David Woof on mon 26 jul 10
Hi James=3D2C
what is your source pipe size and source delivery pressure for the natural =
=3D
gas and how much gas volume available for conversion to BTU's do you expect=
=3D
to receive at the end of the 10' B'BQ hose typically used to deliver the m=
=3D
uch higher pressure and calories of propane? =3D20
=3D20
Or said this way: If one can easily "shut off" an open 3/4 inch pipe pushin=
=3D
g 6 pounds with one's thumb=3D2C how much actual natural gas will be pushed=
t=3D
hru a 3/8 hose? =3D20
=3D20
More than adequate hose is a blessing and a good place to start the learnin=
=3D
g process. Then you can grow those half inches Mel is talking about.
=3D20
Disclaimer: The foregoing is not offered as directions or advice. don't try=
=3D
this at home=3D3B asphyxiation=3D2C unconsciousness=3D2C explosion and dea=
th is =3D
likely to follow. Seek qualified=3D2C licensed assistance.=3D20
=3D20
Re. the gas company=3D3B I understand their avoiding your question because =
of=3D
liability issues. =3D20
Hire their tech and watch them come running. I know=3D2C I know!!! us clay=
f=3D
olks want to do it ourselves. Hopefully to learn and perhaps save money. Bu=
=3D
t giving each other advice re electricity and gas is getting ever more risk=
=3D
y!!! and we can't blame attorneys for the blame shifting litigiousness and =
=3D
growing evidence of stupidity.
=3D20
David Woof=3D20
________________________________________________________________________
9a. burner orifice size?
Posted by: "James Freeman" jamesfreemanstudio@GMAIL.COM=3D20
Date: Mon Jul 26=3D2C 2010 2:42 pm ((PDT))
=3D20
I just finished converting an old Jenken 1 1/2 cubic foot square
electric toploader to a raku kiln. I have a really nice home made
weed burner-type burner made by a machinist friend. He drilled the
orifice for propane. The hole must be a numbered drill size=3D2C which I
do not have=3D2C as a 1/16" bit fits the hole loosely=3D2C while the 5/64"
does not fit at all.
=3D20
I want to run the burner on natural gas through a 10' gas hose made
for barbecue grills. Can anyone venture a guess as to what diameter I
should drill out the orifice in the burner? As yet no reply from the
gas company. I think they are avoiding the question. I did fire up
the burner just to see what would happen=3D2C and I got a weak and lazy
flame=3D2C so the orifice is definitely undersized.
=3D20
Thanks.
=3D20
...James
=3D20
James Freeman
=3D20
=3D20
_________________________________________________________________
Hotmail is redefining busy with tools for the New Busy. Get more from your =
=3D
inbox.
http://www.windowslive.com/campaign/thenewbusy?ocid=3D3DPID28326::T:WLMTAGL=
:O=3D
N:WL:en-US:WM_HMP:042010_2=3D
James Freeman on mon 26 jul 10
I just finished converting an old Jenken 1 1/2 cubic foot square
electric toploader to a raku kiln. I have a really nice home made
weed burner-type burner made by a machinist friend. He drilled the
orifice for propane. The hole must be a numbered drill size, which I
do not have, as a 1/16" bit fits the hole loosely, while the 5/64"
does not fit at all.
I want to run the burner on natural gas through a 10' gas hose made
for barbecue grills. Can anyone venture a guess as to what diameter I
should drill out the orifice in the burner? As yet no reply from the
gas company. I think they are avoiding the question. I did fire up
the burner just to see what would happen, and I got a weak and lazy
flame, so the orifice is definitely undersized.
Thanks.
...James
James Freeman
"All I say is by way of discourse, and nothing by way of advice.=3DA0 I
should not speak so boldly if it were my due to be believed."
-Michel de Montaigne
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
jonathan byler on mon 26 jul 10
conversion is a little tricky, but not that hard. this probably needs
to be less exact than some would have you believe, but it is helpful
to be in the ballpark.
figure about how many BTUs of heat you need and then look on the chart:
http://www.joppaglass.com/burner/lowp_chrt.html
remember that doubling the ****AREA**** of the whole with all things
otherwise kept equal will roughly double the BTU output of the
burner. doubling the diameter does a lot more than double the area of
the whole, so you need to do a little geometry if you don't want to
follow the chart 100%. this guy:
http://www.wardburner.com/
will sell you a handy calculator/chart thing that will make it easier
to figure out orfice sizes and pressures and all the rest. good
fellow all around and very knowledgeable. I like to give him business
when I can because he has been so helpful to me in the past - even
regarding burners he sold us MANY years before I even started working
here. and his prices are pretty decent too. Mr. Ward once told me
the conversion factor for orifice size from natural gas to propane at
a given pressure, but I can't seem to find it.
the other option is do as mel said and just open it up slowly. I like
to have a screw in plug/spud that I can change out to different
sizes. the burners we have on our soda kiln have little pipe caps
that can be interchanged without much work. makes experimentation
easier and more fun.
