jcjm on sun 27 feb 00
It seems kind of an accepted general rule that when firing with propane
tanks, they "freeze up" but does anybody know why? Do the tanks lose
pressure as they're emptying or is that just a consequence of another
phenomenon? Besides shaking the tank and pouring hot water over it, are
there any other ways of deterring it? Thanks for any help.
Jean-Marc in Montreal shaking and relaying the little 20lb barbeque tanks.
Cindy Strnad on mon 28 feb 00
Jean-Marc,
The propane tanks freeze up when a high proportion of the propane they
contain is used quickly. You're converting compressed, liquid propane to
gaseous propane, and that phase change causes the cooling. The solution to
this is to get a larger tank.
Cindy Strnad
earthenv@gwtc.net
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
WHew536674@cs.com on mon 28 feb 00
Jean-Marc
Propane gas goes from a liquid to a gas and requires heat in the process. So
when firing the propane cools down and you have a problem. I experienced the
same problem the first time I fired my Raku kiln with propane. So, I got
another 5 pound tank, lasted a little longer, but not long enough and both
tanks froze up, so I said the hell with it, and got a 100 pound tank, and all
has been right with the world since. I get about 3 Raku firings from it, and
it is still about one forth full after. Then I have the man come out and fill
it again. It cost me about $30 to fill it up. When it was new, it was about
$175 for the tank and fill up. Worth it because now I never have to worry.
Joyce A.
Mission, TX : Where it is so hot most of the time one would think nothing
could freeze up, or does except propane.
Mason Batchelder on mon 28 feb 00
the best answer is to get a larger tank like a 100# tank or a couple in
tandum.the more a burner takes per minute to fire it the more likely it will
freeze the tank.
ferenc jakab on mon 28 feb 00
Jean-Marc,
The propane gas that comes out of the burner has been evaporated from the
liquid gas in the bottle. As the gas is drawn off the liquid in the bottle
expands and in expanding it loses heat/energy. If the draw off is too rapid
then the liquid expands so rapidly and loses heat so rapidly that it
freezes. one solution to this problem that I have seen work quit well is to
stand the bottle/bottles in 44 gallon drums full of water. Another solution
is to daisy-chain several bottles so that the draw off is spread out over a
much larger amount of liquid.
A sculptor friend of mine connects 4 bottle and stands them in drums of
water to run his bronze furnace.
Feri.
Dorothy Weber on mon 28 feb 00
We found that when our kiln required more pressure than the tanks could
really deliver that they froze up and kiln would approach stalling. This is
easily solved by having your supplier provide a larger tank. As to
preventing the tanks from freezing up, there isn't really much you can do,
except in my earlier hobby of flying hot air balloons we used "tank warmers"
to heat the propane. These were insulated blankets that contained heat tape,
which would be plugged in the night before the flight so by morning the
propane was around 70F or so, no hotter. I have never seen these for larger
tanks, they were use on small 10 and 20 Gallon tanks. I think the real
answer is the larger tank or fire on a warmer day? John Weber
Ronan ORourke on mon 28 feb 00
Hello Jean-Marc
As you draw gas off the pressure in the tank drops, this allows more of
the liquid to turn to gas.
For liquid to turn to gas takes energy (you have to heat water to turn
it into steam)
This energy comes from the bottle and its surroundings, take too much
gas too quickly and the bottle freezes up and you loose pressure.
Do not except this! The solution is a lager resavoir of gas ( larger
heat sink), i.e. get a larger bottle or link several in parallel.
Hope this helps,
Ronan, Wolverhampton UK
-----Original Message-----
From: jcjm
To: CLAYART@LSV.UKY.EDU
Date: 28 February 2000 01:40
Subject: freezing gas tanks
----------------------------Original message----------------------------
It seems kind of an accepted general rule that when firing with propane
tanks, they "freeze up" but does anybody know why? Do the tanks lose
pressure as they're emptying or is that just a consequence of another
phenomenon? Besides shaking the tank and pouring hot water over it, are
there any other ways of deterring it? Thanks for any help.
Jean-Marc in Montreal shaking and relaying the little 20lb barbeque tanks.
Sara JH Ashodian on mon 28 feb 00
jean-marc
i seem to remember doing a raku with propane where the tank was placed in a
tub of water to about the 1/2 way point of the tank - we did not have a
freezing problem
sara
--
Sara JH Ashodian
Sash Arts Studio
----------
>From: jcjm
>To: CLAYART@LSV.UKY.EDU
>Subject: freezing gas tanks
>Date: Sun, Feb 27, 2000, 9:39 PM
>
> ----------------------------Original message----------------------------
> It seems kind of an accepted general rule that when firing with propane
> tanks, they "freeze up" but does anybody know why? Do the tanks lose
> pressure as they're emptying or is that just a consequence of another
> phenomenon? Besides shaking the tank and pouring hot water over it, are
> there any other ways of deterring it? Thanks for any help.
>
> Jean-Marc in Montreal shaking and relaying the little 20lb barbeque tanks.
Bruce Girrell on mon 28 feb 00
>It seems kind of an accepted general rule that when firing with propane
>tanks, they "freeze up" but does anybody know why? Do the tanks lose
>pressure as they're emptying or is that just a consequence of another
>phenomenon?
Jean-Marc,
The tanks freeze because the propane is stored as a liquid, but used as a
gas. It takes energy - a _lot_ of energy - to convert the liquid to gas,
just as it takes a lot of energy to boil water. The difference is that there
is no outside heat source to do the boiling as there is with the kettle of
water, so the heat is absorbed from the liquid itself and from the
surrounding environment. Since there is nothing to replace the heat used in
evaporation, the temperature of the liquid drops. The tanks lose pressure
only as a result of the temperature drop. If the tanks are supplied with
enough heat to supply convert the liquid to gas, then the pressure will stay
the same.
>Besides shaking the tank and pouring hot water over it, are
>there any other ways of deterring it? Thanks for any help.
Shaking the tank is effective only for very short periods of time, since
what you are doing is giving the liquid just a bit more heat to work with by
letting it come in contact with warmer parts of the tank.
Hot water over the tanks will work, but I am always concerned that the tank
that I do that to will be the one that has developed a weak spot and the
sudden thermal shock of the hot water will split the tank. I don't do this
anymore.
I find that the best solution for me is to set the tanks in large buckets of
water. The water doesn't have to be hot or even warm. As long as it is
liquid, there is enough heat in it to give to the propane. If the water
starts icing up, then you can add more water to the buckets. If you want to
add warm water, fine. The extra mass of the water in the buckets will
greatly diminish any thermal shock to the tanks.
Another option is to use a tank (usually 250 gallons or larger) that is
designed to lay on its side. The larger liquid volume and larger evaporation
surface area minimize the frosting problems.
