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<P>Hey Paul, </P>
<P>Like Hugh said don’t worry about it. If zinc fumes were as toxic as most
people think I would have been dead 20 years ago. I have literally welded miles
of galvanized duct. I avoid the fumes of course.</P>
<P>It is not good to breath any welding fumes. The best way to vent a welders
space is to set up a small fan from one side to the other, not front to back or
back to front. The fan should move enough air out of the space without
interfering with the welding gas. The flow should be from side to side not from
behind you. From behind will create eddies and you will be eating
fumes, a little welders jargon. After you have moved the fumes out of the
welders space, use an exhaust hood or general room exhaust to purge the fumes
out of the room.</P>
<P>You have to be more careful with low ceilings. If you can smell zinc fumes
stop until you get the ventilation right. </P>
<P>I know of 3 kinds of galvanized metal, one is hot dipped another is
electroplated and the newest and best one is called “Galvaneal” where the zinc
is melted into an bonded with the steel.</P>
<P>Galvaneal will take more heat than galvanized metal and retain the zinc
coating. Another benefit to this amazing metal is that it is paintable. The
galvaneal that I am using is stiffer than normal galvanize and does not dent as
easily, and it is easier to weld. To weld galvanized use trimix gas. You can't
beat galvaneal for a stove body and other parts that are not in direct contact
with fire.</P>
<P>I have used it in direct contact with fire without burning off the zinc as
long as there is an air circulation around the burner. If you use insulation in
direct contact with a metal burner it will fail much more quickly.</P>
<P>Lanny</P></SPAN></FONT></DIV>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=psanders@ilstu.edu href="mailto:psanders@ilstu.edu">Paul Anderson</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=wastemin1@verizon.net
href="mailto:wastemin1@verizon.net">Hugh McLaughlin</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Cc:</B> <A
title=stoves@lists.bioenergylists.org
href="mailto:stoves@lists.bioenergylists.org">Discussion of biomass cooking
stoves</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, February 01, 2013 3:26
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [Stoves] At what temperature
are the bad gases from zinc created, vs harmless zinc oxide?</DIV>
<DIV><BR></DIV>
<DIV class=moz-cite-prefix>Stovers,<BR><BR>I think that Hugh is not on the
Stoves Listserv and cannot post messages. So I am forwarding his
reply to all of you.<BR><BR>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.<BR><BR>Thanks to all for the responses.<BR><BR>Paul<BR><PRE class=moz-signature cols="72">Paul S. Anderson, PhD aka "Dr TLUD"
Email: <A class=moz-txt-link-abbreviated href="mailto:psanders@ilstu.edu">psanders@ilstu.edu</A> Skype: paultlud Phone: +1-309-452-7072
Website: <A class=moz-txt-link-abbreviated href="http://www.drtlud.com">www.drtlud.com</A></PRE>On
2/1/2013 2:08 PM, Hugh McLaughlin wrote:<BR></DIV>
<BLOCKQUOTE cite=mid:1359749280.99710.YahooMailNeo@web84511.mail.ne1.yahoo.com
type="cite">
<DIV style="BACKGROUND-COLOR: #fff; FONT-FAMILY: arial,
helvetica, sans-serif; COLOR: #000; FONT-SIZE: 12pt">My perspective
on this is it takes real stupidity to be harmed by galvanized stove
parts.<BR><BR>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.<BR><BR>If you are exposed, you get a flu-like response. See <A
class=moz-txt-link-freetext
href="http://en.wikipedia.org/wiki/Metal_fume_fever">http://en.wikipedia.org/wiki/Metal_fume_fever</A><BR><BR>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.<BR><BR>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.<BR><BR>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.<BR>
<DIV><SPAN><BR></SPAN></DIV>
<DIV>Hugh McLaughlin, PE<BR></DIV>
<DIV style="FONT-FAMILY: arial, helvetica, sans-serif; FONT-SIZE: 12pt">
<DIV style="FONT-FAMILY: times new roman, new york, times,
serif; FONT-SIZE: 12pt">
<DIV dir=ltr><FONT size=2 face=Arial>
<HR SIZE=1>
<B><SPAN style="FONT-WEIGHT: bold">From:</SPAN></B> Paul Anderson <A
class=moz-txt-link-rfc2396E
href="mailto:psanders@ilstu.edu"><psanders@ilstu.edu></A><BR><B><SPAN
style="FONT-WEIGHT: bold">To:</SPAN></B> Discussion of biomass cooking
stoves <A class=moz-txt-link-rfc2396E
href="mailto:stoves@lists.bioenergylists.org"><stoves@lists.bioenergylists.org></A>
<BR><B><SPAN style="FONT-WEIGHT: bold">Sent:</SPAN></B> Friday, February 1,
2013 2:38 PM<BR><B><SPAN style="FONT-WEIGHT: bold">Subject:</SPAN></B> At
what temperature are the bad gases from zinc created, vs harmless zinc
oxide?<BR></FONT></DIV><BR>Stovers,<BR><BR>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?<BR><BR>Paul<BR><BR>-- Paul S. Anderson, PhD aka "Dr
TLUD"<BR>Email: <A href="mailto:psanders@ilstu.edu"
ymailto="mailto:psanders@ilstu.edu"
moz-do-not-send="true">psanders@ilstu.edu</A> Skype: paultlud
Phone: +1-309-452-7072<BR>Website: <A href="http://www.drtlud.com/"
target=_blank
moz-do-not-send="true">www.drtlud.com</A><BR><BR><BR><BR></DIV></DIV></DIV></BLOCKQUOTE><BR>
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