On 3/19/2011 10:36 AM, Winston wrote:
Joseph Gwinn wrote:
In ,
Laurie wrote:

Looks interesting but the web site is a little short on details.

http://www.multiplaz.com/

Typical information-free site for sure. Pretty, though.

The key is to use steam as the working fluid in what is essentially a
TIG torch. They claim steam or steam+alcohol to be almost as good as
argon, and a lot cheaper.

I was able to find the US patents, having gleaned the names of the
inventors from their awards:

6,156,994; 6,087,616; 5,719,370; and 5,609,777.

How very intriguing! Chem E's, a little help please?

I'm a Chem Eng (retired) but not sure I can comment with any great
authority. However:


Would it be more proper to say that the water+alcohol mixture
changes state from liquid to steam to hydrogen + oxygen gas
to plasma in the torch head, (rather than from liquid to steam)?

I suspect that is what's happening. The plasma disassociates the water
into H2 & O2 which then recombine to deposit heat energy at the work
piece. This would be something similar to an "atomic" oxy-hydrogen
torch in which H2 gas is disassociated by a plasma into elemental
(atomic) H which then recombines in a similar fashion producing a higher
temperature than oxygen/hydrogen alone.




I suspect the alcohol just lowers the vapor pressure of the
mixture, yes?

Alcohol would reduce the vapour pressure but it's hard to say what role
it would actually play. Maybe it simply provides a source CO2 to act as
a shield or maybe it acts as a reducing agent to take up any stray O2
around the weld

Laurie Forbes



..Though I admit the inventor curiously claims "Plasma Steam"
in 5,719,370 and 5,609,777.


--Winston