Finally, there is a solution to the problem that completely avoids the
gas-into-liquid problem entirely. Nils Lou has developed burners that use
the liquid propane directly. Much like rocket engines, the liquid is turned
into gas by the heat of the burner's flame just before the gas is used .
(Nils - if the credit should go to another, let me know). If I recall
correctly, these burners are about the same price as "normal" burners. The
primary difference is that you must get a "dip tube" installed in your
propane tanks (by the propane company) that allows the liquid to be drawn
off the bottom of the tank and the tubing going to the burners must be
properly rated for handling the liquid.
Marc Ward - If you're out there reading this, could you say a few things
about these burners? What about safety shutoffs for liquid systems? Building
code concerns? Experiences?
Bruce Girrell
in Northern Michigan, where we have had a major thaw and the sun is actually
shining today!
Brett Jones on mon 28 feb 00
--- jcjm wrote:
> ----------------------------Original
> message----------------------------
> It seems kind of an accepted general rule that when
> firing with propane
> tanks, they "freeze up" but does anybody know why?
> Do the tanks lose
> pressure as they're emptying or is that just a
> consequence of another
> phenomenon? Besides shaking the tank and pouring
> hot water over it, are
> there any other ways of deterring it
My understanding of this phenomenon is that the
propane in the tank is a liquid under pressure. When
you release some of the pressure by opening the valve,
the surface of the liquid will evaporate or sublimate
( I'm not sure ) into a gas. This change of state
requires energy, which it steals from the surrounding
environment ( through the walls of the tank by
conduction ). As this process continues, the surface
of the liquid propane gets colder and colder.
Eventually it freezes and prevents the creation of
more gas, even though the tank still has propane left
in it.
What I do is to keep the surface of the tank from
icing up, thereby suppling the heat needed for the
change of state in the tank.
The danger is in the amount of heat used to do this.
You don't want to heat the tank so much that you
increase the pressure inside the tank past what it's
designed for safe use.
Two ways to approach this are:
1.) The low tech way ( and safer ) is if it's a sunny
day, take a black or dark green garbage bag and wrap
the tank with it. Rotate the tank occaionally to
distribute the warmth.
2.) The second way is if you're fairly handy and
gadget inclined, make a water bath for the tank. Do
not use hot water. The only thing you need to
accomplish is to keep the surface of the tank above
the freezing point. The reason that this method is a
little trickier is because the tank will want to roll
and bob in the water bath. Securing it with sturdy
wire
and many attatchment points will help to keep it
upright.
I've taken this one step further and added a garden
pond pump to recirculate warm water from a pipe placed
near the kiln to pick up heat from the firing. You
should test the water with you hand often to ensure
that is is no more than just luke warm to cool. It
should not be cold or hot.
Hope this helps
All the best
Brett
Been lurking for months and finally had something to
contribute!
__________________________________________________
Do You Yahoo!?
Talk to your friends online with Yahoo! Messenger.
http://im.yahoo.com
Norman van der Sluys on mon 28 feb 00
The solution is to use a larger tank. The conversion (decompression) from
liquid to gas demands energy which is taken from the surroundings in the form
of heat.When the surroundings are a relatively small area such as your 20lb
tank, the resulting temperature drop is enough to block the flow of gas to the
line. A larger volume tank means more mass for the heat to come from, thus
less likelihood of freezeup. Axner sells a burner system which performs the
necessary change from liquid to gas in the burner thus eliminating the
problem, so they say. It requires the installation of a dip tube in the tank.
Don't try this at home, folks. It has to be done by your propane supplier.
Norman van der Sluys in Western Michigan where the first bluebirds have
arrived at my bird feeder - a sighting confirmed by a similar occurrance at a
neighbor's place and a full month early!
jcjm wrote:
> ----------------------------Original message----------------------------
> It seems kind of an accepted general rule that when firing with propane
> tanks, they "freeze up" but does anybody know why? Do the tanks lose
> pressure as they're emptying or is that just a consequence of another
> phenomenon? Besides shaking the tank and pouring hot water over it, are
> there any other ways of deterring it? Thanks for any help.
>
> Jean-Marc in Montreal shaking and relaying the little 20lb barbeque tanks.
Dewitt on mon 28 feb 00
What size raku kiln are you firing and how many burners do you use? With
my 2ft high, 18" diameter raku kiln and a single burner, I get about 8 - 10
firings out of a 40 lbs tank.
deg
At 15:34 2/28/00 -0500, you wrote:
>----------------------------Original message----------------------------
>Jean-Marc
>Propane gas goes from a liquid to a gas and requires heat in the process. So
>when firing the propane cools down and you have a problem. I experienced the
>same problem the first time I fired my Raku kiln with propane. So, I got
>another 5 pound tank, lasted a little longer, but not long enough and both
>tanks froze up, so I said the hell with it, and got a 100 pound tank, and all
>has been right with the world since. I get about 3 Raku firings from it, and
>it is still about one forth full after. Then I have the man come out and fill
>it again. It cost me about $30 to fill it up. When it was new, it was about
>$175 for the tank and fill up. Worth it because now I never have to worry.
>Joyce A.
>Mission, TX : Where it is so hot most of the time one would think nothing
>could freeze up, or does except propane.
Nils Lou on tue 29 feb 00
A solution so far not mentioned is to use a liquid withdrawal burner that
draws the propane off in liquid form. The vaporization takes place at the
burner instead of inside the tank, therefore, there is no freeze-up and
you can use every drop without loss of pressure. To draw off the propane
as a liquid simply turn the tank upside down. The burners are available
from Axners. Nils Lou
On Mon, 28 Feb 2000, Dorothy Weber wrote:
> ----------------------------Original message----------------------------
> We found that when our kiln required more pressure than the tanks could
> really deliver that they froze up and kiln would approach stalling. This is
> easily solved by having your supplier provide a larger tank. As to
> preventing the tanks from freezing up, there isn't really much you can do,
> except in my earlier hobby of flying hot air balloons we used "tank warmers"
> to heat the propane. These were insulated blankets that contained heat tape,
> which would be plugged in the night before the flight so by morning the
> propane was around 70F or so, no hotter. I have never seen these for larger
> tanks, they were use on small 10 and 20 Gallon tanks. I think the real
> answer is the larger tank or fire on a warmer day? John Weber
>
Paul Lewing on tue 29 feb 00
I once had a studio partner who, after the water bath didn't work any
more, would warm the tank up by pulling a burner on a flexible hose out
of the kiln and pointing it at the tank. This is a good way to make
yourself eligible for the Darwin Awards. Those are given to people who
take themselves out of the gene pool in particularly spectacular and
foolish ways.
