, it’s so thick that it’s blinding in seconds.  I had such a burn out in the dash (an un-fused wire contacted the exhaust and then burned back to the live side of the fuse box). It was the fact that I was reversing when it happened, so at low speed, that made the difference.  I was quick to shut off the ignition and the battery isolator (less than five seconds for both to be off from first seeing the smoke), but it still filled the entire 109 with dense smoke.  But I was lucky to be able to stop instantly and open the door.

That taught me that battery isolators are essential, so you can quickly disable the entire system, and that ventilation is critical to being able to maintain visibility and thus control.  That’s one of the reasons I fitted Defender doors with wind down windows and a pop up sun roof.  More importantly, make sure the wiring is in good order, well insulated and supported so it can’t chafe, have terminals drop off or contact hot surfaces.  Prevention is the key, not extinguishers!

 

 

[Arjan]

Although a fuse in the startermotor feed is possible, is is not practical.

IF you're worried - please fit the that system and I hope it will never bee needed.

We have an extra insulation on that feed (gardenhose - don't tell the Mrs....) with a cut off switch

The rest is fused..

I understand that our wiring is not standard - nor are the vehicles.. - but fuses are easy to fit.

 

 

[miketomcat]

The single biggest thing to remember is. A fire extinguisher is purely designed to give you enough time to get out and put the fire out. It is NOT designed to save the vehicle. If it does you just happen to be lucky.

Mike

[Tanuki]

Worth looking at the AFFF extinguishers used for rally-cars; a nozzle in the engine-bay and a couple behind the dash, with an external release-pull [you don't want to be in the vehicle when the extinguisher goes-off!]

There was another system I saw used some time back which involved a small-diameter - about 1/4-inch - thinwall green plastic pipe that was threaded through all fire-likely locations and back to the gas-bottle. Get a fire and the pipe melts, dumping the bottle-contents. Probably no longer available outside the aerospace/military/nuclear/medical industries though, because it used BCF gas.

[FridgeFreezer]

@Arjan I'm slightly concerned that all of your fuses appear to be 20A rating

Also, garden hose isn't bad (any extra sleeving/protection can't hurt) I keep old radiator / heater hose for the same purpose, very tough - although hydraulic hoses are super tough with the internal steel braid, hard to flex/route though.

[Snagger]

I used 13mm plastic water pipe from a DIY store to use as sheathing for my battery cables where they pass the narrow gap between chassis and bulkhead foot wells - it’s s a snug fit for the cable, but it fits and is pretty tough and insulating.  Other vulnerable cables, fused or not, get convolute or slotted plastic sleeving, and are all clipped or tied in routes that protect them from disconnection or damage.  Like is said, prevention is better than dealing with the results of shorts, and spending a little time and money on fuse boxes, decent terminals, solder, heat shrink and conduit is much cheaper than losing the car or risking your well being!  
 

I was lucky with that burned wire happening at low speed in a yard, where I could stop immediately, but it scared the carp out of me!

[Ozzy50]

One thing I will input to this thread , dry powder extinguishers make a hell of a mess , they probably do as much damage as the wiring fire itself , yes they are ultra effective at putting the fire out but the powder stick to everything! I put out an under dash fire in my previous maxxum (tractor, the ignition switch shorted out , common fault apparently) and the resultant mess wrote the tractor off ! 

[FridgeFreezer]

Also worth noting that some extinguishers like CO2 will put the fire out... for a brief moment until the CO2 drifts away. Ask me how I know.

[ThreePointFive]

All,

thanks for the continued advice/comments etc.

 

Tanuki - those are exactly the systems I as thinking of, I have a mate who owns a historic rally car (run to latest MSUK regs) that was the inspiration for this, but the tanks are bulky in a 90.

 

For note, I have used anti-abrasion sleeving from WVP for pretty much everything, and for the stuff that will sit on top of the engine or near exhausts, some heat resistant sleeving. I have used heater pipe for some extra protection already, which has the added benefit of looking like it belongs there.

