HomeRoast Digest

Topic: Air pressure / volume for bean roaster (5 msgs / 100 lines)
1) From: Robert Wolfe
Heat gun questions for do-it-your-selfers;
How much air pressure does it take to agitate the beans?  Can you make 
sense of this in cfm, or does it need to be figured in psi?   I've found 
some 1800 watt heat guns that produce .333 psi, with infinitely variable 
temperture settings. Is that sufficient for a half pound of green 
coffee?  What kind of airflow does a HWP generate?
Thanks in advance to any who provide answers!
Robert Wolfe
Oregon Pinot Noir Club
816 Nantucket Ave.
Eugene, OR 97404
Locals Only line: 607-1745
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2) From: Robert Cantor
I've tried heat guns under $100 and haven't found any that would move 1/2
pound of beans.  There are $400 models that might, though.  There are rumors
of heatgun based roasters, so keep looking.  I've never measured airflow.
Bob C.

3) From: Ed Needham
it's more than just air volume.  It's static air pressure and volume.
If the air flow has lots of volume but can easily be impeded, the beans
won't agitate.  On the other hand, if there is static pressure but not
much volume, there won't be enough air to agitate the beans.
I don't know what the figures are, but I'm betting on a Fasco 365 CFM
squirrel cage blower to power my latest garage roaster project.
Ed Needham

4) From:
A squirrel cage blower is what powers the Coffee Kinetics roaster.  I had a
problem a few weeks ago with very uneven roasting.  Some of the beans were
at second crack before first crack ever hit the majority of them. The
problem had crept up so slowly I never realized what was going on!  I had
seen some uneven roasts in Sulawesi over the last month, but I actually
thought maybe the beans were getting old, until it got so pronounced that it
became apparent something was wrong.  I dismantled the machine and found the
fan and all other parts covered in a thick layer of dust.  After a complete
cleaning the airflow is back to normal and I have put a furnace filter over
the intake.
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5) From: Ed Needham
Yeah...a filter of some sort is probably necessary.  I plan on using the
intake for the blower as a device to pull air through the roasted beans
to cool them.
Ed Needham

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