Paul Lewing, Seattle
Stephen Mills on tue 29 feb 00
We run our gas tanks under a light cold shower when they show signs of
frosting (no need for hot water, cold is warmer than liquid gas). Means
we fire 'em right to the end (I do object to giving gas back to the
company when I've paid for it!).
Steve
Bath
UK
In message , Sara JH Ashodian writes
>----------------------------Original message----------------------------
>jean-marc
>
>i seem to remember doing a raku with propane where the tank was placed in a
>tub of water to about the 1/2 way point of the tank - we did not have a
>freezing problem
>
>sara
>--
>Sara JH Ashodian
>Sash Arts Studio
>
>----------
>>From: jcjm
>>To: CLAYART@LSV.UKY.EDU
>>Subject: freezing gas tanks
>>Date: Sun, Feb 27, 2000, 9:39 PM
>>
>
>> ----------------------------Original message----------------------------
>> It seems kind of an accepted general rule that when firing with propane
>> tanks, they "freeze up" but does anybody know why? Do the tanks lose
>> pressure as they're emptying or is that just a consequence of another
>> phenomenon? Besides shaking the tank and pouring hot water over it, are
>> there any other ways of deterring it? Thanks for any help.
>>
>> Jean-Marc in Montreal shaking and relaying the little 20lb barbeque tanks.
>
--
Steve Mills
Bath
UK
home e-mail: stevemills@mudslinger.demon.co.uk
work e-mail: stevemills@bathpotters.demon.co.uk
own website: http://www.mudslinger.demon.co.uk
BPS website: http://www.bathpotters.demon.co.uk
Tel: **44 (0)1225 311699
Fax: **44 (0)870 0526466
"My whole being cries out against the inhumanity of regular employment"
(Wilde)
James L Bowen on tue 29 feb 00
-------------------
The usual used price at country auctions around here for 100lb LP tanks is
=2410-=2425. Our supplier usually allows us to use one or two of his for =
free for as
long as we need it. We usually get a day to a day and a half of continuos =
firing
in 24=22X24=22 top hat kiln from one tank full.
Susan Goldstein on wed 1 mar 00
In a message dated 02/29/2000 1:27:56 PM Eastern Standard Time,
nlou@linfield.edu writes:
<< To draw off the propane
as a liquid simply turn the tank upside down. >>
Are you saying that it would be safe to use my small propane tanks upside
down?
Susan
Marcia Selsor on wed 1 mar 00
I always understood that the surface area of the liquid gas is what
determines the abilitiy to release the vapors sufficient for the
consumption of burners.
If the vapors are drawn too quickly by the burners then the tendency for
rapid evaporation (cooling effect) freezes the gas. Most large gas kilns
use 500 to 1000 gallon tanks. I used four tanks in tandem in NY.
Marc Ward has designed a three tank in tandem for two burners my
portable raku kiln.
Marcai in Montana
Paul Lewing wrote:
>
> ----------------------------Original message----------------------------
> I once had a studio partner who, after the water bath didn't work any
> more, would warm the tank up by pulling a burner on a flexible hose out
> of the kiln and pointing it at the tank. This is a good way to make
> yourself eligible for the Darwin Awards. Those are given to people who
> take themselves out of the gene pool in particularly spectacular and
> foolish ways.
> Paul Lewing, Seattle
--
Marcia Selsor
selsor@imt.net
http://www.imt.net/~mjbmls
http://www.imt.net/~mjbmls/spain99.html
http://www.silverhawk.com/ex99/selsor/welcome.html
Kathi LeSueur on wed 1 mar 00
Freezing tanks was a huge problem when I was working in the nursery business
in South Texas. The faster the gas is drawn off the more the tank ices up.
Large users have heaters to combat this problem. But for someone with small
tanks, probably the safest solution is to run water over the tanks with a
hose. Just a small stream should do it.
Kathi LeSueur
Richard Jeffery on thu 2 mar 00
you're going to get a lot of these posts....
DON'T DO THAT!
-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.UKY.EDU]On Behalf
Of Susan Goldstein
Sent: 01 March 2000 17:27
To: CLAYART@LSV.UKY.EDU
Subject: Re: freezing gas tanks
----------------------------Original message----------------------------
In a message dated 02/29/2000 1:27:56 PM Eastern Standard Time,
nlou@linfield.edu writes:
<< To draw off the propane
as a liquid simply turn the tank upside down. >>
Are you saying that it would be safe to use my small propane tanks upside
down?
Susan
John Rodgers on thu 2 mar 00
It's just physics at work. Evaporation is a cooling process. As the liquid
gas evaporates in the tank to it's gaseous state so it can be vented by the
regulator to your burner, the evaporation also drops the temperature. Because
of the nature of the gas used, the pressure it is under, etc, as more propane
is evaporated off, the temperature continues to drop until it is below the
freezing point of the liquid. It is at that point evaporation stops, and your
fire goes out. Running water over the tank will add back sufficient heat to
prevent the further drop of the temperature, keeping it above the freezing
point and therefore liquid so it will continue to evaporate.
John Rodgers
Birmingham, AL
Susan Goldstein wrote:
> ----------------------------Original message----------------------------
> In a message dated 02/29/2000 1:27:56 PM Eastern Standard Time,
> nlou@linfield.edu writes:
>
> << To draw off the propane
> as a liquid simply turn the tank upside down. >>
>
> Are you saying that it would be safe to use my small propane tanks upside
> down?
>
> Susan
Nils Lou on thu 2 mar 00
sure, but to use it as a liquid it must be vaporized so the burner can run
it through the orifice as a gas. Axner sells such a burner for raku. The
burner is designed with an internal chamber where the liquid lpg is
vaporized. No freeze up and you can use every last drop. Nils
On Wed, 1 Mar 2000, Susan Goldstein wrote:
> ----------------------------Original message----------------------------
> In a message dated 02/29/2000 1:27:56 PM Eastern Standard Time,
> nlou@linfield.edu writes:
>
> << To draw off the propane
> as a liquid simply turn the tank upside down. >>
>
> Are you saying that it would be safe to use my small propane tanks upside
> down?
>
> Susan
>
ferenc jakab on thu 2 mar 00
Nils,
You learn something every day. I wish I had known this before I had the 4.5
tonne tank installed.
Feri.
Marc Ward on thu 2 mar 00
I was content to just watch the progress of this thread but, I guess,
it's time to jump in. Many of the things stated here have been true, some has
been conjecture, and some, I believe, ill advised.
Though someone mentioned the chemistry of this, it's actually the physics
of this. Charles' Law of gas physics to be precise. Basically it states that
there is a direct correlation between changes in pressure and temperature.