I've kept everything secured with cable ties (so many cable ties) everywhere/anywhere there is opportunity. My logic is that if it can't move, it can't abrade but of course I am sure it's possible to do that in such a way as to make it worse by pulling things tight onto sources of abrasion. I've tried to be careful.

I have a key-operated cut off that has a 100 amp continuous rating and a 500 amp 5-second rating that everything is coming through. I should only get anywhere near that if I had every eletronic on the car on at the same time as cranking, which I won't, and it barely cranks for a second before firing.

Having dealt with a vehicle fire in a professional capacity (1980's Civic burning up as the owner looked on), I'm under no illusion what can be acheived with anything that doesn't have DENNIS written on the front. In my view, an opportunity to save the vehicle is a bonus so a fit-and-forget solution sounded good. I might mock up something the same size as the FF tube thing an just see how it sits but I'm no longer sure it's the right tool for the job in the cabin. Still thinking about it for the engine bay, though. Knowing of the legendary corrosiveness of the powder was another reason those tubes sounded preferable.

 

 

[landroversforever]

My thoughts are how much of a wiring issue you'd have before it got hot enough to melt the tube for that kind. What about the ones which you can discharge manually? 

[Carloz]

First thing: Take a foam (instead of the cheap powder) extingisher. 

Powder type maybe(!!) safes the car from fire but eats the car in its own way..

[landroversforever]

Foam not good for electrical though if I remember correctly? Or needed to be a specific rating? It's been a while since I did my fire training at work!

[Blanco]

48 minutes ago, landroversforever said:

It's been a while since I did my fire training at work!

Me too, but I remember powder being very difficult to use successfully, it was CO2 for electrics, AFFF foam for pretty well everything.

Problem is if you have that much heat going on under the bonnet or wherever then pretty soon it becomes a flammable liquids issue, so the foam might actually be the thing? 

I actually keep a couple of old Halon ones, you can't buy them anymore but they are unbeatable for vehicle fires.

[ThreePointFive]

Thanks to advertising practices that I am sure in no way infringe on our privacy, Youtube showed me the FF2 system as an ad so I've now seen how it works. Definitely not going to cut it for the dash area, anything worth saving is gone well before the thing would activate - just as everyone said. I am, however, more convinced for the engine bay than I was - any chance of fighting it without opening the bonnet and introducing yet more air is a winner.

AFFF is not intended for electrical fires so even that is no good for this situation. So decision made - I have everything fused, protected from abrasion as well as I can and on a cut off switch, and can't benefit from these systems.

 

[FridgeFreezer]

AFFF may not be rated for electrical as most electrical fires would be 240v or higher and you don't want a conductive liquid anywhere near that, just like you don't want your toaster in the bath with you... but 12v electrics are unlikely to cause an issue, we don't get electrocuted or have our trucks burst into flames when we go wading.

[Ozzy50]

I have to ask , would it put a diesel or oil fire out in the same manner , I have my doubts. 

[Nonimouse]

I deal with the clean up from hundreds of vehicle fires, working closely with Trumpton.  Biggest cause of vehicle fires is a minor electrical fire melting into the brake or clutch fluid reservoir/pipe. This is almost imposible to put out until you completely deny it oxygen....

 

[Snagger]

I remember watching a TV programme talking about car crashes and it showed that almost all resultant fires are caused by the hydraulics rupturing and spraying the brake/clutch fluid onto the exhaust system.  They ran en engine up to moderate temperatures and sprayed diesel, oil and petrol onto the exhaust manifold, and not much happened other than boiling off.  Then they sprayed some brake fluid and it was quite spectacular.

[missingsid]

On 1/3/2021 at 10:43 AM, Blanco said:

Me too, but I remember powder being very difficult to use successfully, it was CO2 for electrics, AFFF foam for pretty well everything.

Problem is if you have that much heat going on under the bonnet or wherever then pretty soon it becomes a flammable liquids issue, so the foam might actually be the thing? 

I actually keep a couple of old Halon ones, you can't buy them anymore but they are unbeatable for vehicle fires.

I also have an old work Halon in the S1, BUT the use of them is illegal, not sure of the ownership of them.

Any Halon is going to be well out of date.