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## gas line size for kiln?

### Jon Anderson on tue 11 aug 98

What size line do I need to have in the ground to get the Btu's the kiln
needs. I would guess it is different for every kiln but lets say up to 75
cu.ft. soft brick kiln. How many BTUs would that be then?
Jon Anderson
Pottery and Blown Glass
Homepage: http://www.isd.net/jbander1/

### Marc Ward on wed 12 aug 98

Jon,

that you did not include with your post. They are;

type of gas
pressure of gas
length of pipeing run
number of elbows
what temperature you are firing to
how fast you want to fire

As you can see, there are many variables.

Marc Ward
Ward Burner Systems
PO Box 333
Dandridge, TN 37725
USA
423.397.2914 voice
423.397.1253 fax
wardburner@aol.com

### Earl Brunner on wed 12 aug 98

In a message dated 8/11/98 6:41:10 AM Pacific Daylight Time, jbander1@isd.net
writes:

<< --------------------------Original message----------------------------
What size line do I need to have in the ground to get the Btu's the kiln
needs. I would guess it is different for every kiln but lets say up to 75
cu.ft. soft brick kiln. How many BTUs would that be then? >>

Jon, You either missed the thread, or don't understand that there are SEVERAL
other important variables the someone would need to know in order to answer
that question.
Size of the kiln is only one of them. What is the btu ouput of your burners?
How many of them are there? If homemade kiln, do you have enough burners?
What temperature do you intend to fire to? Knowing that, you then need to
look at your gas delivery system. How many cubic feet of gas will your meter
deliver per hour? Will your gas company upgrade the meter if needed? How long
is the gas line run? how many turns in the pipe? Most of the good kiln books
will give you ways to figure out the diameter of pipe needed for the variables
in question, Olsens book or Rhodes, for example. Your gas company and/or a
certified plumber can help also. People here can help, but we need to have
enough information to be able to answer the question. Good Luck!

### Earl Brunner on wed 12 aug 98

In a message dated 8/11/98 6:41:10 AM Pacific Daylight Time, jbander1@isd.net
writes:

<< --------------------------Original message----------------------------
What size line do I need to have in the ground to get the Btu's the kiln
needs. I would guess it is different for every kiln but lets say up to 75
cu.ft. soft brick kiln. How many BTUs would that be then? >>

Sorry, I left off one thing, Your local building code may have a certain way
that they want the line installed. I had to install mine inside a larger
diameter plastic pipe(ABS) so that in the event of a gas leak I don't
satuarate the ground with natural gas and create an explosive situation. I
guess the theory is now that the leaking gas will come out either end of the
plastic pipe.

### Beth Wheeler on wed 12 aug 98

If you are talking about natural gas, then you also need to consider how
far the gas line is going to travel from the meter - this will determine
the pressure delivered to the burners too. The gas company has charts
which determine the size of line you need. My kiln needed a total of
1,000,000 BTU's, it is 40-50 feet from the meter, the water column
available from the gas co is 6(I think) and I needed to install a 2" gas
line to the kiln. My resourceful plumber suggested using the yellow
plastic (verythick) flexible gas line -which the gas companies use for
delivery systems in new construction - and that proved to be a wonderful
idea....wonderful because every turn (angle) for the pipe fittings you must
make decreases the available pressure. He used black pipe from the meter
to an underground trench where it is attached to the plastic pipe which
then curves to a point where it reconnects with the black pipe and goes up
straight to reach the fittings which eventually reduce the 2" gas line down
to the fittings for the burners.

Good luck!

At 09:20 AM 8/11/98 EDT, you wrote:
>----------------------------Original message----------------------------
>What size line do I need to have in the ground to get the Btu's the kiln
>needs. I would guess it is different for every kiln but lets say up to 75
>cu.ft. soft brick kiln. How many BTUs would that be then?
>Jon Anderson
>Pottery and Blown Glass
>Homepage: http://www.isd.net/jbander1/
>

### Fred Paget on fri 14 aug 98

Well I've finally finished building my gas kiln. It is an Oregon Flat Top
of 15 cubic feet,runs on natural gas and is supposed to fire to cone 10. I
have nine inch thick walls of insulating fire brick and two power burners.

