#21  
Old 09-18-2009, 10:42 PM
Il Pizzaiolo
 
Join Date: Jan 2007
Location: Tampa, FL
Posts: 1,446
Default Re: FB insulating blanket alternatives?

The blanket is at least twice as efficient as perlcrete or vermicrete. I used both, as many do. 1 layer of 1" blanket and 3 inches of perlcrete is sufficient. If using perlcrete alone, as LEAST 4", preferably 5-6".
Personally, I had already purchased 3 bags of vermiculite and 3 bags of perlite and intended to skip the blanket.....then I found a fantastic deal on ebay for a 25 sq. ft roll of 2" #8 Insulfrax blanket, so I proceeded with 1 layer of the 2" blanket and 2 1/2" of perlcrete. I've been totally happy with heat ups as well as retained heating.

RT
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  #22  
Old 09-18-2009, 11:55 PM
kebwi's Avatar
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Join Date: Aug 2009
Location: Seattle, WA, USA
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Default Re: FB insulating blanket alternatives?

So, ceramic fiber blanket seems to be pretty standardized. One parameter is the density in pounds for cubic foot, which is usually four, six, or eight. I believe FB's is eight. What are the performance differences between the three? Why would you want four, six, or eight for a particular application? As far as I can tell, they all have the same max temperature tolerance. Do the different densities offer varying thermal insulation for the same overall blanket thickness? If so, are the less dense or more dense blankets more insulative, i.e., better for brick ovens?
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  #23  
Old 09-19-2009, 06:03 PM
david s's Avatar
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Location: Townsville, Nth Queensland,Australia
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Default Re: FB insulating blanket alternatives?

QUOTE=Yahoo-Archive;267]The rule of thumb is 1" blanket and 4" vermiculite. I had an insulation engineer run a test, and conclude that the blanket replaces 2" of loose vermiculite. We had them run a simulation where they added 1" of insulfrax, and reduced 1" of vermiculite. 1":4", 2":3", etc. over a 24 hour 1000F exposure. The outer face tested consistently dropped by adding 1" more insulfrax and 1" less vermiculite.



1" Insulfrax Blanket 6#, 4" Vermiculite 1000F** 172F

2" Insulfrax Blanket 6#, 3" Vermiculite 1000F** 161F

3" Insulfrax Blanket 6#, 2" Vermiculite 1000F** 151F

4" Insulfrax Blanket 6#, 1" Vermiculite 1000F** 142F

5" Insulfrax Blanket 6# ******* 1000F** 135F


Test shows loose vermiculite 50% the efficiency of blanket. Cement added to vermiculite, not shown in test, will further reduce the efficiency so use as little as possible.
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  #24  
Old 09-19-2009, 06:28 PM
Journeyman
 
Join Date: May 2009
Location: Detroit
Posts: 398
Default Re: FB insulating blanket alternatives?

Just to add a bit of info I didn't see in this thread(sorry if I missed it).

I recently finished my oven and have now fired it twice post curing. I used 6 inches of loose fill insulation around the entire oven and have yet to measure a temperature above ambient on the outside even with the oven at 1000F. The obvious downside of this method is the foot of space it takes around the oven.
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  #25  
Old 09-22-2009, 08:50 PM
philiph4@ameritech.net's Avatar
Peasant
 
Join Date: Aug 2009
Location: Farmington Hills, MI
Posts: 26
Default Re: FB insulating blanket alternatives?

I have 1" kao wool blanket. It should be enough foe a 2 inch layer. Is this enough insulation?
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