HomeRoast Digest


Topic: probat 5 kilo roasters (19 msgs / 418 lines)
1) From: Tom & Maria - Sweet Maria's Coffee
fairly rare to see these on ebay, let alone 2 at one time. the one in 
Utah looks a lot cleaner, while the one in ohio looks like it has 
been abused (despite the description about how it was custom 
outfitted for a prbat retiree.) with cleaning, it will be fine. 5 k 
machines are in big demand.
tom
--
                   "Great coffee comes from tiny roasters"
            Sweet Maria's Home Coffee Roasting  -  Tom & Maria
                      http://www.sweetmarias.com                Thompson Owen george_at_sweetmarias.com
     Sweet Maria's Coffee - 1115 21st Street, Oakland, CA 94607 - USA
             phone/fax: 888 876 5917 - tom_at_sweetmarias.com

2) From: Alchemist John
Wow, almost makes me want to snag that one in Utah.  I bet I could do 
20 lbs of cocoa in it.  And I love the cast iron drum.  So, what does 
it take to convert to propane?....
At 08:49 11/3/2007, you wrote:
<Snip>
John Nanci
AlChemist at large
Zen Roasting , Blending & Espresso pulling by Gestalthttp://www.chocolatealchemy.com/

3) From: Rich
Change the regulator, if there is one and change the gas jets.  Easy 
conversion.
Alchemist John wrote:
<Snip>

4) From: Alchemist John
I have often wondered about that.  Why is there different regulators 
and jets needed?  Do you know the specifics of "why"?  Does one need 
outside oxygen and the other doesn't?
Have you actually done a conversion?
At 10:39 11/3/2007, you wrote:
<Snip>
John Nanci
AlChemist at large
Zen Roasting , Blending & Espresso pulling by Gestalthttp://www.chocolatealchemy.com/

5) From: Rich
Propane operates at 11" wc pressure and a different fuel / air mixture 
ratio than natural gas.  Natural gas is usually at 5" wc.  So, that is 
why the regulator change out.  And natural gas and propane are different 
sized molecules and the different fuel / air requirements require the 
jet size change when changing fuel.  Most appliance manufactures will 
provide a conversion kit and instructions for changing fuel from natural 
gas to propane.
As you would suspect, there are liability "issues" with these 
conversions so finding the local HVAC shop that will make the change 
over can be difficult.  In most parts of the country the bulk propane 
supplier will do this kind of work.
Alchemist John wrote:
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6) From: Michael Dhabolt
John,
Different air to fuel mixes for efficient combustion.  No - re:
Oxygen.....just fuel mix with ambient air for both. Yes, I've done
conversions ..... not on coffee roaster though ... commercial gas
fired range .... conversion kit including different jets were
available from the mfg. ..... simple.
Mike (just plain)

7) From: raymanowen
"...what does it take to convert to propane?...."
A supply of Propane gas.
There is more heat energy in a given volume of propane gas than there is in
the same volume of natural gas, at the same pressure.
Without changing the orifice or "jet" size in the single barrel carburetor
that is part of the burner assembly, the propane air/fuel ratio would be too
"rich-" too many molecules of fuel for the available oxygen molecules.
It's a much bigger hassle to modify the existing air inlet and venturi to
increase the air flow than to throttle the fuel stream.
Cheers, Mabuhay -RayO, aka Opa!
Roast on!
On 11/3/07, Alchemist John  wrote:
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8) From: Jim Gundlach
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John,
      With a single burner at 48,000 btu you would want to install an  
orifice drilled with a size 63 bit.  More than likely you would need  
to buy a 72 and get a bit and drill it out.
      Pecan Jim
On Nov 3, 2007, at 11:45 AM, Alchemist John wrote:
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John,     =
With a single burner at 48,000 btu you would want to install an orifice =
drilled with a size 63 bit.  More than likely you would need to buy =
a 72 and get a bit and drill it out.     Pecan =
Jim
On Nov 3, 2007, at 11:45 AM, Alchemist John =
wrote:
Wow, almost makes me want to snag that one in = Utah.  I bet I could do 20 lbs of cocoa in it.  And I love the = cast iron drum.  So, what does it take to convert to = propane?.... At 08:49 11/3/2007, you wrote: fairly rare to see these on ebay, = let alone 2 at one time. the one in Utah looks a lot cleaner, while the = one in ohio looks like it has been abused (despite the description about = how it was custom outfitted for a prbat retiree.) with cleaning, it will = be fine. 5 k machines are in big demand. tom -- == __ =             &n= bsp;     "Great coffee comes from tiny roasters" =            Sweet = Maria's Home Coffee Roasting  -  Tom & Maria =             &n= bsp;         =http://www.sweetmarias.com =             &n= bsp;  Thompson Owen george_at_sweetmarias.com == __     Sweet Maria's Coffee - 1115 21st Street, = Oakland, CA 94607 - USA =             = phone/fax: 888 876 5917 - tom_at_sweetmarias.com = homeroast mailing = list =http://lists.sweetmarias.com/mailman/listinfo/homeroast To = change your personal list settings (digest options, vacations, = unsvbscribes) go to =http://sweetmarias.com/maillistinfo.html#personalsettings =