Quick drops in pressure = a specific drop in temperature... increases in
pressure = a specific increase in temperature. A can of spray paint gets
colder as you release the pressure, a SCUBA tank gets hotter as you fill it
up. If you want the actual formula (it doesn't work well via email), break
out the encyclopedia...
So, what's the answer?; A bigger propane supply. Does water work?;
yes. Do I recommend it?; no.
You are not addressing the problem, you're simply getting around it. That
gets into a matter of personal philosophy about bigger issues than freezing
tanks. I'm not going there....
Many times freezing occurs because of improper burner selection. We make
an 6 cubic foot Raku kiln that gets 10 to 12 firings off of a 20lb barbecue
tank. No freeze up... This is because the burner is designed to deliver the
correct BTU's to a specific size kiln in a given amount of time. Get outside
certain parameters and you begin to have problems. If you are using a system
without a regulator, you will most likely have problems as well as it being
potentially dangerous. If you are using a regulator and having problems, it
can be because of several variables. Kiln size/construction, burner output,
psi range, firing time/tank size, outside temp., ect... But, the bottom line;
you don't have enough gas supply to deal with the burner output.
Now, to the touchy issue....liquid withdrawal. It works. It was designed
for such things as hot air balloons, forklifts, and farm use in Canada. Does
it work for kilns? Sure. So, what's so touchy about that? It was suggested to
turn the tank upside down. DON'T DO IT!!!!!!!!!!!!!
Many burners can handle liquid withdrawal as can many regulators. We sell
regulators that can handle liquid withdrawal. Some burners will. Do you know
which ones you have? Can they deal with liquid? Are they UL listed for
liquid? IF YOU DON'T KNOW, DON'T DO IT!!!! If you're unsure, take your stuff
to a propane supplier and find out. Folks, propane is neat stuff that can be
very useful. It's also dangerous as hell if not used properly.
Use equipment rated for the application
Know the BTU output of your system
Do Not heat tanks with anything that is a potential source of ignition
Use hoses THAT ARE RATED FOR PROPANE!!!
Have fun making pots
Marc Ward
Ward Burner Systems
PO Box 1086
Dandridge, TN 37725
865.397-2914 Voice
865.397-1253 Fax
wardburner@aol.com Email
wardburner.com Online Catalog
Jean Todd on thu 2 mar 00
There is a warning on my LPG tanks saying they must be upright at all times,
Jean in Australia
"Lang may your lum reek"
Des Howard on thu 2 mar 00
Steve
When we had mains water a hose trickling over the 100lb tanks kept
them from freezing. On going bush we had to run 2 banks of 4x100lb
tanks with an automatic changeover regulator that swapped between
banks as the delivered pressure dropped. Now we use a 1/4 tonne tank
that never freezes.
ps the workers at at a busy refilling depot had a nice little scam going,
returned tanks with some propane remaining, say 5 lbs or so, needed
less from the bulk tank to refill, so every 20 or so they had 100lbs spare,
this went, discounted, for cash, to selected customers.
Des
Stephen Mills wrote:
> ----------------------------Original message----------------------------
> We run our gas tanks under a light cold shower when they show signs of
> frosting (no need for hot water, cold is warmer than liquid gas). Means
> we fire 'em right to the end (I do object to giving gas back to the
> company when I've paid for it!).
>
> Steve
> Bath
> UK
>
--
Des & Jan Howard
Lue Pottery
LUE NSW 2850
Australia
Ph/Fax 02 6373 6419
Nils Lou on fri 3 mar 00
You don't explain why not. There is no evidence that it is dangerous.
LPG is at the same pressure whether liquid or vapor. Nils
On Thu, 2 Mar 2000, Richard Jeffery wrote:
> ----------------------------Original message----------------------------
> you're going to get a lot of these posts....
>
> DON'T DO THAT!
>
> -----Original Message-----
> From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.UKY.EDU]On Behalf
> Of Susan Goldstein
> Sent: 01 March 2000 17:27
> To: CLAYART@LSV.UKY.EDU
> Subject: Re: freezing gas tanks
>
>
> ----------------------------Original message----------------------------
> In a message dated 02/29/2000 1:27:56 PM Eastern Standard Time,
> nlou@linfield.edu writes:
>
> << To draw off the propane
> as a liquid simply turn the tank upside down. >>
>
> Are you saying that it would be safe to use my small propane tanks upside
> down?
>
> Susan
>
Nils Lou on fri 3 mar 00
Feri, I know, I went through the multiple tanks all manifolded, water
running thing too. Such a simple solution. Regards, Nils
On Thu, 2 Mar 2000, ferenc jakab wrote:
> ----------------------------Original message----------------------------
> Nils,
> You learn something every day. I wish I had known this before I had the 4.5
> tonne tank installed.
> Feri.
>
Jocelyn Olivia Mc Auley on fri 3 mar 00
On Thu, 2 Mar 2000, Marc Ward wrote:
> colder as you release the pressure, a SCUBA tank gets hotter as you fill it
> up. If you want the actual formula (it doesn't work well via email), break
> out the encyclopedia...
PV=nRT ! Basic physics which you can actually use.
It's amazing how coincidental this list can be. Just yesterday I was
doing a raku fire, and we too had problems losing our pressure with our
tanks freezing up. I actually got to use my science degree pointing out
the magic of this process, and fixing our problem too.
Nice timing. It's great to be on a list so helpful.
Jocelyn McAuley
jmcauley@darkwing.uoregon.edu ><<'>
Marc Ward on fri 3 mar 00
<< There is a warning on my LPG tanks saying they must be upright at all
times, >>
There's a reason for that. Do not turn them upside down unless you know
everthing there is to know. Do you?
While we're still on this subject, John Hesselberth brought it to my
attention that I was implying that freeze-up was soley a function of Charles'
Law of gas physics (pressure/temperature). As was mentioned earlier by Bruce
Girrell, phase change and evaporative cooling also play a leading role in
tank freezeup. Sorry for the confusion...
Marc Ward
Ward Burner Systems
PO Box 1086
Dandridge, TN 37725
865.397-2914 Voice
865.397-1253 Fax
wardburner@aol.com Email
wardburner.com Online Catalog
Kurt Wild on fri 3 mar 00
This is one of those situations where one should listen to known
experts; in particular, the recent post on the subject by Marc Ward. As
Marc has implied, there are some situations where "band aid solutions"
can be very dangerous. Experience has taught me to get good information
from experts in certain instances and then do it right! There are some
situations were experimentation and trial and error are OK but
potentially explosive situations are not the place for guess work or
rumored solutions.
