Dan C Tarro on thu 19 mar 98
I am in the later stages of ordering firebrick for our new car kiln and
may have made a mistake. I would appreciate any input that any one would
have who has used 2600 deg. bricks in their kilns. I have order these
bricks to be used inside and out for simplicity sake. I am now wondering
if the heat loss will be too great and should be placing 2300's on the
outside layer. The kiln will be around 75cubic feet firing at cone 10 in
reduction, gas, 9" walls may be placed within a wood structure building
with 9' ceilings.
I have currently logged off Clay Art temporary to get some work done, so
if you respond, please respond directly to my E-Mail address.
Oaktreestoneware1@juno.com
Thank you,
Dan Tarro
Oak Tree Stoneware
Ham Lake, Minnesota
_____________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com
Or call Juno at (800) 654-JUNO [654-5866]
Talbott on fri 20 mar 98
On our approx 50 cubic ft. gas car kiln we used 2300's on the
outside layer and 2600's on the inside. We typically fire to cone 10 in
heavy reduction with no problem. However if I had to do it again I would
have used the 2600's through out as the two different rated bricks are just
slightly different in their physical dimensions.. Marshall
>----------------------------Original message----------------------------
>I am in the later stages of ordering firebrick for our new car kiln and
>may have made a mistake. I would appreciate any input that any one would
>have who has used 2600 deg. bricks in their kilns. I have order these
>bricks to be used inside and out for simplicity sake. I am now wondering
>if the heat loss will be too great and should be placing 2300's on the
>outside layer. The kiln will be around 75cubic feet firing at cone 10 in
>reduction, gas, 9" walls may be placed within a wood structure building
>with 9' ceilings.
>
>I have currently logged off Clay Art temporary to get some work done, so
>if you respond, please respond directly to my E-Mail address.
>Oaktreestoneware1@juno.com
>
>Thank you,
>Dan Tarro
>Oak Tree Stoneware
>Ham Lake, Minnesota
>
>_____________________________________________________________________
>You don't need to buy Internet access to use free Internet e-mail.
>Get completely free e-mail from Juno at http://www.juno.com
>Or call Juno at (800) 654-JUNO [654-5866]
http://www.PotteryInfo.com
101 CLAYART MUGS (Summer 1998)
2ND ANNUAL CLAYARTERS' GALLERY - NAPLES, MAINE (Summer 1998)
E-MAIL ME FOR APPLICATIONS
Celia & Marshall Talbott, Pottery By Celia, Route 114, P O Box 4116,
Naples, Maine 04055-4116,(207)693-6100 voice and fax,(call first)
---------------------------------------------------------------------
John Baymore on sun 22 mar 98
------------------
Dan,
Thought I'd put my 2 cents in here.
(clip)
I would appreciate any input that any one would have who has used 2600 deg.
bricks in their kilns. I have order these bricks to be used inside and out
for simplicity sake. I am now wondering if the heat loss will be too great
and should be placing 2300's on the
outside layer. The kiln will be around 75cubic feet firing at cone 10 in
reduction, gas, 9=22 walls may be placed within a wood structure building
with 9' ceilings.
(snip)
2600 rated IFB is rated for continious duty to that tmperature in typical
industrial settings. It is a good choice for the lining of a potters kiln
for cone 10 use that you want to last for a long, long time.
IFB has two main factors that you want to consider in selecting grading for
wall construction. One is the maximum continious use temperature, and the
other is heat transmission per inch of thickness.
Generally the higher the temperature use rating, the lower the resistance
to heat flow (worse insulator). This is basically because the higher the
use rating, the more actual clay there is in the brick.....ie less little
insulating air spaces. That's why they are heavier per brick than the
lower duty bricks ..... at least one reason anyway.... composition being
another.
So a 2600 IFB can withstand more heat, but it passes more heat through
itself. So a wall of solid 9 inches of 2600 brick will stand up to higher
temperature better than a solid wall of 2300 brick, but it will =22lose=22 =
more
heat to the outside cold face surface. Poor economy. particularly when you
are paying MORE for the bricks and they insulate worse that you want. A
solid wall of 2300 will insulate better, but it will not stand up on the
hot face as well as the 2600. So poorer longevity and higher repair costs
as the hot face starts spalling and slagging over time.
So the 2600 is a good hot face brick in this application. To get better
insulation properties out of the wall section, you want to switch to a
higher insulation value brick behind the hot face brick, called the backup
layer. When you insulate the cold face of the hot face brick (called the
interface point) you contain the heat being lost through the hot face
brick. How well you do this determines the interface temperature that will
occur. You want the backup brick to be rated to a use temperature that
will not be exceeded at the interface layer.
There is some math to do this interface and heat transmission calculation
for any complexity of layers and layers of stuff. Having done a lot of
these calculations, I have found that with 2600 IFB on the hot face of a
cone 10 kiln, that 2000 IFB provides the best overall total wall insulation
value as a backup layer if both are set strecher course at 4 1/2 inches
thick (headers of 2600 every 6th course). The interface temperature in
this configuration is not over 2000 F in typical firing conditions, so
there is plenty of margin for the 2000 IFB on the backup layer. And the
2000 IFB has significantly better resistance to heat flow than the 2300 IFB
you are talking about. So.... a long lasting efficient wall section.