= John Nanci AlChemist at large Zen Roasting = , Blending & Espresso pulling by Gestalt =http://www.chocolatealchemy.com/ =

= = --Apple-Mail-37--1056599957--

9) From: Rich
Best approach is to pull the natural gas orifice(s) and measure them, 
there is a conversion chart.  Does this roaster only have one burner? 
Most burners run 20 to 25K each, give or take for a practical size. 
Also, Probat most likely sells the propane orifice.  That will be an 11" 
gas inlet pressure orifice. Also so make sure that your new propane 
supply is regulated to 11" to 13" wc or...
Jim Gundlach wrote:
<Snip>

10) From: Mike Chester
This is a multi-part message in MIME format.http://www.grillparts.com/howto/conversion.htmThis site is intended for users of gas grills, but it has a lot of =
information about converting gas types, including charts of orifice =
sizes.  Hope that this helps.
Mike Chester

11) From: John Brown
ng goes by inches of water column pressure  lp goes by pounds per  
square inch pressure.  water column is 28 inches to one PSI.  that is if 
i remember right.  normal natural gas pressure at ones home is 12 to 14 
inches of Water column.  big difference.  different regulator and jet 
size is much smaller.
Alchemist John wrote:
<Snip>

12) From: Rich
Propane is regulated to 11" to 13" max to a home.  Some BBQ grills 
operate at 2 pounds.  This is NFPA regulations and not just a whim.  If 
you have an appliance operating at a higher pressure you are on your own 
and it would not be a good idea to let the world know.
John Brown wrote:
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13) From: John Brown
two forges
Rich wrote:
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14) From: Rich
I will bet that there is no little sticker that says that they are 
approved.  Don't burn the shop down....
John Brown wrote:
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15) From: John Brown
i normally operate at between 5 and 7 psig. but have gone as high as 10 
psig.
 i have worked repairing Natural gas lines as high as 15 psig dug 
trenches for and helped lay pipe for even higher.  then got back to 
working on the electrical controls for all of the Boilers  for the base 
plumbing shop.
Rich wrote:
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16) From: Joseph Robertson
 John,
I wish our Probat 5kilo was up and running. I would invite you to try
a batch of cocoa in it before you buy. Still a couple of months out
yet.
I wanted to thank you for your help in getting me in touch with Joe
Behm. We are all set up with him.
Best Regards,
JoeR
On Nov 3, 2007 8:45 AM, Alchemist John  wrote:
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17) From: Justin Marquez
If you go back to the chemistry of combustion:
Natural Gas (Methane, a.k.a. CH4):
1 CH4 + 2 O2 + 8 N2  =  1 CO2  + 2 H2O  + 8 N2
Air to fuel = about 10:1 (actually 9.6 :1 since air isn't EXACTLY 20%
oxygen)
Propane (a.k.a. C3H8):
1 C3H8  + 5 O2  + 20 N2  = 3 CO2  + 4 H2O  + 20 N2
Air-to-fuel = about 25:1 (actual = 23.9:1)
Also note that propane is about 2315 BTU/SCF of gas whereas methane (natural
gas) is about 900-1000 BTU/SCF (depending on exactly what stuff has been
left in the "natural gas" by the gas processor who sold it into the
pipeline).
Thus, for the same BTUs, it takes about 43% as much propane, but the air
quantity is still a little but higher (maybe 7-10% more air).  Hence, the
need for different size gas orifices for the propane, which is more dense
and needing a lot les of it than for methane.
(This is probably more than any of you wanted to know, especially those of
you who already knew it.)
Happy Monday!
Safe Journeys and Sweet Music
Justin Marquez (CYPRESS, TX)
On 11/3/07, raymanowen  wrote:
<Snip>
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Safe Journeys and Sweet Music
Justin Marquez (CYPRESS, TX)

18) From: Floyd Lozano
I was thinking the very same thing, except in metric, and also in Dutch.
How close is this to actual, given that the act of combustion changes the
atmosphere local to the combustion site (i.e. you produce CO2 which
potentially changes the concentration of other gasses, though the convection
caused by the temperature gradient would act to flush those products away,
though the heat of the same might also act differently on the different gas
components, meaning some flee the scene quicker than others omg too many
variables brain explosion imminent!
On 11/5/07, Justin Marquez  wrote:
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19) From: Justin Marquez
Floyd,
I am no combustion expert, but I can definitely say that I "painted" the
explanation with a "very broad brush".  The specifics of real combustion
theory is a most complex thing. Most of the time, I expect that it happens
so quickly that true equilibrium is never achieved, which makes a complete
study of it more difficult (like most of life...)
Safe Journeys and Sweet Music
Justin Marquez (CYPRESS, TX)
On 11/5/07, Floyd Lozano  wrote:
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