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Author Topic: How is your fire system?  (Read 4067 times)
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Dr Goggles
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« on: January 12, 2010, 12:44:03 AM »

This I first posted on our build diary but thought it might be a good idea to start a new thread ...

Now , here is something that some people might find interesting.....

Yesterday the Colonel and I emptied the smaller bottles we had for our fire system .You may remember me commenting that they were failing at an alarming rate, one failed inspection before we went to the lake last year, another one ruptured not long after we got back from the lake and a month or so back we found the pressure lost in yet another one.

When we emptied them we found there to be large chunks of solid , some of them the size of your fingernail, one of the dip tubes broke ,and they were all blocked anyway......To be honest I'd bet my last dollar they wouldn't have worked, the solids would have blocked the nozzles....if they got that far..........And by the way....it's just soap, whatever they want to call it.

Due to the fail rate I made the comment to the Rev and the Colonel that we may as well empty the cylinders  after each trip to the lake because the solution corrodes the cylinders so badly, the checks and refills are much cheaper than the hardware , so in the long run it will work out cheaper ( and have more peace of mind ) to empty and clean them every year and then have them refilled the month before we go.We have also decided to leave the mounting of the bottles until we arrive at the lake to alleviate the risks of vibration to the cylinders themselves from their mounts which seems to be where they let go first.

I'm glad our car didn't catch fire............................................................... 

So, tell us about your system, or whether you've fired one off in anger.....

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http://thespiritofsunshine.blogspot.com/

Current Australian E/GL record holder at 215.041mph

THE LUCKIEST MAN IN SLOW BUSINESS.
Dr Goggles
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« Reply #1 on: January 12, 2010, 06:06:25 PM »

 This morning I spoke to our local agent who has been very helpful in the past with our fire system. To say he was dismayed at the news would be an understatement. The bottles are filled with nitrogen and he said as he has in the past that he has never been happy with the aluminium bottles and has been trying to source stainless steel bottles.As he stated if the compound corroded the aluminium cylinders it should never have been approved.

He runs a large commercial fire system installation business but for years raced sprint cars so he has an intrinsic interest in the specific field of race car extinguisher systems , he was not the least bit dismissive and extremely concerned. I committed to sending him the corroded parts to inspect and forward to ColdFire.
 
He was also extremely surprised to hear that there were solids in the bottles , particularly the amount and size of pieces that I told him about.
Dr G.
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Few understand what I'm trying to do but they vastly outnumber those who understand why...................

http://thespiritofsunshine.blogspot.com/

Current Australian E/GL record holder at 215.041mph

THE LUCKIEST MAN IN SLOW BUSINESS.
Dr Goggles
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« Reply #2 on: January 12, 2010, 06:08:49 PM »

 I just thought that there may be a chance that there has been some reaction between the nitrogen and the contents casuing Nitric acid to be formed?.......any ideas peoples?
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Few understand what I'm trying to do but they vastly outnumber those who understand why...................

http://thespiritofsunshine.blogspot.com/

Current Australian E/GL record holder at 215.041mph

THE LUCKIEST MAN IN SLOW BUSINESS.
Geo
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« Reply #3 on: January 12, 2010, 09:29:31 PM »

Yes, some foams tend toward acid.  Some info from the other post to keep it all on this thread.  A little research on foam leads me to not want use aluminum bottles (even with corrosion inhibitors).  Perhaps there was no corrosion inhibitor included in your mix.  Still stainless steel is better although steel looks OK.  Some info and links for the rest of you.  I pulled a few lines from documents to illustrate the confusion.  It will take further research on my part to decide what type of extinguisher to add to the one I already have.

From the ColdFire site. But rebutted in further documents.

Unlike old-fashioned AFFF foam, Cold Fire is completely non-corrosive and has an indefinite shelf life. You can put it in a 1.5 or 2.5 gallon extinguisher, or in the water tank of your crash truck and forget about it. It will never gel, crystalize, separate or corrode the metal. RDR offers even smaller 2,3 and 4 liter fire extinguishers with fixed nozzles. It can even be used in closed loop suppression/sprinkler systems.

http://www.fire-end.com/foam_types.htm

Fire fighting foams can be put into two very broad categories: Class A, and Class B. These categories correspond to the types of fuels that the foams are designed to be used on. This is very important! No matter what any salesman tells you Class A foam is not designed to put out class B fires. It looks white and bubbly, but they are chemically not compatible. Using Class A foam on flammable liquids (Class B) could extinguish the fire but lead to catastrophic results because of its inability to secure the explosive vapors. Class B fuels can be subdivided into two more subclasses: Hydrocarbons like gasoline, kerosene, and fuel oil will not mix with water; and polar solvents like alcohols, ketones, and ethers which will mix with water.

Class B foams can be divided into two general categories: synthetic based or protein based. Both types have advantages and disadvantages.