Kurt Wild
1000 E. Cascade Ave.
River Falls, WI 54022
Phone: 715-425-5715
email: kurt.l.wild@uwrf.edu
web site: http://wwwpp.uwrf.edu/~kw77/
cyberscape on fri 3 mar 00
I use a liquid withdrawal system on the tank, a high pressure hose and a
liquid burner. IT ROCKS!!!, and will drain the tank to the bottom
without loss of pressure or freeze up. Liquid withdrawal has been my
choice for 25 years. I have consistently gotten 10-12 hrs of firing
from each 100 lb cylinder in my 22.5" x 27" x 42" raku car kiln, which
I can fire in as little as 5 minutes. Some LP gas dealers call this a
"tar burner", because they use them on the road repair trucks to heat
the tar pots on those -30 days in the far north, when vapor burners and
vapor tanks freeze up. Many dealers in the north will deliver liquid
withdrawal tanks if you request them or will happily set them up for
liquid withdrawal and sell them to you if you ask. In the south they
are less common, but they will still set them up and sell them to you if
requested. You can buy a 500,000 BTU liquid burner that will fire your
kiln superquick, or a 250,000 BTU version which will be quick enough for
most of you. Nils Lou's burner is a version of this burner.
Alternatively, run a cold water from a hose over the tank and valve and
it will keep from freezing up guite so soon, but it is messy, soggy and
still leaves a lot of gas in the tank. When you refill a vapor tank,
you pay for a tank full, including the 15-25% which was already there.
When you refill a liquid withdrawal tank, you refill the whole tank for
the same money. The liquid burner is also a much higher pressure,
shorter flame, which makes the kiln fire more evenly. The only downside
is that it is a bit noisier than a vapor burner.
Harvey Sadow
Theodore Banton on fri 3 mar 00
THe freeze ups are a result of pulling out too many BTU's per hour
(calories). There is no way to prevent this. Pouring warm water over it
just eliminates the condensation on the outside and has no effect to the
propane on the inside that has liquified. The only way to prevent this is by
going to a larger tank and decreasing the psi you are using. Forced air
burners will help with the problem as well
T. Banton
Marc Ward on sat 4 mar 00
In a message dated 3/3/00 12:59:43 PM, nlou@linfield.edu writes:
<< You don't explain why not. There is no evidence that it is dangerous.
LPG is at the same pressure whether liquid or vapor. Nils >>
And what pressure might that be? A full tank in the summer sun is about
200psi. A half empty tank on a really cold winter morning in the NE might
have 20psi. Big difference. Granted a regulator rated for both liquid and
vapor will produce the same outlet pressure, but some folks who should have
regulators don't. Now lets look at another difference...A HUGE difference. A
gallon of liquid propane is 91,690 BTU's. A gallon is physically much smaller
than a cubic foot. A cubic foot of vapor is 2,516 BTU's. This is a huge
difference. If you have liquid as opposed to vapor running through something
and taking up the same volume you have vastly, I mean vastly different BTU
amounts. This is potentially very dangerous if your equipment is not designed
to handle it. Someone earlier mentioned they had turned their tank over and
things got sorta' of freaky and it scaried them. They haven't done it again,
I bet, nor should they. Unless you know exactly what your equipment is
designed and rated for, leave your tank like it was designed to be....right
side up.
Marc Ward
Ward Burner Systems
PO Box 1086
Dandridge, TN 37725
865.397-2914 Voice
865.397-1253 Fax
wardburner@aol.com Email
wardburner.com Online Catalog
Earl Brunner on sat 4 mar 00
So, there is this sky diver falling through the sky on his
way to met the earth and his parachute won't open. He
lookes down and low and behold,
there is this potter zooming upwards into low orbit. (don't
ask how he
knows it's a potter). Anyway, he calles out as they
approach each other. "Hey, do you know any thing about
parachutes?" As the guy wizzes by he
yells back "No, do you know anything about propane tanks?"
Kurt Wild wrote:
>
> ----------------------------Original message----------------------------
> This is one of those situations where one should listen to known
> experts; in particular, the recent post on the subject by Marc Ward. As
> Marc has implied, there are some situations where "band aid solutions"
> can be very dangerous. Experience has taught me to get good information
> from experts in certain instances and then do it right! There are some
> situations were experimentation and trial and error are OK but
> potentially explosive situations are not the place for guess work or
> rumored solutions.
>
> Kurt Wild
> 1000 E. Cascade Ave.
> River Falls, WI 54022
> Phone: 715-425-5715
> email: kurt.l.wild@uwrf.edu
> web site: http://wwwpp.uwrf.edu/~kw77/
--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
Michael Banks on sun 5 mar 00
No Susan, it is not safe to run your propane tanks upside down.
I can't believe the conflicting information being forwarded on this subject.
Would people please not contribute to this unless they have extensive
experience with LPG please?
1. Tanks and bottles should not be used on their side or upside down because
they will "prime", meaning liquid propane/butane can be fed to the regulator
and burners. These are designed to burn vapour only from upright bottles,
which deliver LPG in an expanded, low-density, gas-phase form. If liquid
LPG accidentally gets to the burners, high-density geysers of propane/butane
fluid can squirt from them analogous to water from a garden hose. If this
scenario happens, large volumes of propane can inundate the kiln, volatilise
instantly in the hot enviroment, but because the air/gas ratio is
insufficient to burn this "windfall", volumes of unburnt (but explosive) gas
exit the kiln by all orifices..... Not nice. AVOID PRIMING.
2. As several knowledgible people have noted, freezing-up of bottles/tanks
can be remedied by gentle warming (most safely by water bath or water hose).
This exterior mild heat (relative to the LPG temperature) is conducted
through the steel wall to the liquid propane inside, providing enough extra
energy to allow it to continue to boil into a gas phase, which you need for
your kiln.
As others have noted, LPG needs heat to boil to maintain gas pressure. If
insufficient heat is around to maintain a high enough boiling rate at the
demand rate of the kiln burners, the walls of the bottles/tanks will chill
to a point close to the condensation temperature of propane, boiling will
cease and the kiln may go out. This is a potentially risky situation because
the valves are still open and when the bottles warm up, gas pressures will
rise again and (if the burners are not fitted with safety cut-outs) a rush
of gas can arrive in the flameless kiln. The visible ice on the bottles is
a sure sign that the LPG is needing more heat to continue to volatilise at
the demand rate and the bottle temperature is plummeting. Go out and get
the dog to pee on it. This heat is called the "latent heat of vaporisation"
and is the scientific principle behind the refrigerator.
Michael Banks,
Nelson,
New Zealand
> ----------------------------Original message----------------------------
> You don't explain why not. There is no evidence that it is dangerous.
> LPG is at the same pressure whether liquid or vapor. Nils
>
> On Thu, 2 Mar 2000, Richard Jeffery wrote:
>
> > ----------------------------Original message----------------------------
> > you're going to get a lot of these posts....
> >
> > DON'T DO THAT!