The kiln is close to a 3/4 inch gas pipe line running to the greenhouse and
is about 110 feet from the meter with a dozen bends and direction changes.
I tried it with the 7 inch gas delivery pressure we now have and can just
make cone 01 before the kiln almost stalls. The rise in temperature is only
about 10 degrees per hour at that point. This is with an oxy-probe to check
the combustion. I get the maximum heat when the probe shows a neutral
atmosphere.

Because the pipe runs in a narrow area between the studio and the fence and
under several trees it would be very hard to dig for a new pipe. Gas pipes
have to be buried over 18 inches deep here. 1 1/2 inch pipe costs 40
dollars a 21 foot section at the local supply house. Well to make a long
story short I have decided to opt for a higher intermediate pressure from
the gas company. They have agreed to supply me with 1 pound pressure which
they will do for \$570 cash in advance. This pays for a new meter,
regulator, back-up regulator, and annual inspection in perpetuity. I also
had to buy two more regulators - one for the house and one for the
greenhouse. These cost about \$45 apiece and I had to install them myself.
Of course I had to get a permit which cost \$21.50 and do a pressure test.

Maybe I should have gone for a higher pressure of 3 pounds which was also
offered but since this is a small kiln and I will be getting 4 times the
pressure I have now I will have twice as much gas and that should be
enough. The higher the pressure the greater the danger from leaks and we
live in earthquake country here! (Had one this morning. 5.4 quake about 75
miles south of here on the fault line that runs about 4 miles west of here.)

From Fred Paget, in marvelous Marin County, California, USA

### Mike Gordon on sat 15 aug 98

Fred,
I'm surprised that no one told you that gas pressure isn't the main
factor in firing gass kilns - it's gas volume. P.G.&E will tell you that
you loose pressure the longer the distance is from the meter with all
those twists and turns. You need 1 1/2" or 2" line to fire that kiln to
c/10 How many btu's do the burners use? Call one of the local
colleges,kiln builders,or refractory guy's in your neighborhood they

### Fred Paget on sun 16 aug 98

Mike, Thanks for responding to my post.
I do indeed have a problem. The last thing I want to do is run big pipe.
The information I have indicates that the amount of gas delivered through a
pipe increases as the square root of the increased pressure. So if I have 4
times the pressure I now have I will get the square root of 4 namely 2
times the amount of gas at the kiln. Do you think that will be enough to
drive it up to cone 10 or should I try for 3psi which is 12 times the
present pressure and would give 3.4 times the quantity of gas I now have?
My two burner orifices are set for about 70000 BTU each but I will change
that as soon as I get more pressure. I think I will go up to 120000 each
for the first firing with increased pressure. I can get quite a bit more
out of the burners (I made them myself from designs in Nils Lous book and
advice from Dedell Gas Burner and Equipment Co.)
Because of the square root factor pressure is indeed not the main factor
but if you kick it up enough it should work. After all the gas company
delivers at 40 psi in the street with a small pipe in residential
neighborhoods, Regards, Fred

>Fred,
>I'm surprised that no one told you that gas pressure isn't the main
>factor in firing gas kilns - it's gas volume. P.G.&E will tell you that
>you lose pressure the longer the distance is from the meter with all
>those twists and turns. You need 1 1/2" or 2" line to fire that kiln to
>c/10 How many btu's do the burners use? Call one of the local
>colleges,kiln builders,or refractory guy's in your neighborhood they

From Fred Paget, in marvelous Marin County, California, USA

### Tracy Dotson on tue 1 sep 98

You will need aprox 10,000 BTU's per hour per cu feet if you use ins soft
brick so if you have a 75 cu foot kiln you will need 75,000 btu's delivered to
the kiln each hour. Devide this # by the # of burners and you will have how
much is needed for each burner. good luck Tracy