On Jul 26, 2010, at 4:07 PM, James Freeman wrote:
> I just finished converting an old Jenken 1 1/2 cubic foot square
> electric toploader to a raku kiln. I have a really nice home made
> weed burner-type burner made by a machinist friend. He drilled the
> orifice for propane. The hole must be a numbered drill size, which I
> do not have, as a 1/16" bit fits the hole loosely, while the 5/64"
> does not fit at all.
>
> I want to run the burner on natural gas through a 10' gas hose made
> for barbecue grills. Can anyone venture a guess as to what diameter I
> should drill out the orifice in the burner? As yet no reply from the
> gas company. I think they are avoiding the question. I did fire up
> the burner just to see what would happen, and I got a weak and lazy
> flame, so the orifice is definitely undersized.
>
> Thanks.
>
> ...James
>
> James Freeman
>
> "All I say is by way of discourse, and nothing by way of advice. I
> should not speak so boldly if it were my due to be believed."
> -Michel de Montaigne
>
> http://www.jamesfreemanstudio.com
> http://www.flickr.com/photos/jamesfreemanstudio/
> http://www.jamesfreemanstudio.com/resources
douglas fur on tue 27 jul 10
James Freeman
Hnnn I would of said that the size you have was on the big side.
(I made a couple of burners to run off a propane tank from a bar-B-que-
whatever that pressure is- and 1/16" dia makes a gnarly roar and a tight
flame)
Could it be the burner? the dimensions of how far the orifice is from the
burner throat is critical on my burnrs it came out that having the otifice
.707 times the burner ID away from the throat was right. OK(second try at
English) this burner is a 7" long piece of 1" ID pipe with a 11/4" to 1"
bell. Set screws around the outer rim of the bell clamp onto a bushing at
the end of the 1/2" dia gas pipe. The bushing has a brass plug drilled wit=
h
a 1/6"dia orifice. the distance from the end of the plug to the near end of
the 1" pipe is .707" or a short 3/4".
DRB
Seola Creek
James Freeman on tue 27 jul 10
David...
Thanks for the help.
The hose is made specifically for natural gas, not propane. I am
certain that it is big enough, as I run an absolutely massive 9-burner
barbecue grill that puts out in excess of 100,000 BTU, 65,000 for just
the main burners. It is connected to the gas supply by 20 feet of
that same hose.
I have, according to the gas company, about 8" of pressure. The
piping is 3/4". I reduced it to 1/2", with a shut off valve and a
quick connect fitting for the hose.
...James
James Freeman
"All I say is by way of discourse, and nothing by way of advice.=3DA0 I
should not speak so boldly if it were my due to be believed."
-Michel de Montaigne
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
On Tue, Jul 27, 2010 at 1:38 AM, David Woof wrote:
> Hi James,
>
> what is your source pipe size and source delivery pressure for the natura=
=3D
l gas and how much gas volume available for conversion to BTU's do you expe=
=3D
ct to receive at the end of the 10' B'BQ hose typically used to deliver the=
=3D
much higher pressure and calories of propane?
>
>
>
> Or said this way: If one can easily "shut off" an open 3/4 inch pipe push=
=3D
ing 6 pounds with one's thumb, how much actual natural gas will be pushed t=
=3D
hru a 3/8 hose?
>
>
>
> More than adequate hose is a blessing and a good place to start the learn=
=3D
ing process. Then you can grow those half inches Mel is talking about.
>
>
>
Marcia Selsor on wed 28 jul 10
I have to go look at some very old purple dittos of a Don Bendel (ASU =3D
Flagstaff)=3D20
I built some in 1971. The oriface size seemed much smaller but there was =
=3D
5 holes in black pipe pendicular to the air column pipe (2.5 ") Built =3D
two burners..black pipe for the gas.
