Plastic doghouse covers and fire oh my....

[Air345Fly]

The ceramic blanket materiel is not really suitable for use where
there is vibration. It feels soft and pliable, more than fiberglass,
but the ceramic fibers are very brittle. The hardening compounds
like waterglass make it hard but do nothing about it's brittle nature.
The ceramic blanket will work great for a short time.

You would be far better off using insulating blankets intended
for automotive applications.

[PeterH-350LE]

Originally Posted by Portage to Caravan

I retired from the oil-chemical industry where I was employed to install Kaowool on piping and within furnaces, and I couldn't more highly advise against using it. If you breath any dust off of it the coughing fit that will ensue will make you wonder if you'll ever draw another clear breath. It is absolutely brutal, and silica has been found (or accused) of causing lung cancer. You need to take special precautions when using it.
There are other options available. Talk to someone at your auto suppy house about fire resistant fabric.

Jim

Originally Posted by Air345Fly

The ceramic blanket materiel is not really suitable for use where
there is vibration. It feels soft and pliable, more than fiberglass,
but the ceramic fibers are very brittle. The hardening compounds
like waterglass make it hard but do nothing about it's brittle nature.
The ceramic blanket will work great for a short time.

You would be far better off using insulating blankets intended
for automotive applications.

Thank you both for your input based on real life experience, priceless!!
I cancelled my order of the ceramic blanket material and the Colloidal Silica Rigidizer.
The search will continue. Any input about an automotive type fire resistant material is appreciated.

[Andrew T]

When the classics were new they had 1” thick pad glued to the bottom of the doghouse cover. It had a sheet of lead built into in and a heavy foil cover. This was there for sound reduction and fire suppression.
We used to buy it from Airstream on occasion for other projects. It was very expensive as I remember.

[PeterH-350LE]

Originally Posted by Andrew T

When the classics were new they had 1” thick pad glued to the bottom of the doghouse cover. It had a sheet of lead built into in and a heavy foil cover. This was there for sound reduction and fire suppression.
We used to buy it from Airstream on occasion for other projects. It was very expensive as I remember.

Thanks for the input, Andrew. I am almost certain my doghouse cover is original. I will check it out and see what the components are. My biggest problem is that the pad you describe lost adhesion and several attempts to reglue it have failed. The foamy material just continues to fall apart. I never looked for a sheet of lead, but have wondered why it does not break apart.

[bkahler]

Originally Posted by PeterH-350LE

Thanks for the input, Andrew. I am almost certain my doghouse cover is original. I will check it out and see what the components are. My biggest problem is that the pad you describe lost adhesion and several attempts to reglue it have failed. The foamy material just continues to fall apart. I never looked for a sheet of lead, but have wondered why it does not break apart.

It must have been a very thin sheet of lead or else previous owners disposed of it. Neither my 310 or the 345 had any sort of lead sheet. There remnants of the 1" pad still in place.

I think the cover itself is made from the same material as the gray and black water tanks, at least that's what it looks like to me. I'm almost certain it's not ABS.

My concern in a fire is even with a fire blanket protecting the bulk of cover, the edges where it sits in the rubber seal around the doghouse opening is going to be susceptible to the heat and could possibly (likely?) allow the doghouse cover to sag and fall on top of the engine which would leave the opening pretty much fully exposed. All fire needs is a small gap to get started.

This brings me back full circle to possibly try and fabricate a steel replacement cover. I looked at the cover again briefly last night and the more I look at the more I think I can make a steel replacement.

[PeterH-350LE]

Originally Posted by bkahler

It must have been a very thin sheet of lead or else previous owners disposed of it. Neither my 310 or the 345 had any sort of lead sheet. There remnants of the 1" pad still in place.

I think the cover itself is made from the same material as the gray and black water tanks, at least that's what it looks like to me. I'm almost certain it's not ABS.

My concern in a fire is even with a fire blanket protecting the bulk of cover, the edges where it sits in the rubber seal around the doghouse opening is going to be susceptible to the heat and could possibly (likely?) allow the doghouse cover to sag and fall on top of the engine which would leave the opening pretty much fully exposed. All fire needs is a small gap to get started.

This brings me back full circle to possibly try and fabricate a steel replacement cover. I looked at the cover again briefly last night and the more I look at the more I think I can make a steel replacement.

Even with a steel cover, you will need some gasket for it to rest on, just for a good seal both for heat and sound.

[bkahler]

Originally Posted by PeterH-350LE

Even with a steel cover, you will need some gasket for it to rest on, just for a good seal both for heat and sound.

Yes, but once the rubber doghouse cover seal melts the metal doghouse cover will just settle down onto the metal frame. It would take a fair amount of heat over a sustained period for the metal to sag enough to be a problem. I think kidjedi's pictures show that the steel cover did it's job and didn't collapse. He talks about the number of fire extinguishers it took as well as spray from a garden hose. The fact that the cover remained intact is what impressed me the most.

[bkahler]

The real problem as I see it when switching to a metal cover vs the plastic cover is the weight difference. The Argosy steel covers were all hinged with prop rods so you just lifted the lid and set the prop rod in place.

The plastic covers are light enough you just lifted them off and set them aside while working on the engine. A steel lift off cover is going to be a fair amount heavier and when you add in the weight of a heat blanket and carpeting on top it might be to unwieldy for one person to lift and relocate for service work.

Decisions decisions......

[bkahler]

I've been doing some rough (VERY rough) calculations to try and determine what the weight of a steel cover might be.

For the moment I would lean towards 16 gauge steel (0.625" thick) mainly because the cheap English Wheels are limited to around that size. 16 gauge steel weighs about 2.156 pounds per square foot.

