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rbigante 10-22-2008 06:19 AM

Fire Brick
I found a local fire brick supplier for $1.05/brick. Composition is as follows:
66.9% SiO2, 25.6% Al2O3, 2.5% Fe2O3, 2.6% alkali, 1.5% TiO2, etc. Recommended max operating temp is 2000 deg F.

Does this look like the right stuff? I assuming SiO2 is silica of some sort and Al2O3 is Alumina of some sort but I really didn't pay too much attention in chemistry (it was an 8:00 am class)

egalecki 10-22-2008 07:48 AM

Re: Fire Brick
I don't recall firebrick composition being in any of my chem. classes... so I think you're ok. ;)

How much does one brick weigh? I think a medium/low duty brick of the standard size should weigh about 9 pounds. Insulating firebrick, which you don't want, are lighter, and the high-duty ones, which are REALLY hard to cut, are heavier.

I think the weight is in the plans from FB.

rbigante 10-22-2008 08:03 AM

Re: Fire Brick
Thanks for the reply Elizabeth. The composition from the FB plans were 30% alumina and 50% silica. I believe weight should be approx 8 pounds. I know, 100% these are not insulating fire brick...way too heavy. The mfg rates them as 'low duty' but its the chemical composition I'm concerned with.

If my assumptions are correct, are the differences in percentages (between FB plans and mfg product data literaure) a big deal? Therefore the silica content would be approximately 15% more and the alumina content approximately 4% low.

also, i just spoke with a chemical engineer. he indicated that my assujptions are correct.

RTflorida 10-22-2008 08:24 AM

Re: Fire Brick
In my research (almost 2 yrs ago), I found "low duty" to be from 24% to 35% alumina, depending on the manufacturer. None of my findings came from a chemical engineer (I don't think you need one), all was based on data sheets and the info provided from several brick yards and a refractory supplier.
That said, I chose "low duty" fireplace bricks that were 77 cents a piece, weighing around 8.4 to 8.5 lbs. I believe they are rated to 2100 degrees and have an alumina content of 26.5%........No cracks, no spalling, heats up quick, no issues at should be fine with you choice.


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