Michael Hamlin on fri 20 aug 99
Hey Folks,
I'm trying to find the right size propane tank to use for my kiln....the kiln
is small with interior dimensions of 18" x 17" . I use it for experiments,
firing to ^6. When I lived in Ohio I used a 100 lb. tank and it never froze
up......Here in New Mexico the propane company told me if I used a 120
gallon tank that it would freeze up. They explained to me that there is a
pressure difference and recommended I use a 250 gallon tank. I fire this
kiln once a week and I would like to use the 120 gallon tank simply for its
small size. However if I must use something larger to prevent freeze up then
so be it.... Can anyone tell me if the propane companies statement is true?
I get so much conflicting advice on propane tanks that I become cunfused and
frustrated.
Thank you all for your help!
Michael in Taos, New Mexico
the Gallaghers on sat 21 aug 99
I was told that to keep a tank from freezing up you can submerse it half way
into hot water and warm it up. Of course that gets hard to do with really
heavy tanks.
Michelle
In Oregon
-----Original Message-----
From: Michael Hamlin
To: CLAYART@LSV.UKY.EDU
Date: Friday, August 20, 1999 11:47 AM
Subject: Appropriate Propane tank size
>----------------------------Original message----------------------------
>Hey Folks,
>I'm trying to find the right size propane tank to use for my kiln....the
kiln
>is small with interior dimensions of 18" x 17" . I use it for experiments,
>firing to ^6. When I lived in Ohio I used a 100 lb. tank and it never
froze
>up......Here in New Mexico the propane company told me if I used a 120
>gallon tank that it would freeze up. They explained to me that there is a
>pressure difference and recommended I use a 250 gallon tank. I fire this
>kiln once a week and I would like to use the 120 gallon tank simply for its
>small size. However if I must use something larger to prevent freeze up
then
>so be it.... Can anyone tell me if the propane companies statement is
true?
>I get so much conflicting advice on propane tanks that I become cunfused
and
>frustrated.
>Thank you all for your help!
>Michael in Taos, New Mexico
John Rodgers on sat 21 aug 99
Michael, I can't answer your question directly, but there could be some truth to
what the propane company says. I haven't had the pleasure of firing with propane
in the higher elevations of New Mexico, but the atnmospheric pressure at the
higher elevations could make a difference in the the way the pressure in the
tank is affected. You might consider trying the one tank. It there is a freezing
problem, couple another one to it. Use as many as you need. I realize of course
that there is a cost efficiency involved....several 100 pounders or 120 gallon
units as opposed to the cost of one big 250 gallon tank.
Thing is, you won't know unless you try it!
One thing to consider however, and that is as pressure in the tank drops, the
temperature begins to fall. The bigger the liquid volume in the tank, the longer
it will take for the temperature to drop low enough to begin to cause gas flow
problems. The step up from 120 to the 250 may be just enough to keep the tank
from freezing.
Good luck.
John Rodgers
Espanola NM.
Michael Hamlin wrote:
> ----------------------------Original message----------------------------
> Hey Folks,
> I'm trying to find the right size propane tank to use for my kiln....the kiln
> is small with interior dimensions of 18" x 17" . I use it for experiments,
> firing to ^6. When I lived in Ohio I used a 100 lb. tank and it never froze
> up......Here in New Mexico the propane company told me if I used a 120
> gallon tank that it would freeze up. They explained to me that there is a
> pressure difference and recommended I use a 250 gallon tank. I fire this
> kiln once a week and I would like to use the 120 gallon tank simply for its
> small size. However if I must use something larger to prevent freeze up then
> so be it.... Can anyone tell me if the propane companies statement is true?
> I get so much conflicting advice on propane tanks that I become cunfused and
> frustrated.
> Thank you all for your help!
> Michael in Taos, New Mexico
nikom chimnok on sat 21 aug 99
Hello Michael,
I once had a kiln about the same size as yours which I fired to cone
5 in about 6 hours. The (possible) big difference was that I was using LNG
(Liquified Natural Gas) not propane. In any event, using a hundred POUND
tank I never had a freeze up problem until the last firing, when the tank
was almost empty. Then I would put it in a tub of water, and maybe even add
hot water to get the now low pressure liquid to vaporize.
What do they mean by pressure difference? The difference in air
pressure because of altitude? This may call for a taller chimney, but won't
effect the tank any. Or is the propane in the tank under a lower pressure
there? That could be problematic, and call for a larger tank. Ask more
questions.
