Hello All
I am in the uk and am thinking about making a small homemade furnace
using calor gas as
a fuel ,I have seen many designs for these on the net on US sites
using propane as a fuel with venturi type burners.
Am I right in thinking that in the UK the normal calor gas regulator
is a low pressure fixed 25mbar type so that there would not be enough
gas pressure to operate a non forced air type of burner efficiently as
is seen on some of the US sites.
How have other UK Hobby Casters dealt with this has any one produced a
small furnace using calor gas successfully or have other UK hobby
casters gone down the waste oil and forced air route. ?
Regards
Ron Priest
You might want to look at the recent/last copy of "model engineer" as
there is an article about a home cast iron melting furnace running on
gas. I am not looking at casting but glassblowing and have a 47kg Calor
propane bottle, I know one can take at least 2.5 bar off these with
appropriate regulators and so easily use non forced air burners although
I am planning to use forced air for better mixture control. I do know a
number of people that have used and are using either propane or LPG with
non forced air systems using amal burners which are similar to some
units such as Reil burners.
r>Hello All
Yes OK David
47Kg is a bit of a whopper the standard 15Kg I normally get from a
local shop just round the corner ,I use these in the heater in the
garage here and wanted to keep to this convienient size (its heavy
enough for me ) :-)
Yes of course 2.5 Bar is about 36 PSI and from what ive read you
would need somewhere around 15 to 20 PSI for a non assisted burner
So as you say with a high pressure regulator there should be no
problem.
The regulator on the 15Kg size is only 25 mBar (millibar) so I think I
am gonna
have to make up a blower to assist.
I am not familiar with "model engineer" is that a UK publication ? I am
not into model
engineering myself.
I got into wanting to cast metal by building a small homemade cnc
milling machine
on which i do engraving , which required some parts to be cast
,originally I did the melting in a small 1200 degree kiln however a
couple of weeks ago the nichrome heating elements in the kiln burned
out so I want to build myself a small furnace cheaply to take its
place.
I intend to use a 15Kg calor gas bottle as a skin ,I am sure you have
seen the sort of thing I mean.I have allready cut the bottle down to
size and wanted to make the burner next before i lash out on the
castable refractory.
Yesterday I made up a quick prototype burner something like from the
photographs on
formatting link
It was then I realized that the gas pressure on the 15Kg calor was
restricted to 25mbar
and so this type of burner would not work and I would need a blower.
Regards Ron Priest
I
David Bill> You might want to look at the recent/last copy of "model engineer" as
The 47kg is the largest portable I am aware of and the glassblowing
gloryhole has a huge demand for gas, depending on temperature I may have
to gang them to get the gas volume required at full chat but then it may
be outputing 40kw+. See
formatting link
and
formatting link
. You
should be able to get 2.5 bar from the smaller bottle but with reduced
volume, its about heat input into the bottle and how much gas you can
evaporate if your use is continuously. All the bottles as far as I am
aware have the same fitting so the kg of gas you can draw per hour is
limited by bottle size and temperature.
"Model Engineer" is a popular UK publication, I don't subscribe but a
couple of neighbours do, see
formatting link
, should
be easy to find at a good news agent in the UK.
Re your nichrome elements I hope 1200F was what you intended as 1200C
would be above the recommended for nichrome, you should change to such
as Kanthal A1 or equivalent, FeCrAl type element providing the
refractory is upto it.
For refractory products I have dealt with Wright Refractories in
Wordsley, Stourbridge. Prices seem good and Stuart Wright is
knowledgable and friendly. Lots of glass people I know have recommended
them to me. Depending on your location in the UK you may want to pick up
the stuff yourself, I find as I am fairly close that for lower volumes
as I use its cheaper to pop up and collect the stuff than have it
shipped but it depends on the value of your time and how much you have.
r>Yes OK David
Go to your local gas supplier (Calor are not always the cheapest) and get an
adjustable propane regulator. IIRC mine goes up to 45psi or so.
Mark Rand
RTFM
I just went looking at the Calor.co.uk site, and they have these odd
Blue and Green "Patio Gas" and "BBQ Gas" Butane bottles with an
oddball Quick Connect regulator - Is this what you want to use?
I didn't realize they even used Butane for more than the old
"Camping Gaz" disposable cylinders - Over here, all they sell it for
is refilling cigarette lighters...
You really do need the larger 100-pound (47kg) Orange Propane bottle
- or multiple small bottles on a common manifold - when using a high
rate of LPG gas for a large furnace or kiln burner.
If you are taking the gas from a normal size Propane barbecue
bottle, the liquefied gas has to boil to vapor inside the bottle,
which requires a heat input, and the outside air can only supply that
heat at a restricted rate through the steel. Draw off the gas too
fast and the bottle gets cold from the effect of the vaporization, the
pressure inside the bottle drops way off, and your burner goes out.
You can get around this by putting the Propane bottle in a bucket of
hot water - but then you have to keep the water hot, and not too hot
and overheat the cylinder to where the safety valve pops off...
They make higher pressure regulators - start scrounging.
If you still want to use the small Propane bottles you will need to
make a manifold to get the necessary flow rate. Use a tee or cross
fitting and two or three high-pressure flexible propane hoses with POL
male fittings for the bottles, and the tee connects to the input of
the 2.5 Bar regulator - the Calor dealer can set this up for you.
If you put check-valves on the bottle hoses, you can even change out
an empty bottle while the burner keeps running on the others.
Or hire a larger permanent site tank, then you don't have to
transport it anywhere for filling - they send the delivery truck out
to you at about the same fuel price. (*)
(* - For fuel on their normal delivery route schedule - in the USA
there is an extra charge for sending the truck out for "emergencies",
and more for nights/weekends/holidays. In other words, get a big
enough tank.)