For rough size numbers I'm using 3' wide and 4' long as the opening size. I know for certain that those dimensions are on the high side, probably by a fair amount. I'm also assuming 12" high on three sides which is excessive because of the taper from rear to front.



3' x 4' = 12 sq/ft for top
1' x 11' = 11 sq/ft for sides
23 sq/ft x 2.156 lbs = 49.6 lbs total steel weight

Worst case is the steel weight would be just under 50 lbs. I'm guessing 35 lbs is probably a more realistic number.

So the question is, is 50 lbs too heavy for a doghouse cover to be easily handled from inside the cab?

Currently my plastic doghouse cover is bare, no coverings or insulation. I'll have to weigh it to get a baseline weight.

One other thought came to mind recently. Would a diesel rig be less prone to an engine fire?

Brad

[Air345Fly]

If you have an engine fire your only hope is to put it out fast.
With a plastic cover you have less time to get it out.
With a metal cover you have somewhat longer.

If your worry is a fire you would do much better with an
automatic extinguisher system then worrying about the
difference between metal or plastic engine covers.

[bkahler]

Originally Posted by Air345Fly

If you have an engine fire your only hope is to put it out fast.
With a plastic cover you have less time to get it out.
With a metal cover you have somewhat longer.

If your worry is a fire you would do much better with an
automatic extinguisher system then worrying about the
difference between metal or plastic engine covers.

As stated above I'm not concerned with the automatic fire extinguishing system in this discussion. This discussion is about what to do about the plastic cover. I think it's pretty well established that plastic will melt faster than steel. The question is what can we do about. Yes, an extinguishing system will help, that should be obvious to anyone. As you mentioned earlier the products I had brought up previously are not a good match for this application. That's the sort of information I'm looking for.

I believe kidjedi's fire is a good indicator that we have a better chance of surviving physically and keeping our coaches from burning to the ground if we have some sort of metal cover.

Martin's suggestion of remolding the covers out of some sort of fireproof product is a great idea. Unfortunately the odds of getting something like that done are probably pretty slim. However I have an idea on that subject and I plan on pursuing it just in case it pans out.

[PeterH-350LE]

no lead in this insulation, I was able to push the blade all the way through

[martin300662]

What about something like this?

https://www.techflex.com/high-temperature/silver-foil

[PeterH-350LE]

Originally Posted by martin300662

What about something like this?

https://www.techflex.com/high-temperature/silver-foil

Nice and affordable. 1200 degrees F !!Thanks for finding that. Summit is selling 36"x60" Mats, perfect size for the doghouse.

https://www.summitracing.com/parts/tcx-tza36-0sv60

[Portage to Caravan]

I so wish this program had a like button.
I like the solution you've come up with here, and I love the way everyone here shares their experience and assistance even coming up with a workable solution. Thanks for sharing this with us. I'll bet this will come in handy for some more insulating- isolating uses.

Jim

[LM782]

I'll weigh my doghouse (after the Tropical Storm blows by) and report back. As is it's not heavy, but it's not light either.

I had a close call when some wires shorted that a previous owner ran to the dashboard simply by squeezing them through an opening at the upper left corner of the doghouse. If our coach had a gas leak at the carburetor things would not have turned out so well. Scary moment (scarier to think about what could have happened).

Before adding something like the silver foil lining, I need to shore up what I have. I'm left wondering what the original construction is supposed to be and how it's held together.

My (plastic) 1985 doghouse has two layers of insulation. The layer closest to the engine is starting to fall apart from contact with the AC compressor. It's made up of a thick aluminum foil, fiberglass insulation and a crust of semi rigid plastic about 1/8" thick (which is beginning to break up). Above that is what looks to be some paper product, then another layer of fiberglass and then the plastic doghouse shell. I ordered some thick aluminum tape from McMaster to try to keep what I have together, but it likely needs some supporting structure.

Comparing my doghouse with Peter's, it seems mine has a metal (possibly copper) channel on the sides and base at the very edge helping hold the various layers together, which is then held in place by what appears to be blind rivets. I'm searching where to find a similar channel. I'm thinking about adding some at the edge that tucks into the dashboard which currently doesn't have any to hold up the drooping fiberglass and aluminum foil. With everything held in place, there's room to add another layer to potentially help contain a fire.

Luis

[bkahler]

Originally Posted by PeterH-350LE

Nice and affordable. 1200 degrees F !!Thanks for finding that. Summit is selling 36"x60" Mats, perfect size for the doghouse.

https://www.summitracing.com/parts/tcx-tza36-0sv60

Here's a slightly cheaper source for Techflex 36 x 60 mat.

[PeterH-350LE]

Originally Posted by bkahler

Here's a slightly cheaper source for Techflex 36 x 60 mat.

...ships in 20 business days. I already have tracking from summit. I am way too old to be patient.

Dictionary
pa·tient

/ˈpāSHənt/
Learn to pronounce

adjective
adjective: patient

1. able to accept or tolerate delays, problems, or suffering without becoming annoyed or anxious.

[bkahler]

Originally Posted by PeterH-350LE

...ships in 20 business days. I already have tracking from summit. I am way too old to be patient.

Dictionary
pa·tient

/ˈpāSHənt/
Learn to pronounce

adjective
adjective: patient

1. able to accept or tolerate delays, problems, or suffering without becoming annoyed or anxious.

Yeah, that AIN'T either me

[PeterH-350LE]

27 pounds for my cover incl carpeting. I removed the insulation shell from the cover and the biggest problem I am having is the unstable material. It just flakes apart, which makes it hard to keep it glued down.
I am experiencing with sodium silicate to see if it will stabilize it and at the same time improve the fire rating. Problem would be that I would need at least 2 gallons, since its so porous.
Also I understand that the sodium silicate may harden and fire proof it, but make it more bridle on a different level. New grounds for me, just trying to explore options.