Regards,
Nikom in Thailand, where there is nothing available but 100 pound tanks, and
everyone with big kilns persists in using them in batteries in tanks of
water with a propane heater under the tank. Which makes everyone in the
civilized world cringe, but I have yet to hear of an accident resulting
therefrom.
*****************************************************
At 14:46 20/8/99 EDT, you wrote:
>----------------------------Original message----------------------------
>Hey Folks,
>I'm trying to find the right size propane tank to use for my kiln....the kiln
>is small with interior dimensions of 18" x 17" . I use it for experiments,
>firing to ^6. When I lived in Ohio I used a 100 lb. tank and it never froze
>up......Here in New Mexico the propane company told me if I used a 120
>gallon tank that it would freeze up. They explained to me that there is a
>pressure difference and recommended I use a 250 gallon tank. I fire this
>kiln once a week and I would like to use the 120 gallon tank simply for its
>small size. However if I must use something larger to prevent freeze up then
>so be it.... Can anyone tell me if the propane companies statement is true?
>I get so much conflicting advice on propane tanks that I become cunfused and
>frustrated.
>Thank you all for your help!
>Michael in Taos, New Mexico
>
>
M. R. W. on sun 22 aug 99
Hi Michael-
I have just read all of the responses to your tank
size question and I am a little surprised at some
of the misconceptions or lack of knowledge some
have about propane. So here goes! First, be sure
that your supplier is in fact giving you propane
and not butane or a propane/butane mix. In the
southern states butane is a very common fuel source,
as the evironmental (outside) temperature is warm
enough to keep the butane evaporating. Here is what
is going on in the propane or butane tank-if it is
not being used it acts just like any other liquid
and will warm or cool depending on the air temp.
around the tank. But things change in there when
you start to 'use' it. Both fuels have a certain
tendency to vaporize (vapor pressure) if allowed to,
such as when you open the valve. The pressure in
a propane tank is approx. 100 psi (more or less
depending on the temperature of the liquid in the
tank). I am not sure of the normal tank pressure
of butane-it is somewhat less as its vapor pressure
(tendency to evaporate) is less than is propane.
However, in either case, when you open the valve
and allow some vapor th escape thing change in that
tank! As with any liquid that evaporates, it takes
energy to make it happen! With propane (et. al)
this energy is needed quickly and therefore it comes
from the remaining liquid in the tank-AND THIS LIQUID
COOLS DOWN! The faster you use the fuel the more the
remaining liquid cools, and the more it cools the
less the vapor pressure. Realize that the remaining
liquid is acting as your immediate 'heat sink' and
if this heat sink is to small for the rate of use
the liquid will get so cold that the vapor pressure
may be reduced to an un-usable level. Thus, the
argument for the larger tank (Larger Heat Sink!!!).
Along this line, the codes state that you can place
a 120 gal. tank next to a building, but any tank
larger than that will have to be at least 10 ft away
unless you have an acceptable firewall for the larger
tank . Hope this helps-message back any of your
questions. -Reg Wearley in Big Arm, MT
--- Michael Hamlin wrote:
> ----------------------------Original
> message----------------------------
> Hey Folks,
> I'm trying to find the right size propane tank to
> use for my kiln....the kiln
> is small with interior dimensions of 18" x 17" . I
> use it for experiments,
> firing to ^6. When I lived in Ohio I used a 100 lb.
> tank and it never froze
> up......Here in New Mexico the propane company told
> me if I used a 120
> gallon tank that it would freeze up. They explained
> to me that there is a
> pressure difference and recommended I use a 250
> gallon tank. I fire this
> kiln once a week and I would like to use the 120
> gallon tank simply for its
> small size. However if I must use something larger
> to prevent freeze up then
> so be it.... Can anyone tell me if the propane
> companies statement is true?
> I get so much conflicting advice on propane tanks
> that I become cunfused and
> frustrated.
> Thank you all for your help!
> Michael in Taos, New Mexico
>
__________________________________________________
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Tom Wirt on sun 22 aug 99
. When I lived in Ohio I used a 100 lb. tank and it never froze
> >up......Here in New Mexico the propane company told me if I used a 120
> >gallon tank that it would freeze up. They explained to me that there is
a
> >pressure difference and recommended I use a 250 gallon tank. I fire this
> >kiln once a week and I would like to use the 120 gallon tank simply for
its
> >small size. However if I must use something larger to prevent freeze up
then
> >so be it.... Can anyone tell me if the propane companies statement is
true?
