You would hook the heating element between the two hot legs to get 240
volts.
You could get another element exactly the same as your existing one and
hook the new element in series with the old element. Or get a new 240
volt element.
I have not used argon for an inert atmosphere, but I don't think you
can put some in and have it stay put. Since it will be hot, it will
expand and probably become lighter than air. I think you will have to
keep putting in some gas to keep any oxygen out. I expect you could
use CO2 just as effectively. I don't know if CO2 breaks down at 1800
to 2000 F but if it does part of it is C. So might work anyway.

If you have a place that is really fireproof, like outside in a car
port, you could use natural gas or propane. You would need to supply
the gas and drive out all the air before getting the temperature going.
You probably ought to light the gas as it escapes from the kiln too.

I have seen commercial melting of alloys ( not steel ) at Westco where
they used natural gas for the heat and to have an inert ( well
non-oxygen anyway ) atmosphere. The gas burned supplied to the inside
of the ovens burned as it escaped.

Dan


rashid111 wrote:
Folx,

I've been using home made kiln (omega PID + SSR + nichrome wire +
some refractory bricks) to heat treat A2 and similar for some time
now and it all works great.

I am thinking about moving up - expanding the internal volume somewhat
and that will require going 240V (I want to be able to reach reqd temps
in minutes and with my 9x4x4 cavity 110V @ 15A barely makes it).

I will keep most of electronics - only replace the spiral to longer
one. About wiring - do I get it hooked up between 2 hot legs of 240
( in series with SSR of course) ? I will use the ground to ground the
oven . Otherwise I'd need to use 2 spirals in parallel (hots to
neutral) and doing that will
require 2 SSRs (what pros/cons of these 2 methods ?). Was thinking
about getting an electrician to give me a dedicated 240V in garage,
with 20A breaker .

And about argon: for now I use tool wrap steel and it works OK, but
I do get some scaling and softer decarb in the outer layer - which I
grind off. Even using the paper-in-the-foil-bag trick. Assuming I have
a top-load oven and it's rather air tight below the lid, can I simply
flood the interior with 2-3 CF of argon before starting the heat treat
cycle ? Being heavier than air , will it stay "put" inside of the oven
- even when heated up to 1800F-2000F ?

I know some people keep moving inert gas through the oven throughout
the cycle (at slower rate), might need to do the same. Drill a smallish
hole through firebrick, stick some time of copper tubing with connector
to attach the argon hose to - am I correct in my thinking ?


What are typical prices for smaller argon bottles (need pure argon I
reckon, not the CO2 or Oxy mixes) ? Will also need a flow meter .
Also am I correct in assuming that argon is 100% to use ?



Any advice's most appreciated