Marcia
They worked well woth propane.
Marcia
On Jul 28, 2010, at 10:39 PM, Dannon Rhudy wrote:
> James said:
> ............ I drilled it out to 1/8", and the heat rise increased to =3D
about
> 35 degrees per minute, which is still much too slow. One more step,
> up to 9/64", seemed to do the trick. The burner made that nice burner
> sound, and I was gaining about 70 degrees per minute. It of course
> slowed down as the temperature climbed (down to about 35 degrees per
> minute at the end of the firing), and I ended up hitting my target of
> 1650 degrees in 50 minutes, 14 seconds. This is slower than my goal
> of 45 minutes, but seems reasonable to me. I may bump the orifice up
> to 5/32", but haven't quite decided..... =3D20
>=3D20
>=3D20
> James, that seems a little slow to me,
> but it depends on some things. For the
> first firing, that seems ok. For subsequent
> firings, the kiln will already be very hot,
> even if you linger in getting work out,=3D20
> having the lid off, etc. So, the second,
> third and whatever firings should be faster.
>=3D20
> If the kiln SOUNDS right, then the likelihood
> is that it's pretty close. I have always found
> that in addition to the color inside the kiln,
> the sound is very important in judging what's
> going on inside. I fire all my kilns without
> much technical stuff, except for a probe in
> my bisque kiln. Everything else is by eye and
> ear. One develops the touch very soon. Or,
> as the colloquial is here: "there's just a little
> slight to it". Meaning, it's tricky but one
> learns.
>=3D20
> Kiln looks good, and it's a good size too.
> I don't just love top loaders for raku, I
> sometimes need to lift work out by hand, and
> it's too easy to get scorched. But for most
> tong work, just mind your eyelashes and all
> will be well.
>=3D20
> Carry on!
>=3D20
> regards
>=3D20
> Dannon Rhudy
>=3D20
>=3D20
>=3D20
> I thought I'd share my results with the orifice diameter question for
> those who find themselves in a similar situation. I first drilled the
> orifice to 7/64", based on 8 water column inches of natural gas. The
> burner had a faint roar, but not the deep, throaty growl one likes to
> hear. With this orifice, the kiln heated rather slowly, about 20
> degrees F per minute, and stalled out at about 950 degrees (all temps
> in F
> Is 50 minutes from a cold kiln to 1650 degrees a reasonable time for a
> raku kiln? It is faster than the raku kiln at the college, but I do
> not know if that one was "normal", or slow. Any input?
>=3D20
> For anyone curious, I posted some photos and descriptive text to my
> flickr page (www.flickr.com/photos/jamesfreemanstudio/). I mounted
> the entire affair atop a stripped down hydraulic surgical stretcher
> (doesn't everyone have one laying around?). This allows me to raise
> everything up for transport, wheel it out of the barn and to the
> firing area and gas supply, then lower it down for ease of loading and
> unloading. I plan to replace the stretcher with a low dolly on
> pneumatic tires which I can hitch to my garden tractor and tow to the
> firing site.
>=3D20
> Thanks again to everyone who responded both on and off list. Your
> input was both helpful and appreciated.
>=3D20
> All the best.
>=3D20
> ...James
>=3D20
> James Freeman
>=3D20
> "All I say is by way of discourse, and nothing by way of advice. I
> should not speak so boldly if it were my due to be believed."
> -Michel de Montaigne
>=3D20
> http://www.jamesfreemanstudio.com
> http://www.flickr.com/photos/jamesfreemanstudio/
> http://www.jamesfreemanstudio.com/resources
>=3D20
>=3D20
>=3D20
>=3D20
> On Mon, Jul 26, 2010 at 5:07 PM, James Freeman
> wrote:
>> I just finished converting an old Jenken 1 1/2 cubic foot square
>> electric toploader to a raku kiln. I have a really nice home made
>> weed burner-type burner made by a machinist friend. He drilled the
>> orifice for propane. The hole must be a numbered drill size, which I
>> do not have, as a 1/16" bit fits the hole loosely, while the 5/64"
>> does not fit at all.
>>=3D20
>> I want to run the burner on natural gas through a 10' gas hose made
>> for barbecue grills. Can anyone venture a guess as to what diameter =3D
I
>> should drill out the orifice in the burner? As yet no reply from the
>> gas company. I think they are avoiding the question. I did fire up
>> the burner just to see what would happen, and I got a weak and lazy
>> flame, so the orifice is definitely undersized.
