Stovers,
I think that Hugh is not on the Stoves Listserv and cannot post
messages. So I am forwarding his reply to all of you.
In response to Boston's comment, he is correct about the parts of the
stoves that are NOT in the direct pyrolysis and combustion pathways.
The galvanizing will remain intact if surfaces are under 200 C.
Thanks to all for the responses.
Paul
Paul S. Anderson, PhD aka "Dr TLUD"
Email: [email protected] Skype: paultlud Phone: +1-309-452-7072
Website: www.drtlud.com
On 2/1/2013 2:08 PM, Hugh McLaughlin wrote:
My perspective on this is it takes real stupidity to be harmed by
galvanized stove parts.
The core concern is arc welding galvanized material - which vaporizes
the zinc metal rapidly enough that it does not oxidize to zinc oxide.
Then you have to breath in the zinc-laded smoke - again rather easy to
avoid. The same effect happen in spot welding, but in smaller quantities.
If you are exposed, you get a flu-like response. See
http://en.wikipedia.org/wiki/Metal_fume_fever
The real issue is processes that deal with molten zinc, such as when
casting zinc. But even then, the risks of burns outweighs the zinc
inhalation concern.
For stoves, a slow heating of the galvanized surface in the presence
of air will oxidize the surface and render it less scary. However, it
should be noted, that if you lick the zinc oxide off the ductwork, you
will get the same metabolic effect.
I recommend the same precaution for galvanized materials as I do for
any painted materials or recycled tin cans - burn the completed unit
first time outside in a well ventilated area - and avoid sucking up
excess smoke. Your lungs will tell you when something is disagreeable,
and react accordingly.
Hugh McLaughlin, PE
------------------------------------------------------------------------
*From:* Paul Anderson <[email protected]>
*To:* Discussion of biomass cooking stoves
<[email protected]>
*Sent:* Friday, February 1, 2013 2:38 PM
*Subject:* At what temperature are the bad gases from zinc created, vs
harmless zinc oxide?
Stovers,
Galvanized metal in stoves gets mentioned occasionally. Do we have a
clear answer about what is the temperature at which the zinc makes
poisonous gases (such as when welding) versus making zinc oxide (the
white stuff that you can by in a tube to put on your nose to prevent
sunburn)? Is it bad if the temperature is at 400 C to 700 C? Or does
it need to get much higher?
Paul
-- Paul S. Anderson, PhD aka "Dr TLUD"
Email: [email protected] <mailto:[email protected]> Skype: paultlud
Phone: +1-309-452-7072
Website: www.drtlud.com <http://www.drtlud.com/>
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