There are several issues going on here. One is that there is a big
difference between a 100 LB tank and a 100 gallon tank. The 100 gallon is
considerably bigger.
With propane, as has been stated, bigger is better...it's the SURFACE AREA
of the propane that counts in freeze. You use larger area to keep getting
gas even when the tank gets cold. And it is tank temp that determines the
pressure in the tank. As propane (or any liquid) goes through the phase
change to a gas, there is cooling. As the temp of the tank goes down, the
LP liquid is less able to vaporize (maintain vapor pressure). We have a
1000 gallon tank and on the coldest days it will run about 10 lbs. of output
pressure. Normally it's at 100 lbs. pressure. But we run the kiln at 11
inches of pressure WC (water column) which is less than 1 LB. per sq. inch,
so the low pressure works.
All the ice around the tank and/or valve is not the problem...it only shows
that the tank is cold and forming ice from the air moisture.
Tilting the smaller tanks will give you more surface area, just be sure that
the liquid propane can't get to the valve.
As was suggested, talk to your propane company and get the straight poop.
Our 1000 gallon tank costs $79 per year to lease. The only downside is that
it ties us (by law) into using only the supplying company. But we shop
prices around with the neighbors anyway just to make sure it's in
line...currently about 63c per gallon.
Tom Wirt
Ingeborg Foco on mon 23 aug 99
Michael,
I've been reading the posts on propane tanks and would like to add that there
is much more to this equation than size of tank.
The size of the line and how far to your burners is very critical. My
personal experience has been that most propane people don't know enough about
kilns. You can tell them the BTU's of your burner system but it still
doesn't compute on their charts or their knowledge. (If you're a propane
supplier and know this stuff--I'm not trying to irritate or belittle) I
ended up redoing my lines twice (very expensive) because these people didn't
know what they were talking about. The further away from your kiln the
larger the pipe should be ---it's best to keep the runs short and limit the
bends. Code states the tank must be 10 feet from the heat source. If you
can do that ---do it. Then at 10 feet have at least a 3/4" pipe and an inch
if you have a lot of elbows or are further away..
The longer you fire, the size of your line, the type ofburners, the
temperature all affect the vaporization of the liquid propane and it's the
vapor you use. Hope this helps to add more info which will then help you
decide what's best..
Ingeborg.
Bruce Girrell on mon 23 aug 99
I may have missed it but in all this talk about tanks freezing, I haven't
seen anyone mention Nils's liquid propane burner system. The tank _can't_
freeze up because the vaporization of the fuel is done at the burner, rather
than in the tank. Inside the tank, only a small amount of propane needs to
evaporate to replace the volume of liquid being drawn off.
Bruce Girrell
in Northern Michigan
who probably has _insufficient_ fear of kilns (a different thread, I know)
Andrew Buck on mon 30 aug 99
Hi All,
Bruce is right about reducing the tank freezing problem by taking the
propane out as a liquid. However, you have to remember that to do this
you have to have a propane tank that is equipped with a dip-tube delivery
system which takes the liquid from the bottom of the tank rather than the
gas from the top. Not all propane tanks are set up in this manner.
Also, the piping has to be designed to handle the full vapor pressure of
the propane (approximately 260 PSI) where as the gas is usually reduced in
pressure at the tank outlet to something like 10 to 25 PSI. Any break in
the piping will produce a bigger gas leak from liquid, even with a closed
valve at the tank, so the piping will, per building codes and as a general
safety precaution, probably need better protection and stricter
inspection. Liquid delivery is an option, but, all things considered, I
opted for a bigger tank.
Andy Buck
Raincreek Pottery
Port Orchard, Washington
On Mon, 23 Aug 1999, Bruce Girrell wrote:
> ----------------------------Original message----------------------------
> I may have missed it but in all this talk about tanks freezing, I haven't
> seen anyone mention Nils's liquid propane burner system. The tank _can't_
> freeze up because the vaporization of the fuel is done at the burner, rather
> than in the tank. Inside the tank, only a small amount of propane needs to
> evaporate to replace the volume of liquid being drawn off.
>
> Bruce Girrell
> in Northern Michigan
> who probably has _insufficient_ fear of kilns (a different thread, I know)
>
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