>=3D20
Marcia Selsor
http://www.marciaselsor.com
James Freeman on wed 28 jul 10
Well, the raku kiln conversion is mostly done. Just a minor tweak to
the channels the damper slides in, plus attaching a remote handle to
raise the lid without getting toasted.
I thought I'd share my results with the orifice diameter question for
those who find themselves in a similar situation. I first drilled the
orifice to 7/64", based on 8 water column inches of natural gas. The
burner had a faint roar, but not the deep, throaty growl one likes to
hear. With this orifice, the kiln heated rather slowly, about 20
degrees F per minute, and stalled out at about 950 degrees (all temps
in F). I drilled it out to 1/8", and the heat rise increased to about
35 degrees per minute, which is still much too slow. One more step,
up to 9/64", seemed to do the trick. The burner made that nice burner
sound, and I was gaining about 70 degrees per minute. It of course
slowed down as the temperature climbed (down to about 35 degrees per
minute at the end of the firing), and I ended up hitting my target of
1650 degrees in 50 minutes, 14 seconds. This is slower than my goal
of 45 minutes, but seems reasonable to me. I may bump the orifice up
to 5/32", but haven't quite decided. This leads to a question:
Is 50 minutes from a cold kiln to 1650 degrees a reasonable time for a
raku kiln? It is faster than the raku kiln at the college, but I do
not know if that one was "normal", or slow. Any input?
For anyone curious, I posted some photos and descriptive text to my
flickr page (www.flickr.com/photos/jamesfreemanstudio/). I mounted
the entire affair atop a stripped down hydraulic surgical stretcher
(doesn't everyone have one laying around?). This allows me to raise
everything up for transport, wheel it out of the barn and to the
firing area and gas supply, then lower it down for ease of loading and
unloading. I plan to replace the stretcher with a low dolly on
pneumatic tires which I can hitch to my garden tractor and tow to the
firing site.
Thanks again to everyone who responded both on and off list. Your
input was both helpful and appreciated.
All the best.
...James
James Freeman
"All I say is by way of discourse, and nothing by way of advice.=3DA0 I
should not speak so boldly if it were my due to be believed."
-Michel de Montaigne
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
On Mon, Jul 26, 2010 at 5:07 PM, James Freeman
wrote:
> I just finished converting an old Jenken =3DA01 1/2 cubic foot square
> electric toploader to a raku kiln. =3DA0I have a really nice home made
> weed burner-type burner made by a machinist friend. =3DA0He drilled the
> orifice for propane. =3DA0The hole must be a numbered drill size, which I
> do not have, as a 1/16" bit fits the hole loosely, while the 5/64"
> does not fit at all.
>
> I want to run the burner on natural gas through a 10' gas hose made
> for barbecue grills. =3DA0Can anyone venture a guess as to what diameter =
I
> should drill out the orifice in the burner? =3DA0As yet no reply from the
> gas company. =3DA0I think they are avoiding the question. =3DA0I did fire=
up
> the burner just to see what would happen, and I got a weak and lazy
> flame, so the orifice is definitely undersized.
Dannon Rhudy on wed 28 jul 10
James said:
............ I drilled it out to 1/8", and the heat rise increased to =3D
about
35 degrees per minute, which is still much too slow. One more step,
up to 9/64", seemed to do the trick. The burner made that nice burner
sound, and I was gaining about 70 degrees per minute. It of course
slowed down as the temperature climbed (down to about 35 degrees per
minute at the end of the firing), and I ended up hitting my target of
1650 degrees in 50 minutes, 14 seconds. This is slower than my goal
of 45 minutes, but seems reasonable to me. I may bump the orifice up
to 5/32", but haven't quite decided..... =3D20
James, that seems a little slow to me,
but it depends on some things. For the
first firing, that seems ok. For subsequent
firings, the kiln will already be very hot,
even if you linger in getting work out,=3D20
having the lid off, etc. So, the second,
third and whatever firings should be faster.
If the kiln SOUNDS right, then the likelihood
is that it's pretty close. I have always found
that in addition to the color inside the kiln,
the sound is very important in judging what's
going on inside. I fire all my kilns without
much technical stuff, except for a probe in
my bisque kiln. Everything else is by eye and
ear. One develops the touch very soon. Or,
as the colloquial is here: "there's just a little
slight to it". Meaning, it's tricky but one
learns.