A better insulating 9 inch wall can be built with more complex layering of
brick grades, but for most potters kilns, this is overkill. The ideal wall
would have continiuosly decreasing maximum use temperature and continiously
increasing resistance to heat flow=21 It don't really exist except in =
theory
=3Cg=3E.
If you were to vary the original 26/20 IFB design idea, and decided to put
some backup insulation behind the layer of 4 1/2 inches of 2000 brick which
is behind the 4 1/2 inches of 2600, then you COULD cause the interface
temperature to jump over 2000F, thereby overfiring the hot face of the
backup 2000 IFB. The extra insulation layer traps heat escaping the cold
face of the 2000 IFB, and that raises the interface temperature, although
it increases the overall insulation value of the overall wall. For a short
time, the extra insulation would decrease heat loss to the cold face of the
wall. Then the hot face of the backup 2000 IFB would begin to deteriorate
over time and damage would occur. That would reduce the insulating value
of the 20000 IFB and start to negate the heat loss savings of the extra
insulation. It also would start physical deterioration of the wall
structure. Bad=21
BTW..... I use Greenlite 28's for firebox construction in places mostly
reserved for traditional hard brick use. Good frame abrasion and
reduction/corrosive resistance with a higher insulating value. Only use
hardbrick on the actual working floor.
And don't underinsulate the floor=21 Heat transfer knows no direction =
except
from areas of higher concentration to areas of lower concentration..
Yes, the bricks are slightly different sizes. Learn to set brick and that
is no real problem. Experience is a good teacher here. Use fireclay
mortar to level, or commercial bonding mortar. Level a little over many
courses, not all in one. Particularly check the level in all dimensions of
the header courses. If you use commercial mortar, you'll have to allow
expansion joints..... the structure becomes monolithic... all glued
together. No expansion joints and you get severe wall cracking. Have a
good masons level, and some string levels.
A little troweling, tapping, and fiddling and it all goes together fine.
The better insulated the kiln wall is the lower the cold face temperatures.
That means that the exterior of the kiln will remain a bit cooler during
the up cycle. It will not be as strong a radiant source of heat to the
surrounding room walls. So better in a wooden frame structure, as far as
radiant heat goes (watch out for dead air spaces collecting heat from
convective transfer over time).
Far more concern in this =22fire hazard=22 regard is the radiant heat =
escaping
from the burner ports. Possibly consider sealed port or cage mount
burners, if you have solid knowledge of kiln design stuff like that and how
it might affect the overall design of the unit. At the end of firings seal
the burner ports to cut radiation ( and extend retention nozzle and
thermocouple, flame rod, or ultraviolet detector life).
Ecologically, the better insulated the kiln the less fossil fuel consumed
from the planets' finite resources, and the less CO2 being dumped into the
atmosphere. Good stuff to think of too.
Hope these thoughts are of help with your project. Good luck.
Best,
..................john
PS: BTW.... you are not the Taro Dan from Mashiko, Japan are you?
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA
603-654-2752
JBaymore=40Compuserve.com
Grimmer on wed 25 mar 98
John,
That was a thorough and informative article on kiln wall insulation
and I enjoyed reading it. Your thoughts on the matter match
everything reliable I have come across except on one point.
I responded to Dan's question off-list by saying that 2600s don't
transmit huge amounts of heat, just somewhat more than 2300s--
they shouldn't be a problem. To make sure I wasn't mistaken, I
checked the APGreen IFB test data sheet. Lo to my surprise, they list
the G26 as having _better_ insulating properties than the G23! The
primary difference between the two seems to be the Al:Si ratio
rather than density. Their figures:
G23
Al2O3 39.5%
SiO2 54.5%
Fe2O3 1.5
CaO 1.2
MgO 0.3
TiO2 2.0
KNaO 1.3
Bulk Density 40 lb/ft^3
Mod. Rupture: 325 psi
Thermal Conductivity@2000F: 3.0 Btu-in/ft^2
G26
Al2O3 56.5%
SiO2 38.1%
Fe2O3 1.0
CaO 1.3
MgO 0.3
TiO2 1.3
KNaO 1.5
Bulk Density 40 lb/ft^3
Mod. Rupture: 200 psi
Thermal Conductivity@2000F: 2.6 Btu-in/ft^2
Perhaps this is a case where industry went and changed the rules
on us while we weren't looking, or it is a case unique to APG bricks.
Do you or anyone out there have info on other manufacturer's IFB?
steve grimmer
marion illinois
DIANA PANCIOLI, ASSOC. PROF. on thu 26 mar 98
Do I remember that it is 2000 degree brick that insulates better? I used
2000 degree brick for back up. They are a different
material--diatomaceous earth, rather than kaolin/sawdust construction.
Do you have a chart for them?
