I was just looking at that one on Amazon...but it's Halotron 1...I wasn't sure it would be able to snuff out the types of engine fires we've been seeing...

 

Apparently what comes out of the rear end of the global population of cows is one of the biggest global pollutants- maybe our steaks are doomed!

There are some legislative things that make real sense but plenty that do not.

When I was 17 at a forum for potential chemical engineers in my home city university, I debated the most pre-eminent British chemical engineer [then retired] about the potential damage of atmospheric pollutants from burning hydrocarbons. I argued about the amount of CO2 and NOX being pumped into the atmosphere and blowing towards Scandinavia from all European countries was bound to cause damage due to the amounts of acids being dropped supposedly at molecular level.

This most distinguished and highly honoured gentleman, duly dismissed my arguments stating that such had been taken into consideration and was simply not a problem. About 10 years later they discovered acid rain in Scandanavia was denuding their forests!

The trouble with top experts is that they are all too often allowed to get away with murder when quite often in reality they do not know what they are talking about. How many experts told us that smoking was safe? Thank goodness I called that one right and have never smoked a *** but then we learnt of the potential damage caused by secondary smoke inhalation- urrgh!

The same logic that told me acid rain was dangerous also tells me that Halon is just not a significant problem when looked at in totality compared to all the other crap being thrown up in the atmosphere. On industrial gas turbines most enclosures to my knowledge are still protected by Halon despite political pressure to get rid because there is no comparable system performance wise. But folks should not forget they only discharge when something goes pear shaped and if the halon was not there and the bloody thing burned to the ground [as they easily do] then that probably releases more harm than the limited dose of halon.

I did not see any Greenpeace flags flying from the Saturn 5's and Space Shuttles.

928 owners should be exempt- the rest can walk!

Rgds

Fred

 

At times I've needed to employ the "art defense" that it's a thing of beauty I have running 50% leaded gas.

Still... My daily drivers are all in top tune and run efficiently and cleanly. It's the widespread and seemingly mundane things that really add up to cause environmental damage.

 

I was also looking at the Halotron alternatives. For the small (2.5lb) sizes the Halotron is maybe 20% less cost than real 1211. In most of the computer and electronics rooms I find myself locked in, The halon has bee removed (and recyled/sold) by clients wishing to maintain the image of environmental purity. It's also pretty hard to find the large quantities needed fast if there is a discharge.


Curt notes that jet engine test stands are usually equipped with water deluge systems. Steam turbines have the same, and they are used as much for quickly cooling metal parts as they are for smothering a flame. Like a car exhaust only moreso, oil (lubricating or hydraulic) will self-ignite when it comes in contact with combustion-heated metal parts. In the case of the steam turbines, the shells regularly reach 1000º F+ in service. In either case, oil tends to be relatively high-pressure, so any tiny leak makes a nice combustible fog.

On the gas turbines, the areas where fuel is introduced are closed compartments with generously-sized CO2 bottles for deluge.

In all of these, there are electronic IR flame detectors. In the case of the deluge systems on the turbines, those are dry headers with thermo heads, in concert with IR detectors operating pilot dump valves. Woe to the welding tech or mechanic who forgets to disable the flame detectors, then strikes an arc in the area monitored by the IR systems. In fuel compartments there are also gas leak detectors if the engine is natural-gas fired.

The IR flame scanners would be an interesting addition to the engine bay. I think I'd want to run it in alarm-only mode for a while before connecting to a Halon or Halotron auto-dump system.

 

What sort of air temperature do our cars reach under the hood?

Seems vw campers have a habit of going up in flames and some owners are fitting automatic systems that go off if the engine bay hits 79c.

This for example

http://thelatebay.com/index.php?threads/vw-aircooled-works-fireboy-fire-suppression-system-group-buy.23248/

Also seems common for boat engine rooms. 79c seems the standard.

 

Halotron 1 should work as well as Halon 1211 as long as its discharge rate is approx 2x - e.g. the nozzle aperture will need to be bigger - however that means your extinguisher will also last ~half as long when discharging. That will likely still be OK - but I'd much rather have it last long as possible - and 2x is a big difference.

Alan

 

Again - even with Halon if you discharge on the highway at speed - all the halon will be behind you very fast - it just doesn't make any sense.

