HomeRoast Digest


Topic: Chaff Fire in my Freshroast (5 msgs / 143 lines)
1) From: Sam Tregar
So I set up the first batch of Ethiopia Organic Sidamo Moredocafe last
night.  I used the same amount of coffee as usual for my Freshroast,
2 rounded scoops.  About halfway through the first crack I noticed a
red glow coming from the chaff collector and I smelled melting
plastic!  I quickly turned off the machine and dumped the coffee into
my sink - when I did I could see that the chaff had gotten bunched up
in the top of the collector, probably the cause of the fire.
Any ideas about why this happened?  It's been rather humid here in New
York lately - could that have contributed?  Or perhaps this coffee is
more chaffy than most?
I'm going to try roasting a different coffee this morning, keeping a
close eye on it.  I'm hoping the brief fire didn't damage the
machine...
-sam

2) From: Homeroaster
Ooooooh!  That's a bit scary and unfortunate.  If one tiny glowing piece of 
chaff gets up with the others, it can cause a fire.  I have a friend who is 
a commercial roaster in the St. Louis area that vacuumed a bunch of chaff 
from his roaster and got a hot chaff ember inside the vacuum.  He ended up 
dragging the burning shop vac through a busy mall to extinguish the flames 
outside the mall.  Smelly, but luckily it didn't smolder until he closed the 
shop and went home for the evening.
*********************
Ed Needham
"to absurdity and beyond!"http://www.homeroaster.com*********************

3) From: Eddie Dove
Sam,
Dry Process (DP) coffee = LOTS OF CHAFF
Some roasting appliances (like my Gene Cafe) actually have a different
"Fill Line" for Dry Process coffees, which is lower than the normal
"Fill Line."
I hope your Freshroast is okay ...
Respectfully,
Eddie
-- 
Vita non est vivere sed valere vita est
Roasting Blog and Profiles for the Gene Cafehttp://southcoastcoffeeroaster.blogspot.com/On 7/28/07, Sam Tregar  wrote:
<Snip>

4) From: Aaron
Im going to have to say that any roaster that collects the chaff 
somehow  is susceptable to chaff problems.  (versus say a roaster that 
blows it all over the yard.. as an example)  If you get it hot enough,  
now force air through it,  or worse yet, introduce an ember to it, it 
will go up in flames.
I do not know for sure the ignition temp of chaff, but looking at it, 
will say its probably close to paper, which is the a rough equivalent 
from another type of plant... and that's around 451 where that 
ignites....  and what temps do we roast our coffee's around?
Hopefully you didnt ruin your roaster and caught it at the right time, 
but this is a lesson for everyone who roasts,  never EVER leave your 
roaster unattended, things can and do happen, and they can turn out very 
tragic if you are not attentive.   Not that you didn't do this, but as 
another lesson for us roasters, keep your equipment clean, VERY clean,  
make sure as in the case of an I roast, or gen cafe, or even a hot top, 
you get all the chaff and chaff pieces / partses / and dusties out of 
the nooks and notches that it likes to collect in lest they  start 
adding up and turn into a pile of kindling.
++++++
On the chaff issue,  I can't answer for this particular coffee but yes 
some are way more chaff producing than others.  I have done some 
coffee's where when I was finally done...the chaff collector was full, 
and it was well.... backed up throughout the coffee in the roast 
chamber....  I have had others where it was very minimal, and I had to 
read the label again to make sure I didnt grab a decaf by mistake.   A 
big pile of chaff can reduce airflow, increase temps in the heater and 
potentially add to a fire problem.   Unless you left chaff in there from 
a previous batch,  for an extended period of time, I don't see where the 
humidity really would have caused the chaff accumulation as the water 
would have driven off way before the beans reached the temp where they 
start letting loose the chaff in earnest.
Good luck and let us know if your unit still works correctly.   Might 
want to check the seals and all in the assembly that the fire did start 
in, check for any deformations / cracking / burnt gaskets etc ...
Aaron

5) From: Sam Tregar
On Sat, 28 Jul 2007, Aaron wrote:
<Snip>
All good advice.  I do clean my roaster regularly, but perhaps I
need to do a better job!
<Snip>
This morning I noticed two sizable cracks in the base of the roaster.
I'm pretty sure they're new, although I'm at a loss as to how they're
related to the fire.  Maybe the backed-up chaff caused the base to
overheat too?  In any case, I think I'll have to chuck the base...
Luckily I happen to have an extra Freshroast base, so I'm still in
business.  The chaff collector and roasting chamber both appear
unharmed and the batch of Brazil Moreninha Formosa I roasted this
morning tasted great.
-sam


HomeRoast Digest