Kiln looks good, and it's a good size too.
I don't just love top loaders for raku, I
sometimes need to lift work out by hand, and
it's too easy to get scorched. But for most
tong work, just mind your eyelashes and all
will be well.
Carry on!
regards
Dannon Rhudy
I thought I'd share my results with the orifice diameter question for
those who find themselves in a similar situation. I first drilled the
orifice to 7/64", based on 8 water column inches of natural gas. The
burner had a faint roar, but not the deep, throaty growl one likes to
hear. With this orifice, the kiln heated rather slowly, about 20
degrees F per minute, and stalled out at about 950 degrees (all temps
in F
Is 50 minutes from a cold kiln to 1650 degrees a reasonable time for a
raku kiln? It is faster than the raku kiln at the college, but I do
not know if that one was "normal", or slow. Any input?
For anyone curious, I posted some photos and descriptive text to my
flickr page (www.flickr.com/photos/jamesfreemanstudio/). I mounted
the entire affair atop a stripped down hydraulic surgical stretcher
(doesn't everyone have one laying around?). This allows me to raise
everything up for transport, wheel it out of the barn and to the
firing area and gas supply, then lower it down for ease of loading and
unloading. I plan to replace the stretcher with a low dolly on
pneumatic tires which I can hitch to my garden tractor and tow to the
firing site.
Thanks again to everyone who responded both on and off list. Your
input was both helpful and appreciated.
All the best.
...James
James Freeman
"All I say is by way of discourse, and nothing by way of advice.=3DA0 I
should not speak so boldly if it were my due to be believed."
-Michel de Montaigne
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
On Mon, Jul 26, 2010 at 5:07 PM, James Freeman
wrote:
> I just finished converting an old Jenken =3DA01 1/2 cubic foot square
> electric toploader to a raku kiln. =3DA0I have a really nice home made
> weed burner-type burner made by a machinist friend. =3DA0He drilled the
> orifice for propane. =3DA0The hole must be a numbered drill size, which =
=3D
I
> do not have, as a 1/16" bit fits the hole loosely, while the 5/64"
> does not fit at all.
>
> I want to run the burner on natural gas through a 10' gas hose made
> for barbecue grills. =3DA0Can anyone venture a guess as to what diameter =
=3D
I
> should drill out the orifice in the burner? =3DA0As yet no reply from =3D
the
> gas company. =3DA0I think they are avoiding the question. =3DA0I did fire=
=3D
up
> the burner just to see what would happen, and I got a weak and lazy
> flame, so the orifice is definitely undersized.
douglas fur on sat 31 jul 10
James
I spent half of yesterday mucking about with my burners. I'd sculpted flam=
e
retention tips out of soft brick. I'd dropped and broke one of my initial
pair and made two more beefy ones. They were back-firing so I went back an=
d
measured the old. The old had a 5/8" dia throat compared to the 1"dia pipe
burner whereas the new ones had creot up to 3/4"dia. So back to the shop fo=
r
new one's with a 5/8" dia throat. (the design concept is to put a venturi
at the end of the burner to increase velocity making it harder for the flam=
e
to burn back to the orifice) This decrease in crossection area at the
narrowest from about 60% to 40% was crucial but I also impulsed and made th=
e
end of the F.R.T.'s (How do you pronounce this acronym, as if it had an "A"
in it?) bullet shaped instead of flat. This totally changed the character
of the flame from harsh and roaring to soft and quiet. ( the abrupt change
in the flat top produces more turbulence and faster mixing whereas the
bullet shape produces more laminar flow with the flame from the burner
surrounded by a parallel flow of induced air which is slower to mix with th=
e
flame[?]). At the end I cut off the bullet to give a small flat end. This
moved the flame back towards the shorter flame of the full flat top.
To add to totally the confusion I noticed when I lifted the F.R.T.'s air
would leak into the burner under the F.R.T. making the flame shorter and
more aggressive- go figger.
DRB
Seola Creek
douglas fur on sat 31 jul 10
James
I just looked at your pix. This burner looks topsy-turvy to what I've hear=
d
of burner design- which may belong with flat earth concepts such as
"sunrise" and "sunset" which work fine in daily practice but are all wrong.
As I understand it you want yer gas jet to shoot into a constriction/ventur=
i
so that it induces airflow into the burner to tmix with the gas. But in thi=
s
burner the perforated plate is such that the gas jet enters the buner after
the venturi and the inducesd air has to overcome the restrictions at the
plate to get to the gas and mix etc.