> >
> > -----Original Message-----
> > From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.UKY.EDU]On Behalf
> > Of Susan Goldstein
> > Sent: 01 March 2000 17:27
> > To: CLAYART@LSV.UKY.EDU
> > Subject: Re: freezing gas tanks
> >
> >
> > ----------------------------Original message----------------------------
> > In a message dated 02/29/2000 1:27:56 PM Eastern Standard Time,
> > nlou@linfield.edu writes:
> >
> > << To draw off the propane
> > as a liquid simply turn the tank upside down. >>
> >
> > Are you saying that it would be safe to use my small propane tanks
upside
> > down?
> >
> > Susan
> >
>
Nils Lou on mon 6 mar 00
yes, Susan, It is safe to run your propane tanks upside down
Turn those propane tanks upside down-- BUT, I also said you need
an appropriate burner, one which is designed for liquid withdrawal.
On threads like this a lot of misinformation gets bandied around
with scare words mixed with scientific sounding background about Btus in
liquid versus vapor and manufacturers labels and so forth to give credence
to the writers admonition.
Many, many potters have experienced freeze-up (a misnomer) by
drawing off vapor faster than it can boil off. As many have said, the tank
is too small for the use; get a larger tank is one answer. Putting the
tank in a tub of water is another that has worked for some because it
does add some heat calories and extends the vaporization to a small
degree--maybe enouigh to finish the firing, but it is an awkward solution.
Running water does the same thing, but leaves a mess and requires a water
source. Multiple tanks hooked up together helps, but is not very portable.
To those who have rejected my inverted tank suggestion it seems
most have assumed I meant it would solve the problem with a VAPOR burner.
My fault for not being clear enough. With a burner designed to work with
liquid withdrawal ONE WAY to get liquid is to turn the tank upside down.
Another is to have a dip tube valve designed to draw off liquid. It is
COMMONLY DONE and is as safe as drawing off vapor. A dip tube is simply a
tube inside th tank that reaches to the bottom of the tank so all the LPG
can be used with NO significant reduction of pressure. I have taken the
vapor valve off of a standard 20 pound tank, threaded the intake which is
the size of a 1/4 inch pipe, added an appropriate length of 1/4 inch pipe
and re installed it.
A burner designed for liquid is simply double walled so the barrel
is a chamber where the liquid can be vaporized before being injected
through the spud (orifice). It costs a little more than a simple vapor
burner which is essentially a specially sized tube.
Two things are needed for liquid withdrawal. The burner as I have
decribed and a regulator designed to handle LPG in liquid/vapor form. I
have designed such a burner/ regulator combination specifically for raku
potters using the small tanks and I gave the design rights to Howard
Axner. They are fabricated for him by the same manufacturer in Michigan
who produces my MFT burners. I have NO financial interest or arrangement
with Axner concerning these burners. I believe they are the best solution
and I wanted them to be available. They are constructed in stainless
steel, and with this setup a five gallon tank can be totally used with NO
freeze-up; to the last drop of LPG. Ideally, I recommend using a tank
fitted with a liquid withdrawal valve, i.e., one with a dip tube. Most LPG
dealers can supply. However, it is safe to simply turn a tank upside down
to draw off the LPG in liquid form. It has to be properly supported so the
regulator is not in the way. In either case it is necessary to have the
liquid withdrawal regulator as a vapor regulator wont work properly. I
think if you add up the lost propane not used in small tanks, the
inconvenience of having the burner lose pressure the cost of equipment
designed to prevent all that is small. And, if you desire portability,
the small tank is perfect. Multiple tanks manifolded together with TEE
assemblies are a viable solution, but not for the raku potter who gives
workshops or moves around to a variety of places.
For many years Japanese potters have used liquid withdrawal LPG
with the use of vaporizers costing about $700. I have gradually introduced
the idea of self vaporizing liquid withdrawal burners to a number of
Japanese potters thus eliminating the expensive vaporizers. They are
gradually catching on in Japan.
Except in the northern tier of states and Canada vapor burners for
LPG can work well providing the tank is large enough to keep vapor
pressure. In some places this means a 1000 gallon tank or larger. In St
Paul, Minnesota (1962-67) before I developed a liquid withdrawal burner
suitable for firing a large kiln to stoneware temps. My partner Eugene
Johnson and I had eight 100 pound tanks manifolded together in an
enclosure outside the studio (garage) and adjacent to the studio. It was
just on the other side of the wall from the kiln. When the kiln was firing
we blower/vented hot air from the studio out to the tank enclosure to warm
the tanks. Each tank held approximately 26 gallons of LPG. In an urban
area it was OK to use small tanks, but larger ones had to be ten feet or
more from any building. That was a workable solution for that time. Later,
the liquid withdrawal burner made life a lot easier.
I hope this provides useful information and clears up some of the
questions raised. If you dont feel it is safe to turn a tank over, dont do
it. Nils Lou
PS. Michael Banks admonitions starting with #1 I agree with
On Sun, 5 Mar 2000, Michael Banks wrote:
> ----------------------------Original message----------------------------
> No Susan, it is not safe to run your propane tanks upside down.
>
> I can't believe the conflicting information being forwarded on this subject.
> Would people please not contribute to this unless they have extensive
> experience with LPG please?
>
> 1. Tanks and bottles should not be used on their side or upside down because
> they will "prime", meaning liquid propane/butane can be fed to the regulator
> and burners. These are designed to burn vapour only from upright bottles,
> which deliver LPG in an expanded, low-density, gas-phase form. If liquid
> LPG accidentally gets to the burners, high-density geysers of propane/butane
> fluid can squirt from them analogous to water from a garden hose. If this
> scenario happens, large volumes of propane can inundate the kiln, volatilise
> instantly in the hot enviroment, but because the air/gas ratio is
> insufficient to burn this "windfall", volumes of unburnt (but explosive) gas
> exit the kiln by all orifices..... Not nice. AVOID PRIMING.
>
> 2. As several knowledgible people have noted, freezing-up of bottles/tanks
> can be remedied by gentle warming (most safely by water bath or water hose).
> This exterior mild heat (relative to the LPG temperature) is conducted
> through the steel wall to the liquid propane inside, providing enough extra
> energy to allow it to continue to boil into a gas phase, which you need for
> your kiln.
>
> As others have noted, LPG needs heat to boil to maintain gas pressure. If
> insufficient heat is around to maintain a high enough boiling rate at the
> demand rate of the kiln burners, the walls of the bottles/tanks will chill
> to a point close to the condensation temperature of propane, boiling will
> cease and the kiln may go out. This is a potentially risky situation because
> the valves are still open and when the bottles warm up, gas pressures will
> rise again and (if the burners are not fitted with safety cut-outs) a rush
> of gas can arrive in the flameless kiln. The visible ice on the bottles is
> a sure sign that the LPG is needing more heat to continue to volatilise at
> the demand rate and the bottle temperature is plummeting. Go out and get
> the dog to pee on it. This heat is called the "latent heat of vaporisation"
> and is the scientific principle behind the refrigerator.
