Safe Speed Forums

As a result of coverstaions with customers earlier to day I got to thinking..

"Should manual/automatic fire supression systems be fitted to new cars?"

You know, the sort of thing that race/rally drivers have as a matter of course!

Not only could this reduce the liklyhood of an unpleasent death it could also save a valuable car from total destruction.

(Eg from customers account of watching a 6 month old Saab going from a "Whisp of smoke under the bonnet" to "Burned out shell" in about 10 minits )

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"The road to a police state is paved with public safety legislation"

The competition systems cost hundreds of pounds, have to be checked and certified annually at the cost of £100+, and are primarily aimed at giving the occupants time to stop and get out of the car rather than saving the car from damage. If you've ever tried to put out an under-bonnet fire with a hand-held extinguisher you'll know how ineffective they are.

Bearing in mind how rare vehicle fires are, and how often things like this would be set of by the little tykes wondering what that bright red handle does, I think it's a non-starter. There's nothing stopping individuals from installing extinguishers if they like, but I don't think it's sensible to introduce them as a standard feature.

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Peter Humphries (and a green V8S)

True, re costs but.

Airbags were pretty expensive when they first came out (They still are if they have to be replaced)

Its all down to manufacturing volume. currently these systems sell "Thousands" per year Its pretty well a cottage industry.

If it was made mainstream the annual volume accross europe would be in the tens of millions.

"Misfires" would be a problem (But already we have "smart" airbag deployment systems that only deply the bags that are deemed nececarry)

It si just that, as a mechanic I am seeing more and more vehicles with electrical fires. Sure the fuse blows, but once the insulation has started to smoulder nothing can stop it unless you have a suitable extinguisher. Using said extinguisher takes a certain skill and presence of mind and involves a not insignificant risk! an automatic system may be better!

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"The road to a police state is paved with public safety legislation"

Lets look at problem from another angle - electric faults cause wiring to overheat,before fuse blows.Reducing fuse value not an option.
Problem - fuses take (on average) 2x current to blow, leaving wiring as you say getting hot.They need to be such that they will stand switch on surges -in this respect mcb are possibly better, but more expensive and bulkier.Other alternative would be an "electronic" fuse -
So instead of bailing out ship after hitting iceberg, we stop it hitting iceberg.

Only my 2D s worth.

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lets bring sanity back to speed limits.
Drivers are like donkeys -they respond best to a carrot, not a stick .Road safety experts are like Asses - best kept covered up ,or sat on

I am pretty sure that My Parents Mk4 Zephyr back in the late 60's early 70's had some sort of MCB based fuse board, I wonder why it didnt catch on?

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"The road to a police state is paved with public safety legislation"

Aeroplanes use MCBs - not fuses.

The trouble is the operator has to know what they are, what they're for, and what it means if it pops out.

Given that most cars just have an "Engine F*cked" light on the dashboard nowadays - leads me to believe that the bulk of the market would not accept a vehicle which required understanding.

Whilst I personally consider an oil pressure gauge, coolant temperature, cylinder head temperature, exhaust gas temperature and/or either manifold pressure/suction gauge as pretty much essential kit to know what's going on with the engine - most buyers thought this was clutter - hence you don't get it any more.

Some cars don't even have tachometers - let alone water temperature gauges


I severely doubt many car drivers even know what a blown fuse means. With MCBs they'd probably just glue it in if it started popping for any reason.

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Something stirring in back of memory about MCB used on DC supplies(something to do with the curve -but it's not my area of electrics) and the question of reliability of contacts when they got as small as they'd need to.
MCB was one sugestion to attempt to get a quicker cut off

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lets bring sanity back to speed limits.
Drivers are like donkeys -they respond best to a carrot, not a stick .Road safety experts are like Asses - best kept covered up ,or sat on

Cars are lumbered with 12 volt electrical systems so the current in many of the circuits is pretty high and can fluctuate quite a lot with battery voltage. I'm not sure MCBs lend themselves to this sort of environment. There is a big move amongs major manufacturers to go to 42 volt electrical systems to reduce current flow but everything (bulbs, radios, phone charges etc) are just geared to 12V.

Also, although fire extinguishers seem like a good idea, the number of car fires is pretty small. Strangely, whilst the motor industry is generally sinking in a sea of red tape, there are no requirements in the EC for fire retardancy as part of the type approval scheme!

It's surely all down to cost.
Years ago there was a flame inhibiting liner which could be fitted to the bonnet - never got off the ground.
You can have better wiring Brand Rex produce flame inhibiting cabling - but it's expensive.
I'm certain poor crimping causes problems - but it's expensive to solder so many connectors.
Computers could monitor current flows to indicate problems - but it's just too complex and costly.

The "problem" is too small to have any money thrown at it.

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Time to take responsibility for our actions.. and don't be afraid of speaking out!

Aircraft systems use PTFE insulated cables which don't burn easily (but are harder to strip) and if they are in critical areas will braid them in stainless steel (if I remember right) to prevent abrasive damage.

