[TheForge] more gas (the propane kind)

[Mike Linn]

Type-K has a max working temp of about 2282 =B0F (1250=B0C) and loses=20
calibration rapidly after about 300=B0C  at the upper reaches your looking=
 at=20
errors (assuming it still is working properly) of about 10=B0C . And the T/C=
=20
wont lat long at those temps. Its not designed for that.

A better choice is a Type B t/c.  These are designed for an accuracy of +/-=
=20
0.5=B0C above 800=B0C upto 1700=B0C (3092=B0F). Type B is a standard t/c=
 type for=20
industry so it shouldn't be difficult to find an indicator for it.  If=20
worst comes to worst you can measure the emf output with a DMM and look up=
=20
the temp in the ITS-90 charts.

I've seen new  type B indicators for $135 and you should be able to pick=20
them up for surplus.

Mike
Metrologist in my real life.....



At 08:16 PM 04/21/2003 -0700, you wrote:
> > As another mentioned, Omega makes pretty reasonable stuff. A type K
> > thermocouple works well at forge temperatures (to the kind of accuracy
> > we need, anyway) despite being technically beyond it's use range. Get
> > heavy gauge wire for the thermocouple and it will last much longer.
> > Omega will make one up for you for not too much money. One caution, make
> > sure that whatever meter you use will reach the temps you want to
> > measure; the less expensive ones leave off the top end of the scale
> > (might only go up to 1500F or something).
> >
> > Steve Smith
> >

         Michael Linn
       Artist Blacksmith
      McCalla, Alabama
       AFC Webmaster
http://afc.abana-chapter.com=20