>
> Michael Banks,
> Nelson,
> New Zealand
>
> > ----------------------------Original message----------------------------
> > You don't explain why not. There is no evidence that it is dangerous.
> > LPG is at the same pressure whether liquid or vapor. Nils
> >
> > On Thu, 2 Mar 2000, Richard Jeffery wrote:
> >
> > > ----------------------------Original message----------------------------
> > > you're going to get a lot of these posts....
> > >
> > > DON'T DO THAT!
> > >
> > > -----Original Message-----
> > > From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.UKY.EDU]On Behalf
> > > Of Susan Goldstein
> > > Sent: 01 March 2000 17:27
> > > To: CLAYART@LSV.UKY.EDU
> > > Subject: Re: freezing gas tanks
> > >
> > >
> > > ----------------------------Original message----------------------------
> > > In a message dated 02/29/2000 1:27:56 PM Eastern Standard Time,
> > > nlou@linfield.edu writes:
> > >
> > > << To draw off the propane
> > > as a liquid simply turn the tank upside down. >>
> > >
> > > Are you saying that it would be safe to use my small propane tanks
> upside
> > > down?
> > >
> > > Susan
> > >
> >
>
ferenc jakab on mon 6 mar 00
Having read Michael Banks' well written and lucid contribution on this
subject, and in defence of Nils Lou, Nils did state that liquid draw off
must be accompanied by the appropriate liquid draw off burner. That cannot
be over stated.
Feri.
Michael Banks on mon 6 mar 00
Nils,
Thank you for your comments. You are obviously not in the group of
commentators sans experience! I wished (dogmatically) to underline the
warning to our majority subscribers -assuming that people with the more
expensive and large-scale commercial liquid plumbing, would not need this
kind of advice. It is the large numbers of raku drum-kiln and other small
kiln users that worried me. I think that most people with small to medium
sized bottles, like Susan are using vapour burners. Perhaps Susan can
enlighten us regarding her set-up?
The fact remains, delivering liquid propane to a vapour burner can result in
a massive increase in energy. Which is the reason for the warning signs
stuck to gas bottles and my admonition. Liquid propane geysering from
vapour burners in a lit kiln can surely be regarded as a life/property
threatening situation.
We must also bear in mind that only a minority of potters live in the cold
(rich) northern countries. Currently, New Zealand and Australian kiln
manufacturers are heavily exporting to South East Asia because of bans there
on the use of rain-forest wood fuel. The vast majority of these are LPG
with vapour burners. Thailand, Vietnam & Indonesia together have a larger
population than North America, with significantly more potters. How many
are on the list? Maybe not too many at present, but we may find that they
represent the tip of a very large network. We have a responsibility to
consider that many potters using LPG in the world today can only afford the
most basic set-ups. These mostly do not include expensive vaporisers,
stainless steel liquid feed burners etc. The ones I see in the field usually
have burners, manifolds etc, made from water pipe.
Not mentioned so far, is the effect of the dew point on over-cooling of gas
bottles and the insulating power of ice. For years I fired 20 and 30 cu
foot LPG kilns on single and double 45kg bottles. Ice formed on the bottles
during glost firings in cool weather, but not necessarily on the coldest
days, but often on the humid ones. I put this down to the high dew point on
those days. Once ice forms, further chilling proceeds more quickly because
the frost layer insulates the steel from convecting (and warming) air. I
found that keeping a trickle hose on the bottles was sufficient to keep the
ice off and the gas pressure high enough. So using a water hose is not just
to provide thermal energy to the gas, but to remove the ice, which is a poor
conductor.
Michael Banks,
Nelson,
New Zealand
> yes, Susan, It is safe to run your propane tanks upside down
> Turn those propane tanks upside down-- BUT, I also said you need
> an appropriate burner, one which is designed for liquid withdrawal.
> On threads like this a lot of misinformation gets bandied around
> with scare words mixed with scientific sounding background about Btus in
> liquid versus vapor and manufacturers labels and so forth to give credence
> to the writers admonition.
> Many, many potters have experienced freeze-up (a misnomer) by
> drawing off vapor faster than it can boil off. As many have said, the tank
> is too small for the use; get a larger tank is one answer. Putting the
> tank in a tub of water is another that has worked for some because it
> does add some heat calories and extends the vaporization to a small
> degree--maybe enouigh to finish the firing, but it is an awkward solution.
> Running water does the same thing, but leaves a mess and requires a water
> source. Multiple tanks hooked up together helps, but is not very portable.
> To those who have rejected my inverted tank suggestion it seems
> most have assumed I meant it would solve the problem with a VAPOR burner.
> My fault for not being clear enough. With a burner designed to work with
> liquid withdrawal ONE WAY to get liquid is to turn the tank upside down.
> Another is to have a dip tube valve designed to draw off liquid. It is
> COMMONLY DONE and is as safe as drawing off vapor. A dip tube is simply a
> tube inside th tank that reaches to the bottom of the tank so all the LPG
> can be used with NO significant reduction of pressure. I have taken the
> vapor valve off of a standard 20 pound tank, threaded the intake which is
> the size of a 1/4 inch pipe, added an appropriate length of 1/4 inch pipe
> and re installed it.
> A burner designed for liquid is simply double walled so the barrel
> is a chamber where the liquid can be vaporized before being injected
> through the spud (orifice). It costs a little more than a simple vapor
> burner which is essentially a specially sized tube.
> Two things are needed for liquid withdrawal. The burner as I have
> decribed and a regulator designed to handle LPG in liquid/vapor form. I
> have designed such a burner/ regulator combination specifically for raku
> potters using the small tanks and I gave the design rights to Howard
> Axner. They are fabricated for him by the same manufacturer in Michigan
> who produces my MFT burners. I have NO financial interest or arrangement
> with Axner concerning these burners. I believe they are the best solution
> and I wanted them to be available. They are constructed in stainless
> steel, and with this setup a five gallon tank can be totally used with NO
> freeze-up; to the last drop of LPG. Ideally, I recommend using a tank
> fitted with a liquid withdrawal valve, i.e., one with a dip tube. Most LPG
> dealers can supply. However, it is safe to simply turn a tank upside down
> to draw off the LPG in liquid form. It has to be properly supported so the
> regulator is not in the way. In either case it is necessary to have the
> liquid withdrawal regulator as a vapor regulator wont work properly. I
> think if you add up the lost propane not used in small tanks, the
> inconvenience of having the burner lose pressure the cost of equipment
> designed to prevent all that is small. And, if you desire portability,
> the small tank is perfect. Multiple tanks manifolded together with TEE
> assemblies are a viable solution, but not for the raku potter who gives
> workshops or moves around to a variety of places.