The big tanks have a high enough draw rate that you can run a foundry
burner all day. The 300-gallon / 1200L size would be plenty.
Hello David
I am very impressed with your website and the "glory hole" furnace as
you call it ,
your gallery of is most impressive I can see you are pretty much an
expert
It must be very satisfing to be able to create such fine works.
Yes I can certainly see why you need the 47Kg fuel supply.
The Kiln I used to use was salvaged from a Skip at the University where
I work
I am an electronics technician at Coventry University and the kiln used
to be used
for research into ceramic hybrid circuits a line of research that has
now been discontinued it had a Cal digital controller with a max
temperature of 1200 degrees Celcius.
I used it about 2 dozen times to melt aluminium in an A4 salamander but
it finally
burned out I stripped the thing down and the element wire was complely
brittle and literally fell apart in my hands I am only assuming the
element was nichrome it may
well have been made of something else but its years of use and rough
treatment by me
in melting aluminium killed it in the end.
Thankyou for the information on Model Engineer and on Refractory
Suppliers
I cant find a web site for Wright Refractories so cant look up the
prices
but have had some quotes for refractory as much as £63 per 26Kg bag
for 1800C
Refractory you certainly have to shop around for this stuff.
I am in Coventry so Birmingham is not that far to go ,perhaps you could
give me some idea of their prices.
Regards
Ron Priest
David Bill> The 47kg is the largest portable I am aware of and the glassblowing
Hi Bruce
Thanks for your reply
In the UK lots of people use a small heater called a "Super Sir" these
run on 15Kg
Butane cylinders and are fitted with a low pressure 25mbar regulator as
standard
they are very popular here for use in the winter months I used mine
hell of a lot this winter,which seemed to last forever.
The 15Kg bottle of gas costs around =A313 ie 26 USD and this includes
delivery if you get the gas from a local supplier ,if you buy direct
from Calor it costs a lot more ie =A320
The Blue 15Kg Bottle is very,very common here in the UK most small
hardware shops will stock only this size.
I take your point about higher pressure regulators and multiple
manifolds
and I can see the physics involved .Using gas is just one idea of
fueling a small furnace
I am sure you have seen small furnaces that run on waste cooking oil as
well and perhaps i should investigate this also,I am only in the
planning stages of making a small furnace at the moment and trying to
do as much research on this as I can.
Since its only a hobby persuit I have to keep the costs down as much as
possible.
Best Regards
Ron Priest
Its Now pretty obvious to me that using calor gas is just not on as a
fuel for a small furnace
The gas pressure is just not hight enough and ajustable regulators are
not available for calor.
Propane is the answer but is more expensive than calor
ajustable regulators are available for propane cheaply from ebay.
I would like to thankyou all for your input on this
Best Regards
Ron Priest
Ron,
Thank you for the compliment about the glassblowing, been doing
it about 6.5 years now as a hobby and getting better all the time. I
must add some recent items to the gallery.
Regarding your kiln if it went to 1200C then I would expect Kanthal A1
FeCrAl elements or equivalent. They don't last forever and become
brittle once fired so your use for melting Al may not have been
responsible for the failure and handling them once used is likely to
lead to breakage. I know you can damage exposed elements due to metal
vapours/grease/carbon contaminating them but as Al is the main
protective element in FeCrAl elements I not sure what effect it would
have. I have contact details for a chap that sells element wire if you
need it I can dig it out.
Wrights do have a website, well sort of, its under construction
formatting link
. Your best bet is to give them a ring on 01384
76493 and ask for a current price list, tell them what you want and they
should be able to give you the details. I have the "potters and glass
makers price list" which is a couple of pages. They sell a number of
products from Thermal Ceramics such as VFB vacuum formed board, IFB
insulating fire brick, Harbison-Walker Refractories such as castables.
Some fairly recent prices
Wrightcast 1600 BK castable £12.17 per 25kg bag. This is a
Harbison-Walker product and comes under various name such as AP Green
Mizzou. Good to 1650C.
1400 insulating castable £13.90 per 25kg. Good to 1400C.
Ceraboard 100 25 x 1000 x 1200 £35.31 per board.
Thermal Ceramics JM23 IFB 230 x 114 x 76 £1.05 each box 20.
Add VAT to those. Wright get a lot of things if you request it and keep
stock of common stuff such as the 1600 BK, IFB, VFB but check stock with
them first.
I can understand 1800C castable being expensive and over the top for a
casting furnace I think. I do have some castable alumina and it was
rather expensive.
Regarding one of your other threads I think you need to be careful what
you refer to as Calor gas, I have Calor propane but they do do other gas
mixes. I do now know of a cheaper source for propane so shall try them
when the current bottle runs out.
Cheers
Dave
r>Hello David
Ron,
Forgot to mention in my other reply. When you get the castable ask
the supplier for the recommended water mix ratio. This will be for
vibratory casting and makes it hard work to mix. You can add a little
more water but too much and you can easily get major seperation of the
solids and cement binder leading to a poorer item. I recently made a
small vabratory casting table and it transforms the castable from a
thick stodge to a thick fluid which flows into the forms. I have also
used a needle scaler on the back of a wood block to vibrate the mix
locally to similar effect. I expect you can rent concrete vibrators from
a hire shop if you were doing something big enough to warrant it.
r>Hello David
Small world.. I'm in Rugby :-) Lots of useful names and addresses from David.
I suspect that I may be following some of them up as well.
Regards
Mark Rand
Yes Mark
As you say Small World David has been so very helpfull with local
practical information
and may I say that it has been a pleasure to chat with you all on this
thread I will be off on holiday to greece shortly and will not be doing
anything about starting this small furnace project untill I get back
but I now have all the information I need to turn the Idea into reality
thanks to this Group.
Best Regards
Ron Priest
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