But if it works... whatthehey?
DRB
Seola Creek
David Woof on sat 31 jul 10
Hi Frank=3D2C
=3D20
YUP I know this stuff !!! I was just asking questions of James to direct=
=3D
his thinking and get him working out his questions. His off list respons=
=3D
e to me tells me he is on to it and will succeed with what he is doing. =3D=
20
=3D20
I believe we should all give so that all will come away understanding more =
=3D
than just being given formulas to blindly use.
=3D20
When it comes to directly answering some questions=3D2C I find it producti=
ve=3D
to ask the poster of the question to find/discover the answers from acquir=
=3D
ing an understanding of the underlying physics inspired by my "quest"-ions.=
=3D
You will notice that Mel directed him in much the same way. This is =
=3D
educational teaching in the root Latin sense of the word.
=3D20
David Woof
________________________________
=3D20
=3D20
Frank wrote: > Rule of thumb with natural gas: The longer the line from the=
=3D
meter=3D2C the larger (diameter) line you must have =3D2Cto the "fire box"=
=3D2C =3D
or you'll never=3D20
> reach temperture (above deep red)! =3D20
=3D20
> It all comes down to pressure vs volume! If you try to put out a house=3D=
20
> fire with a garden hose=3D2C you'll surely lose it all=3D2C because there=
jus=3D
t isn't=3D20
> enough volume. Use a fire-hose with the same amount of pressure as the=3D=
20
> garden horse and you'll save the house! Volia!
>=3D20
> The fire hose has both the volume AND the pressure required-Duuuuuh!
>=3D20
> Frank Colson
> www.r2d2u.net
>=3D20
> ----- Original Message -----=3D20
> From: "David Woof"
> To:
> Sent: Monday=3D2C July 26=3D2C 2010 10:38 PM
> Subject: Re: burner orifice size?
>=3D20
>=3D20
> Hi James=3D2C
>=3D20
> what is your source pipe size and source delivery pressure for the natura=
=3D
l=3D20
> gas and how much gas volume available for conversion to BTU's do you expe=
=3D
ct=3D20
> to receive at the end of the 10' B'BQ hose typically used to deliver the=
=3D
=3D20
> much higher pressure and calories of propane?
>=3D20
>=3D20
>=3D20
> Or said this way: If one can easily "shut off" an open 3/4 inch pipe push=
=3D
ing=3D20
> 6 pounds with one's thumb=3D2C how much actual natural gas will be pushed=
t=3D
hru a=3D20
> 3/8 hose?
>=3D20
>=3D20
>=3D20
> More than adequate hose is a blessing and a good place to start the learn=
=3D
ing=3D20
> process. Then you can grow those half inches Mel is talking about.
>=3D20
>=3D20
>=3D20
> Disclaimer: The foregoing is not offered as directions or advice. don't t=
=3D
ry=3D20
> this at home=3D3B asphyxiation=3D2C unconsciousness=3D2C explosion and de=
ath is=3D
likely=3D20
> to follow. Seek qualified=3D2C licensed assistance.
>=3D20
>=3D20
>=3D20
> Re. the gas company=3D3B I understand their avoiding your question becaus=
e =3D
of=3D20
> liability issues.
>=3D20
> Hire their tech and watch them come running. I know=3D2C I know!!! us cla=
y=3D
=3D20
> folks want to do it ourselves. Hopefully to learn and perhaps save money.=
=3D
=3D20
> But giving each other advice re electricity and gas is getting ever more=
=3D
=3D20
> risky!!! and we can't blame attorneys for the blame shifting litigiousnes=
=3D
s=3D20
> and growing evidence of stupidity.
>=3D20
>=3D20
>=3D20
> David Woof
>=3D20
> ________________________________________________________________________
> 9a. burner orifice size?
> Posted by: "James Freeman" jamesfreemanstudio@GMAIL.COM
> Date: Mon Jul 26=3D2C 2010 2:42 pm ((PDT))
>=3D20
> I just finished converting an old Jenken 1 1/2 cubic foot square
> electric toploader to a raku kiln. I have a really nice home made
> weed burner-type burner made by a machinist friend. He drilled the
> orifice for propane. The hole must be a numbered drill size=3D2C which I
> do not have=3D2C as a 1/16" bit fits the hole loosely=3D2C while the 5/64=
"
> does not fit at all.