Halon works by displacing Oxygen and starving the fire - if you have a huge feed of fresh air entering the engine bay at the front then it can't do that... Even the described chemical would be flushed very fast and it's unlikely it would stall the engine due to the location of the CAI's, a VW camper has much less airflow at the back for sure but I'm still skeptical how well that would work... if gas is spraying out from a leak there is a lot of very hot stuff around - especially if the engine is still running...

Alan

 

Ok I get your point about motorway speed but a fire could happen at any time. Wasn't there a post recently where the guys car went up in his garage. I think the conclusion was a build up of fumes which then ignited when he started the car. Plus I'm sure I read that this stuff requires a very low concentration to be effective. Just wondering if it would be practical to have something that is automatically triggered at 79 c under the bonnet. I guess the only way to know would be to measure the temps in a suitable area.

 

I'm trying to tell you it is simply not practical. Price out a Halon 1211 extinguisher - then tell me if you want something else to decide when to "blow it all" OR if you want to decide for yourself?

It really isn't a hard decision - think it through...

I worry not one bit about my car sitting in the garage - either before I start it or after I shut it down.

Before & after I start from cold the risk is really very low, after I shut-down the risk diminishes extremely rapidly. In either case I'm right there when the risk is real...

In the garage I have access to 2 halon extinguishers, 3 dry powder extinguishers and a 10lb foam extinguisher. I think I'd be OK under any almost any scenario.

Alan

 

Mike,

You have the engine operating at around 90C, engine oil oil leaving the motor at around 120C and the exhaust headers at significantly higher temps in a small air space. The airflow across the radiators probably reaches 80C by the time it enters the engine bay so there is an awful lot of heat floating around that vicinity.

Once something catches fire, localised temps will rise rapidly to about 500C which is why other bits such as wiring and plastics rapidly combust. Fire detection systems are designed to recognise the heat signature of a flame and thus trigger a counter measure [Halon, water spray etc].

Thus if one was install an automatic system based on temperature it would have to have a set point significantly higher than 79C or most likely it would be going off every time the motor was fully warmed up I suspect.

Rgds

Fred

 

Most older VW vans have the distinction of popularity, and the other distinction of having the tank adjacent to and above the engine. The hoses and such between them are out of sight out of mind, and leaks tend to evaporate fairly quickly so there's little or no visual evidence of a problem if you do happen to pull the engine to look. Until the fuel starts hitting the hot exhaust and cylinders, when fire becomes inevitable. Guidance for those folks is the same as what's shared here: PM replacement of older hoses on a schedule, and don't rely on a visual inspection for clues that they are failing.

 

I once saw a guy pour a can of straight 50W oil along the barrel of a hot .50 cal. machine gun. It burst into flame as it touched the barrel. So hot headers and an oil leak are a recipe for flames beneath the hood.

 

Valid thought.

I'm certainly not a fire fighter and my advice could be terrible.

 

I see this issue as multi-faceted.

1) Assume you have a fire. How do you fight it?
2) Preventative maintenance so you never get to #1.

#1 has several known sources of fire, each of which may have different actions for #2, and different methods and best known methods to put them out.

PREVENTATIVE MEASURES...
Source: Botched maintenance on the fuel rails. This is what got me. to avoid this:
1) Always place the injectors on the rails one at a time, put on the clip, then install the rail on the intake.
2) Test fuel pressure by removing the right relays before firing up the car for real

Source: Failed fuel lines
1) Replace those. Today.

Source: Failed fuel pressure gauge
1) Install for tuning only, then remove.

Source: Cat fire
1) If it feels like you're driving on 4 cyl, STOP. Don't pull over on grass
2) Make sure your coils and wires are up to snuff and are in good condition

I'm sure there are other fail modes out there, as well as "BEST PRACTICES" for putting out the fires, which will probably start a flame war all by itself.

For the record, I used a particulate extinguisher because it was RIGHT THERE (not by accident, either), but had to finish off with my halon one that was mounted in front of the passenger seat. Fire started with the hood open, so I didn't have to deal with any of that scary stuff.

 

Good organization of thought here IMHO. To sources I would add:

Power steering hoses

Transmission cooler hoses (AT cars)