Diana EMU
On Wed, 25 Mar 1998, Grimmer wrote:
> ----------------------------Original message----------------------------
> John,
> That was a thorough and informative article on kiln wall insulation
> and I enjoyed reading it. Your thoughts on the matter match
> everything reliable I have come across except on one point.
> I responded to Dan's question off-list by saying that 2600s don't
> transmit huge amounts of heat, just somewhat more than 2300s--
> they shouldn't be a problem. To make sure I wasn't mistaken, I
> checked the APGreen IFB test data sheet. Lo to my surprise, they list
> the G26 as having _better_ insulating properties than the G23! The
> primary difference between the two seems to be the Al:Si ratio
> rather than density. Their figures:
> G23
> Al2O3 39.5%
> SiO2 54.5%
> Fe2O3 1.5
> CaO 1.2
> MgO 0.3
> TiO2 2.0
> KNaO 1.3
> Bulk Density 40 lb/ft^3
> Mod. Rupture: 325 psi
> Thermal Conductivity@2000F: 3.0 Btu-in/ft^2
>
> G26
> Al2O3 56.5%
> SiO2 38.1%
> Fe2O3 1.0
> CaO 1.3
> MgO 0.3
> TiO2 1.3
> KNaO 1.5
> Bulk Density 40 lb/ft^3
> Mod. Rupture: 200 psi
> Thermal Conductivity@2000F: 2.6 Btu-in/ft^2
>
> Perhaps this is a case where industry went and changed the rules
> on us while we weren't looking, or it is a case unique to APG bricks.
> Do you or anyone out there have info on other manufacturer's IFB?
>
> steve grimmer
> marion illinois
>
Grimmer on thu 26 mar 98
Diana,
Here's the figures for APG G20. I don't think they're made of
diatoms or a sawdust mixture; too much room for variation that way.
The bricks I have purchased from APG look to be made from a slip
pushed through tiney little holes, a la garlic presses. The spagetti
is then formed into brick and fired. Some manufacturers form the
material into big slabs, fire, and cut to size. This apparently makes
for a more uniformly-sized brick. Anyway:
G20 LI (Low Iron)
Al2O3 40.0%
SiO2 56.5%
Fe2O3 0.7
CaO 0.4
MgO 0.1
TiO2 1.6
KNaO .7
Bulk Density 45 lb/ft^3
Modulus of rupture: 110 psy
Thermal Conductivity@1600F: 2.2 Btu-in/hr-ft^2
No figure given for 2000F
The number for the G23 at this temp is 2.7
The numbers for Empire High Duty Fire Brick:
@1600F: 9.2
@2400F: 9.8
Does all this mean that the differences in heat transfer between
different grades of IFB are not really worth bothering over? ie build
your kiln with G26 if you can afford them, otherwise line with 26s
and back up with a cheap IFB. Or just build with 23's and be
prepared to line it eventually and maybe rebuild?
steve grimmer
marion illinois
DIANA PANCIOLI, ASSOC. PROF. wrote:
>
> Do I remember that it is 2000 degree brick that insulates better? I used
> 2000 degree brick for back up. They are a different
> material--diatomaceous earth, rather than kaolin/sawdust construction.
>
> Do you have a chart for them?
>
> Diana EMU
>
> On Wed, 25 Mar 1998, Grimmer wrote:
>
> > ----------------------------Original message----------------------------
> > John,
> > That was a thorough and informative article on kiln wall insulation
> > and I enjoyed reading it. Your thoughts on the matter match
> > everything reliable I have come across except on one point.
> > I responded to Dan's question off-list by saying that 2600s don't
> > transmit huge amounts of heat, just somewhat more than 2300s--
> > they shouldn't be a problem. To make sure I wasn't mistaken, I
> > checked the APGreen IFB test data sheet. Lo to my surprise, they list
> > the G26 as having _better_ insulating properties than the G23! The
> > primary difference between the two seems to be the Al:Si ratio
> > rather than density. Their figures:
> > G23
> > Al2O3 39.5%
> > SiO2 54.5%
> > Fe2O3 1.5
> > CaO 1.2
> > MgO 0.3
> > TiO2 2.0
> > KNaO 1.3
> > Bulk Density 40 lb/ft^3
> > Mod. Rupture: 325 psi
> > Thermal Conductivity@2000F: 3.0 Btu-in/ft^2
> >
> > G26
> > Al2O3 56.5%
> > SiO2 38.1%
> > Fe2O3 1.0
> > CaO 1.3
> > MgO 0.3
> > TiO2 1.3
> > KNaO 1.5
> > Bulk Density 40 lb/ft^3
> > Mod. Rupture: 200 psi
> > Thermal Conductivity@2000F: 2.6 Btu-in/ft^2
> >
> > Perhaps this is a case where industry went and changed the rules
> > on us while we weren't looking, or it is a case unique to APG bricks.
> > Do you or anyone out there have info on other manufacturer's IFB?
> >
> > steve grimmer
> > marion illinois
> >
| |
|