The technology has been available for year to prevent these sort of fires, but it is the usual "cost/benefit balance", the scandalous and most typically given example of which was the Ford Fuel Fires, where Ford had calculated that it was cheaper to have litigation for 180 deaths and 180 serious burn injuries, and 2100 burnt out vehicles, than it was to implement the safety changes, so it did nothing.

If "plumbed in" extinguishers were to be made mandatory it would be a complete waste of time and money; in fact it might even be a bad thing if it led to even the slightest degree of complacency about the potential problem of fires being addressed.

The bottom line is that since the Gov't restricted the materials that may be used for in-car fire systems they no longer work! Cars competing in motor sport can no longer use Halon systems, but must only be charged with aqueous foam (AFFF). If you've ever seen one of these go off then you'll realise just how ineffective they are - it's about the same as trying to put a fire out with a can of shaving foam!

In the old days when a rally car crashed and there was an underbonnet flash fire, there was a fair chance that an immediately deployed Halon system would put it out again. Now there's virtually no chance at all. The result is that such incidents regularly lead to completely destroyed cars; and it is only by good fortune that to date no-one has been trapped in one.

Whether TPTB have actually done any analysis on the relative environmental costs of (a) using Halon or (b) allowing complete cars to burn up on a regular basis seems unclear. Interestingly, aircraft are granted an exemption to the ban and can continue to use Halon systems that actually work; but the Government won't even consider a similar exemption for motorsport.

For road going cars I'd say we need to concentrate on prevention not cure. Improve the containment of flammable liquids under the bonnet (including brake fluid), and the mechanical / electrical protection of wiring, as mentioned earlier.

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CSCP Latin for beginners...
Ticketo ergo sum : I scam therefore I am!

I had to use one of these last year (3 liter hand held AFFF). I was expecting it to go off with a decent whoosh like those CO2 extinguishers do, but actually it was a very half-hearted affair. Luckily the fire was rather half-hearted too and the extinguisher was up to the job.

Edited to add:

Incidentally, I'm prejudiced against dry powder extinguishers because they have a reputation for leaving powder in every little nook and cranny, use one in any confined space (inside a car, for example) and you will have power blowing around for the rest of time. That's assuming the thing hasn't compacted and does actually work. However, the help chap at MK Fire who replaced the AFFF one was very strongly in favour of dry powder in terms of knocking the fire down. The only problem he saw was that it is impossible to see anything after you've triggered it. You have to have your back to the door as you trigger it and then walk out, because otherwise you'd never find the door. He said this was the single reason why they are never approved for use on passenger vehicles. If it wasn't for that slight problem, they'd be used virtually everywhere, or so he said.

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Peter Humphries (and a green V8S)

Formula 1 marshals have these. They make a mess but do the job.For the most part a car fire writes a car off IMHO. This is not to save the repair bill (it exacerbates it for reasons stated) but it is to put out the fire on safety grounds.

Is halon really dangerous to use under a car bonnet? I thought it was only when in confined areas?

Hmm 42 volts? Not 48? Why not 50 to make it a roundish number for once?!
I think I'd prefer a higher voltage like that in my car. Especially if it was some kind of standard low voltage with that ISO standard low voltage plug/socket available. Not that I've seen it, only heard of it's existance!

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Andrew.

Its 42 volts because that is 3 times 12 volts (On charge0

Means the battry manufacturers dont have to make "Special" battrys for the new vehicles as they are being introduced.

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"The road to a police state is paved with public safety legislation"

I know what you mean, but

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Peter Humphries (and a green V8S)

Make it 4 batteries and you get 48v-55v
Or do you mean these first generation cars would have 3 ordinary car batteries connected in series? That's a lot of weight!

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Andrew.

The increasing electrical loads in modern cars mean higher currents and the manufacturers wanted to raise the system voltage to handle higher powers like electric brakes and steering and save thmselves money on copper costs by using thinner wires. The reasons 42V was selected are basically:

- It is 3 x 14V (as noted above) and batteries would be easy to comec by.
- It is below the LVD limit for safety of DC circuits
- It is low enough that leakage would not be a problem.

After this was suggested, the makers of alternators and starters got cleverer and found ways of making their units more powerful at the 12V level thus rendering the expensive change pointless.

Also, all vehicles would have to be dual voltage (12V/36V) as most accessories are 12V supply (e.g. filament lamps at the higher voltage would be too fragile to have a long lifetime.)

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Malcolm W.
The views expressed in this post are personal opinions and do not represent the views of Safespeed.

Indeed they did!

Recently I worked on a Mercedes which had a Water cooled Alternator!

(Still means the poor thing is having to work at around 100C though! Guess thats why they only last a couple of thousand hours)

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"The road to a police state is paved with public safety legislation"

Its not 42V system,but 36V,ie 3 x12V We dont say our car has a 14V system,this is only the top of charge voltage.
So there it is we will have 36V system cars,this is an odd voltage,virtually nothing now made for 36V,24 V would have been better or for the brave 48V,now this is the new standard which I believe is being pushed for computer supplies,48v would rise to 56V just below the safe limit of 60.Of course any voltage of 24 or greater needs to be respected,put this in the hands of the diy no alls and there is serious danger!