>=3D20
> I want to run the burner on natural gas through a 10' gas hose made
> for barbecue grills. Can anyone venture a guess as to what diameter I
> should drill out the orifice in the burner? As yet no reply from the
> gas company. I think they are avoiding the question. I did fire up
> the burner just to see what would happen=3D2C and I got a weak and lazy
> flame=3D2C so the orifice is definitely undersized.
>=3D20
> Thanks.
>=3D20
> ...James
>=3D20
> James Freeman
>=3D20
>=3D20
>=3D20
>=3D20
>=3D20
>=3D20
> _________________________________________________________________
> Hotmail is redefining busy with tools for the New Busy. Get more from you=
=3D
r=3D20
> inbox.
> http://www.windowslive.com/campaign/thenewbusy?ocid=3D3DPID28326::T:WLMTA=
GL=3D
:ON:WL:en-US:WM_HMP:042010_2=3D3D=3D20
>=3D20
=3D
James Freeman on sat 31 jul 10
Douglas...
Thanks for that great information.
Yes, my burner is a simple "weed burner". It is a very basic affair,
and lacks a venturi. Or, as Nils put it, it is a venturi, just a
particularly inefficient one.
Both you and Hank observed that this primitive burner design would
have trouble entraining sufficient air for good combustion. In that,
both of you appear to be correct. As I mentioned in a previous post,
when I drilled the orifice to 9/64", I was able to heat the kiln to
temperature in 50 minutes. As the consensus opinion was that this was
too slow, I re-drilled the orifice to 5/16" yesterday. When I fired
the kiln, my rate of temperature climb actually decreased
significantly. There was also now a visible flame coming from the
flue, which tells me that the burner was indeed not able to entrain
sufficient air for full combustion. I had to back off the gas supply,
and in the end it took a full hour to heat the kiln.
At this point I seem to have three options. I can leave the orifice
at 5/16" and just back off the gas, I can weld up the orifice then
re-drill it back to 9/64" and be happy with 50 minutes heating time,
or I can mount one of my proper Pyronics venturi burners (I believe
they are size number 8). If anyone has other ideas, I would be happy
to hear them. (Note: re-heating for the second load took only about
10 minutes)
I would also like to note that the clay I used is my standard,
do-anything, Rovin You Betcha (RO-01). It suffered no ill effects
during firing and quenching, even with the second load which was
placed directly on the hot kiln shelf. I did, however, order some
Rovin raku clay on John Post's advice for the kids to use. And John,
that glaze was spectacular, thank you.
Thanks again to everyone for your help, both on and off list.
...James
James Freeman
"All I say is by way of discourse, and nothing by way of advice.=3DA0 I
should not speak so boldly if it were my due to be believed."
-Michel de Montaigne
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
On Sat, Jul 31, 2010 at 2:08 PM, douglas fur <23drb50@gmail.com> wrote:
> James
> I just looked at your pix.=3DA0 This burner looks topsy-turvy to what I'v=
e =3D
heard
> of burner design- which may belong with flat earth concepts such as
> "sunrise" and "sunset" which work fine in daily practice but are all wron=
=3D
g.
> As I understand it you want yer gas jet to shoot into a constriction/vent=
=3D
uri
> so that it induces airflow into the burner to tmix with the gas. But in t=
=3D
his
> burner the perforated plate is such that the gas jet enters the buner aft=
=3D
er
> the venturi and the inducesd air has to overcome the restrictions at the
> plate to get to the gas and mix etc.
> But if it works... whatthehey?
> DRB
> Seola Creek
>
Marcia Selsor on sat 31 jul 10
I am sorry I haven't found the Don Bendel propane burner design. I have =3D
had a few family issues to deal with.
It was not expensive to build and worked great on propane.
Marcia
On Jul 31, 2010, at 2:40 PM, James Freeman wrote:
> Douglas...
>=3D20
> Thanks for that great information.
>=3D20
> Yes, my burner is a simple "weed burner". It is a very basic affair,
> and lacks a venturi. Or, as Nils put it, it is a venturi, just a
> particularly inefficient one.