### Grimmer on wed 2 sep 98

Hi,
I would recommend a more conservative 16,000 Btu per cube. That works
out to 1.2 million Btu/hr. Better to have a bit too much power than a kiln
that won't reach temp in less than 24 hours, or not at all, right?

steve grimmer
marion illinois.
----------
>From: Tracy Dotson
>To: CLAYART@LSV.UKY.EDU
>Subject: Re: Gas line size for Kiln?
>Date: Tue, Sep 1, 1998, 9:21 AM
>

>----------------------------Original message----------------------------
>You will need aprox 10,000 BTU's per hour per cu feet if you use ins soft
>brick so if you have a 75 cu foot kiln you will need 75,000 btu's delivered
to
>the kiln each hour. Devide this # by the # of burners and you will have
how
>much is needed for each burner. good luck Tracy

### Vince Pitelka on wed 2 sep 98

At 10:21 AM 9/1/98 -0400, you wrote:
>----------------------------Original message----------------------------
>You will need aprox 10,000 BTU's per hour per cu feet if you use ins soft
>brick so if you have a 75 cu foot kiln you will need 75,000 btu's delivered to
>the kiln each hour. Devide this # by the # of burners and you will have how
>much is needed for each burner. good luck Tracy

Tracy -
Didn't you mean to say that they would need 750,000 BTUs per hour for a 75
cubic-foot IFB kiln? 75,000 BTUs would be for a 7 1/2 cubic-foot kiln.
- Vince

Vince Pitelka - vpitelka@DeKalb.net
Home 615/597-5376, work 615/597-6801, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166

### Tracy Dotson on sat 5 sep 98

It's nice that some one caught me on this. Actually I use Harry Dedell's
charts for BTU's for different kiln wall configuration. They have always
worked for me. His figure is 5,800 Btu/hr/cu.ft. for 9" 8 pfc inswool or 5" 8
pfc (inside) with 4" Block Ins 1800 deg. I always fudge this for a hard brick
floor and hard brick walls up to one row above the burner port. So it should
be aprox 44,600 btu for aprox 16 cu feet and 5,800 btu for 59 cu ft = 713,600
+ 330,600 = 1,044,200 Btu/hr/cu.ft....sounds a little better. Thanks Tracy
Hope I did not miss lead some potter some where.........

>You will need aprox 10,000 BTU's per hour per cu feet if you use ins soft
>brick so if you have a 75 cu foot kiln you will need 75,000 btu's delivered
to
>the kiln each hour. Devide this # by the # of burners and you will have how
>much is needed for each burner. good luck Tracy.......

Tracy -
Didn't you mean to say that they would need 750,000 BTUs per hour for a 75
cubic-foot IFB kiln? 75,000 BTUs would be for a 7 1/2 cubic-foot kiln.
- Vince

Vince Pitelka - vpitelka@DeKalb.net
Home 615/597-5376, work 615/597-6801, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166.......

Hi,
I would recommend a more conservative 16,000 Btu per cube. That works
out to 1.2 million Btu/hr. Better to have a bit too much power than a kiln
that won't reach temp in less than 24 hours, or not at all, right?

steve grimmer
marion illinois.

### Karl P. Platt on sun 6 sep 98

> 1,044,200 Btu/hr/cu.ft..

This is astronomical. My Pyrex melter, which runs well in excess of
2,900F requires only 1/4 of this heat release rate. I'd add that the
combustion hardware used was fabricated here as nothing readily
available could furnish enough flame in small enough a space. Read,
expensive.

KPP

### Tracy Dotson on mon 7 sep 98

I think I need to check my typing and maybe take more naps....

"So it should be aprox 44,600 btu for aprox 16 cu feet and 5,800 btu for 59 cu
ft = 713,600 + 330,600 = 1,044,200 Btu/hr/cu.ft....sounds a little better.
Thanks Tracy Hope I did not miss lead some potter some where".........

should have been 1,044,600 btu/hr/for a 75cu fiber kiln.......Maybe I an just
gitting old....Time for my 3 hr afternoon nap. Love ya Tracy