> For many years Japanese potters have used liquid withdrawal LPG
> with the use of vaporizers costing about $700. I have gradually introduced
> the idea of self vaporizing liquid withdrawal burners to a number of
> Japanese potters thus eliminating the expensive vaporizers. They are
> gradually catching on in Japan.
> Except in the northern tier of states and Canada vapor burners for
> LPG can work well providing the tank is large enough to keep vapor
> pressure. In some places this means a 1000 gallon tank or larger. In St
> Paul, Minnesota (1962-67) before I developed a liquid withdrawal burner
> suitable for firing a large kiln to stoneware temps. My partner Eugene
> Johnson and I had eight 100 pound tanks manifolded together in an
> enclosure outside the studio (garage) and adjacent to the studio. It was
> just on the other side of the wall from the kiln. When the kiln was firing
> we blower/vented hot air from the studio out to the tank enclosure to warm
> the tanks. Each tank held approximately 26 gallons of LPG. In an urban
> area it was OK to use small tanks, but larger ones had to be ten feet or
> more from any building. That was a workable solution for that time. Later,
> the liquid withdrawal burner made life a lot easier.
> I hope this provides useful information and clears up some of the
> questions raised. If you dont feel it is safe to turn a tank over, dont do
> it. Nils Lou
> PS. Michael Banks admonitions starting with #1 I agree with
>
>
> On Sun, 5 Mar 2000, Michael Banks wrote:
>
> > ----------------------------Original message----------------------------
> > No Susan, it is not safe to run your propane tanks upside down.
> >
> > I can't believe the conflicting information being forwarded on this
subject.
> > Would people please not contribute to this unless they have extensive
> > experience with LPG please?
> >
> > 1. Tanks and bottles should not be used on their side or upside down
because
> > they will "prime", meaning liquid propane/butane can be fed to the
regulator
> > and burners. These are designed to burn vapour only from upright
bottles,
> > which deliver LPG in an expanded, low-density, gas-phase form. If
liquid
> > LPG accidentally gets to the burners, high-density geysers of
propane/butane
> > fluid can squirt from them analogous to water from a garden hose. If
this
> > scenario happens, large volumes of propane can inundate the kiln,
volatilise
> > instantly in the hot enviroment, but because the air/gas ratio is
> > insufficient to burn this "windfall", volumes of unburnt (but explosive)
gas
> > exit the kiln by all orifices..... Not nice. AVOID PRIMING.
> >
> > 2. As several knowledgible people have noted, freezing-up of
bottles/tanks
> > can be remedied by gentle warming (most safely by water bath or water
hose).
> > This exterior mild heat (relative to the LPG temperature) is conducted
> > through the steel wall to the liquid propane inside, providing enough
extra
> > energy to allow it to continue to boil into a gas phase, which you need
for
> > your kiln.
> >
> > As others have noted, LPG needs heat to boil to maintain gas pressure.
If
> > insufficient heat is around to maintain a high enough boiling rate at
the
> > demand rate of the kiln burners, the walls of the bottles/tanks will
chill
> > to a point close to the condensation temperature of propane, boiling
will
> > cease and the kiln may go out. This is a potentially risky situation
because
> > the valves are still open and when the bottles warm up, gas pressures
will
> > rise again and (if the burners are not fitted with safety cut-outs) a
rush
> > of gas can arrive in the flameless kiln. The visible ice on the bottles
is
> > a sure sign that the LPG is needing more heat to continue to volatilise
at
> > the demand rate and the bottle temperature is plummeting. Go out and
get
> > the dog to pee on it. This heat is called the "latent heat of
vaporisation"
> > and is the scientific principle behind the refrigerator.
> >
> > Michael Banks,
> > Nelson,
> > New Zealand
> >
> > > ----------------------------Original
message----------------------------
> > > You don't explain why not. There is no evidence that it is dangerous.
> > > LPG is at the same pressure whether liquid or vapor. Nils
> > >
> > > On Thu, 2 Mar 2000, Richard Jeffery wrote:
> > >
> > > > ----------------------------Original
message----------------------------
> > > > you're going to get a lot of these posts....
> > > >
> > > > DON'T DO THAT!
> > > >
> > > > -----Original Message-----
> > > > From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.UKY.EDU]On
Behalf
> > > > Of Susan Goldstein
> > > > Sent: 01 March 2000 17:27
> > > > To: CLAYART@LSV.UKY.EDU
> > > > Subject: Re: freezing gas tanks
> > > >
> > > >
> > > > ----------------------------Original
message----------------------------
> > > > In a message dated 02/29/2000 1:27:56 PM Eastern Standard Time,
> > > > nlou@linfield.edu writes:
> > > >
> > > > << To draw off the propane
> > > > as a liquid simply turn the tank upside down. >>
> > > >
> > > > Are you saying that it would be safe to use my small propane tanks
> > upside
> > > > down?
> > > >
> > > > Susan
> > > >
> > >
> >
>
>
Ray Aldridge on tue 7 mar 00
At 06:12 PM 3/3/00 EST, you wrote:
>----------------------------Original message----------------------------
>THe freeze ups are a result of pulling out too many BTU's per hour
>(calories). There is no way to prevent this. Pouring warm water over it
>just eliminates the condensation on the outside and has no effect to the
>propane on the inside that has liquified.
I'm sorry, but this is incorrect, as any potter who's fired extensively
with propane can testify. Granted that water is a temporary solution, it
still is useful to know that if a tank starts to freeze up as you approach
the end of a firing, you can often keep it going with a water hose long
enough to complete the firing.
Ray
Aldridge Porcelain and Stoneware
http://www.goodpots.com
Marc Ward on tue 7 mar 00
In a message dated 3/6/00 1:51:56 PM, nlou@linfield.edu writes:
<< On threads like this a lot of misinformation gets bandied around
with scare words mixed with scientific sounding background about Btus in
liquid versus vapor and manufacturers labels and so forth to give credence
to the writers admonition. >>
I'll accept all that....just drop the words "sounding" and "misinformation".
Those are very "loaded" and prejudicial terms that imply they have no basis
in fact. Are you disputing the BTU figures I gave and their ramifications if
a vapor burner primes and injects liquid into a kiln? I wouldn't go
there......
Marc Ward
Ward Burner Systems
PO Box 1086
Dandridge, TN 37725
865.397-2914 Voice
865.397-1253 Fax
wardburner@aol.com Email
wardburner.com Online Catalog
| |
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