>=3D20
> Both you and Hank observed that this primitive burner design would
> have trouble entraining sufficient air for good combustion. In that,
> both of you appear to be correct. As I mentioned in a previous post,
> when I drilled the orifice to 9/64", I was able to heat the kiln to
> temperature in 50 minutes. As the consensus opinion was that this was
> too slow, I re-drilled the orifice to 5/16" yesterday. When I fired
> the kiln, my rate of temperature climb actually decreased
> significantly. There was also now a visible flame coming from the
> flue, which tells me that the burner was indeed not able to entrain
> sufficient air for full combustion. I had to back off the gas supply,
> and in the end it took a full hour to heat the kiln.
>=3D20
> At this point I seem to have three options. I can leave the orifice
> at 5/16" and just back off the gas, I can weld up the orifice then
> re-drill it back to 9/64" and be happy with 50 minutes heating time,
> or I can mount one of my proper Pyronics venturi burners (I believe
> they are size number 8). If anyone has other ideas, I would be happy
> to hear them. (Note: re-heating for the second load took only about
> 10 minutes)
>=3D20
> I would also like to note that the clay I used is my standard,
> do-anything, Rovin You Betcha (RO-01). It suffered no ill effects
> during firing and quenching, even with the second load which was
> placed directly on the hot kiln shelf. I did, however, order some
> Rovin raku clay on John Post's advice for the kids to use. And John,
> that glaze was spectacular, thank you.
>=3D20
> Thanks again to everyone for your help, both on and off list.
>=3D20
> ...James
>=3D20
> James Freeman
>=3D20
> "All I say is by way of discourse, and nothing by way of advice. I
> should not speak so boldly if it were my due to be believed."
> -Michel de Montaigne
>=3D20
> http://www.jamesfreemanstudio.com
> http://www.flickr.com/photos/jamesfreemanstudio/
> http://www.jamesfreemanstudio.com/resources
>=3D20
>=3D20
>=3D20
>=3D20
> On Sat, Jul 31, 2010 at 2:08 PM, douglas fur <23drb50@gmail.com> =3D
wrote:
>> James
>> I just looked at your pix. This burner looks topsy-turvy to what =3D
I've heard
>> of burner design- which may belong with flat earth concepts such as
>> "sunrise" and "sunset" which work fine in daily practice but are all =3D
wrong.
>> As I understand it you want yer gas jet to shoot into a =3D
constriction/venturi
>> so that it induces airflow into the burner to tmix with the gas. But =3D
in this
>> burner the perforated plate is such that the gas jet enters the buner =
=3D
after
>> the venturi and the inducesd air has to overcome the restrictions at =3D
the
>> plate to get to the gas and mix etc.
>> But if it works... whatthehey?
>> DRB
>> Seola Creek
>>=3D20
>=3D20
Marcia Selsor
http://www.marciaselsor.com
ivor and olive lewis on sun 1 aug 10
Dear James Freeman, You say...
"Both you and Hank observed that this primitive burner design would have
trouble entraining sufficient air for good combustion. In that, both of yo=
u
appear to be correct. "...
Perhaps there is a need for a secondary air supply, either as an annular
space between the rim of the burner orifice and the fireport or via
"Mouseholes". These are features not indexed by Rhodes, Olsen, Hammer or
Nils Lou.
Mouseholes are narrow passages or tunnels, designed to be left in the
brickwork, through which additional air can be drawn by the draught induced
by the stack. This flow of air is necessary for the complete combustion of
your fuel.
Best regards,
Ivor Lewis,
REDHILL,
South Australia
ivor and olive lewis on mon 2 aug 10
Additional references,
Michael Cardew does mention Mouseholes in "Pioneer Pottery", ISBN
0-582-12624-X.
Bernard Leach, "A Potter's Book" Faber, 1967, has an illustration of a
climbing kiln that has a Mousehole incorporated in its design.
Regards,
Ivor Lewis,
REDHILL,
South Australia
douglas fur on sat 7 aug 10
James
(happy firing)
About the experiments. The short version is I concluded that the diameter o=
f
my burner tube was too small. This resulted in a slower velocity in the
tube and therefore less air entrained which resulted in poor combustion.
In Olsen's *Kiln Book* I saw how the velocity in the tube had to match the
flame speed for your gas type. Putting flame speed together with burner
output I came up with a formula-
A (cross section air of tube) X Flame Speed ( in feet/minute from internet)
=3DVolume of Combustion Air (In cubic feet/minute)
Solving for A you divide the air volume by the flame speed end end up with
the cross section area in S.F. from which you can get to the diameter of th=
e
tube in inches.
This is my idea of Fun (?)
DRB
Seola Creek
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