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benkampot 08-14-2008 09:03 PM

Perlite Sand Help Please!!
 
Hi
I have been unable to locate perlite in cambodia but have come across perlite sand. It is Labeled 26-50 mesh. Does anybody know what this is or how to use it.
Or is it possible to place a cermanic fiber -luyangwool rated to 1260 degress f- between the hearth slab and firebrick or would this create an uneven cooking floor, or maybe put some tiles between the insulation and firebrick base.
or third option is to place the insulation under the hearth slab. i realize you would be heating the whole slab but would it still be ok or two much termal mass.
:confused: Benkampot

SpringJim 08-15-2008 03:37 AM

Re: Perlite Sand Help Please!!
 
Is that perlite sand light material? My finished Perlite cement product floated like styrofoam.

Maybe perlite sand is an unrefined product??

Can you find a foam board insulation for under the hearth....the wool will get compressed somewhat ....little strength and you lose insulating value

benkampot 08-15-2008 04:07 AM

Re: Perlite Sand Help Please!!
 
Hi springJim,
Thanks For your comments. (s) (m)

(s)Is that perlite sand light material? My finished Perlite cement product floated like styrofoam.

(m)The perlite sand is quite heavy, it is very fine and 20kgs is only about a cubic foot in volume.


(s)Can you find a foam board insulation for under the hearth....the wool will get compressed somewhat ....little strength and you lose insulating value

(m)So far unable to find insulation boards in cambodia or vietnam. Was concerned that crushing the ceramic woven blanket would reduce insulation properties i was thinking about possibly pouring a layer of rebar concrete then using some two inch lenghts of vertical rebar through the blanket and supporting another 1in layer of concrete and the firebrick paste and bricks on top of this. I have no idea if this is structurally sound idea or not. I guess i would be increasing the thermal mass and some heat would pass through the rebar but best thing i can think of.
Thanks again for you response
Ben

Wiley 08-15-2008 08:48 AM

Re: Perlite Sand Help Please!!
 
I suspect SpringJim is correct and that this product is the material the expanded perlite we are used to using comes from. See link.

Regarding the insulation question.... have you checked into insulating refractory bricks? If you are not familiar with them they are the same size as firebricks but unlike firebricks their purpose is to insulate against heat transfer rather than permit it. If you will be using regualr firebricks in your construction perhaps the same seller would have them.

Wiley

INDUPLEX, INC.

benkampot 08-30-2008 12:37 AM

Re: Perlite Sand Help Please!!
 
Hi,
Thanks alot for the advice. After another trip to vietnam i have been able to locate some insulating firebricks. However i was not able to buy the ideal amount. I have read on the site that it is recommended that you place two layers of the brick on their wide side down or one layer on the long narrow side for the insulation, each brick is 9"x 4 1/2" x 2 1/2". I think somelse talks about three inches.
I have planned on building an oven with an internal diamater of 100cm, about 39", and to have the oven dome outside the cooking floor. I estimated that i would need at least 75 of these bricks for this oven to provide insulation for both the cooking floor and the bottom of the dome. However i was only able to get 60 of these bricks. So i was wondering if anybody knew the best plan of attack.
I was thinking either using all the bricks two form two layers under the cooking floor and leave no insulation where the dome meets the hearth. Would i lose alot of heat this way?
A second option was to fan the bricks out over the full diameter of the cooking floor and dome. fanning out the bricks so that gaps are left but using two layers so that the gaps would be overlayed and fill the holes with sand. Thus creating a continous 5"layer of insulating brick for most but a 2 1/2" layer of insulating brick and a 2 1/2" layer of sand on the rest.
A third option is two try to cut the bricks and form a 3 3/4 inch layer over the whole area, or just go with a layer of single brick at 2 1/2 inches, as the bricks look as if they may crumble when trying to cut them.
Any further advice would be appricated. Thanks a million
ben


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