Fire protection systems

[Mother]

I am considering adding a Fire Protection System to my engine bay. Any sugestions on a type, or any down side to pulling the safety pin and using the on board system. I already have the required small hand held extinguisher.

[vref120]

You could set up like an aircraft extinguishing system. Need a fire loop and a squib bottle. They are fairly easy systems. Fire loop once heated to a certain temperature, creates an electrical contact and provides the visual cue (in a 737 this is a light and a bell), and arms the squib. A separate button or handle fires the bottle. A squib bottle for a smaller turbine would be your best bet, but after you discharge it, run away.

[mrmustang]

Originally Posted by Mother

I am considering adding a Fire Protection System to my engine bay. Any sugestions on a type, or any down side to pulling the safety pin and using the on board system. I already have the required small hand held extinguisher.

Forget about gas based systems in a Cobra, go with a AFF (liquid based) system. Non corrosive and easy to clean up should you need to discharge.



Bill S.

[J.Jensen]

The AFFF (if you missed an F) film/foam liquid extinguishing media is HIGHLY corrosive - don't let anyone tell you anything else.

The positive side is - foam can be quickly washed away, unlike powder media which gets in everywhere and eats up your whole wiring...

For gas based systems you can choose between CO2 and Ingergen. Halon is off the market unless you know someone "on the inside" in the aircraft industry that will give you an old bottle.
The gas required to extinguish isn´t that high if the gas can be contained, but in an engine bay a lot will bleed out. Which means you need an obnoxious amount of gas. That rules out CO2 - because of the low pressure in the bottle (1000psi vs Inergens 4500). But we´re talking a lot of space and a lot of weight.

In an aircraft - the nozzles are spread out in the entire engine compartment and the pipe diameter is quite large to let as much gas into the compartment in as short time as possible.

The problem with gas systems is they may very well put out the fire - but it does so by removing the oxygen. Its still hot enough to burn, so it will relight when the O2 levels increase again. An AFFF foam system will cool as well as take away the O2 - plus it doesn't bleed out and become ineffective. Once the foam is in the engine bay - nothing will catch fire again.
I haven´t seen anyone make a system for installation with nozzles fixed under the hood though. There are plenty of hand held AFFF systems out there - but if the thing catches fire a dry powder ABC handheld, preferably 55A classified, will be a HELL of a lot more effective than the AFFF option.

JJ (Aircraft Maintenance tech and workplace firefighter).

[J.Jensen]

Doubleposted..

[dallas_]

I have an ESS (Emergency Supression Systems) foam system.

They say it's non corrosive. Maybe it is, maybe it isn't.

But fire is quite a bit more corrosive, so if I ever have to use it I expect the potential corrosive effect of the foam won't be at the top of my worry list at the time.

[Mother]

All sugestions are greatly appreciated. I understand that fiberglass burns very hot. In the event an engine room fire, I would like to save as much as possible. I feel that a Fire Supression System is the best system because the foam puts the fire out. Cleaning off the foam and maybe the lines that supply the foam is better idea. A great deal more damage will occure if the little bottles of ABC we all carry is not enough to put the fire out.

[mrmustang]

Originally Posted by J.Jensen

The AFFF (if you missed an F) film/foam liquid extinguishing media is HIGHLY corrosive - don't let anyone tell you anything else.

Sorry to disagree as your statement is too broad, and too vague in nature. Modern day, automotive based and offered Coldfire systems are NON CORROSIVE and NON TOXIC in nature. Having had one shoot off in my face several years ago (damn customers two year old actually knew to pull the pin and push on the actuator. Thankfully, it was his car and not mine ), I can tell you from very personal experience that they are non corrosive. Of course there are industrial versions, and poor quality, not well thought out other automotive AFFF systems that may be, but the automotive ones personally used (I prefer ColdFire) are most certainly not.

Bill S.

[J.Jensen]

AFFF is a PFC based foam agent, ColdFire is a water wetter - you cannot compare the two.

There are other foam agents available, alcohol resistant foams, protein based foams, even PFC-free foams have become available on the market - but these are not AFFF foams.

I´m not saying a foam based system is not good - its very very good at what its made for. I would use it too if my car cought fire.
But the fact is still that the AFFF contains flours that are not good for you and very corrosive.

[Mother]

Thanks guys for the info. I only wish to ensure a fire (if it happens) is put out.