Synthetic foams are basically super soap with fire performance additives. They include high expansion foam, aqueous film forming foam (AFFF), and Alcohol Resistant aqueous film forming foam (AR-AFFF). In general synthetic foams flow more freely and provide quick knockdown with limited post fire security.

Protein foams use natural protein foamers instead of a synthetic soap, and similar fire performance components are added. Protein type foams include regular protein foam (P), fluoroprotein foam (FP), alcohol resistant fluoroprotein foam (AR-FP), film forming fluoroprotein (FFFP), and alcohol resistant film forming fluoroprotein (FFFP). In general, protein based foams spread slightly slower than synthetic, but produce a more heat resistant, longer lasting foam blanket.

http://www.firehouse.com/forums/showthread.php?t=35275

Protein-based foams can offer a significant advantage over detergent-based foams, however. Under some conditions, detergent foams make certain fuels easier to ignite.

Aqueous film forming foams (AFFF) are water-based and contain corrosive chemicals.
Suitable for use with carbon steel, fiberglass, polyethylene or stainless steel.
It is intended for use at a proportioning rate of 1% (1 part AFFF concentrate to 99 parts water) on Class B hydrocarbon type fuels such as gasoline, kerosene, diesel, etc. Chemguard 1% AFFF is not intended for use on fuels, which are polar solvent/water miscible such as alcohols, ketones, esters, etc.
Full stainless steel cylinder that resists corrosion.

Protein foams include regular protein foam (P), fluoroprotein foam (FP), alcohol resistant fluoroprotein foam (AR-FP), film forming fluoroprotein (FFFP), and alcohol-resistant film forming fluoroprotein (AR-FFFP).
FFFP foam on blended gasoline is your best choice because gasoline blended with MTBE prevents AFFF from forming a film under the bubbles.

http://safetyinfo.wordpress.com/fire-safety/classification-of-fire-extinguishers/water-foam-fire-extinguishers/

Geo
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Dr Goggles
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« Reply #4 on: August 17, 2010, 10:42:53 PM »

just thought I'd bump this topic as a member asked me a question about our fire system.......

We got a "cold-fire" system, very little of the original system remains. The kit came with aluminium lines, these are easy to shape and install, they are equally easy to damage, likewise they came with pretty anodized fittings, these are easy to use and just as easy to damage. Last year I replaced everything with bundy tube and brass line nuts. All four of the original 1.5kg cylinders we got ruptured. Not violently but just got pinholed and lost pressure. Aluminium is impervious to almost everything...but it doesn't like alkalis and detergents which continually dissolve the protective oxide layer that keep everything else out......Coldfire is an AFFF ( aqueous film forming foam...or something like that) which is basically soap.It is a bi-polar solvent meaning it can dissolve in polar solvents like fuels and also in ionic solvents such as water, the detergent properties allow them to mix...however AFFF's function is even simpler, it forms a film around the fuel which prevents it getting oxygen.AFFF does not contain or liberate any noxious liquids or gases...that's why we chose it.

On the negative side AFFF has some storage problems , it eats Aluminium bottles and it coagulates. What this meant apart from the bottle problems we had was that when we opened up the bottles that had failed we found that the AFFF had formed large lumps at the bottom of the bottle and also blocked the dip-tube........they wouldn't have worked anyway....simple pressure testing and weighing does not detect this problem.We have decided to minimise the issue by emptying the bottles every year , I decant the AFFF into a large black plastic(lightproof) drum which can be agitated to keep it mixed and then get Wormald to refill and recharge the bottles which costs about $35 a pop.

AFFF is the best because it won't kill or maim you. CO2 or Halon systems are the best extinguishants but they don't protect against re-ignition...for example in the event of a fuel spill and an elecrical short causing sparking the fire will continually reignite if the only extinguishant is CO2 or a halon because it doesn't contaminate the fuel.Co2 and halon systems are dangerous for living things, there is no argument.

None of these systems are perfect , no fire follows rules.

Minimise the amount of fuel you carry. Maximise the protection of your fuel system components and engineer fail-safes into the system , particularly if you have electric fuel pumps.

Pay special attention to potential flow paths of loose fuel within the vehicle. Picture this scenario, if you were sitting in the drivers seat suited up with the engine running at full noise and I tipped what would be equivalent to 3/4's of your fuel load into the car near your fuel tank, and lit it, what would happen? Could it flow to where you are? Will it burn or disable your parachute?

We tend in the rush to get the bare essentials when it comes to fire systems, expect the worst and you won't be disappointed when things get little hot in the car.

I'm going to post what I've written above.

My suggestion would be to buy either new or second hand bottles ideally they would be steel.......use bundy or copper tube rather than al and put more than they require in.Have lots of drain holes.
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Few understand what I'm trying to do but they vastly outnumber those who understand why...................

http://thespiritofsunshine.blogspot.com/

Current Australian E/GL record holder at 215.041mph

THE LUCKIEST MAN IN SLOW BUSINESS.
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