Alan and anyone interested

>we are thinking of doing this
>with a furnace rather than a torch and wonder if anyone else is doing so
>and what kind of furnaces they can recommend. It appears to us that a
>furnace capable of 1200 C is adequate.

We are using an infra-red red furnace for water and hydrogen extractions of
minerals.  The temperature of the infra-red furnace is accurately
controlled by a "thermal programme controller" (both made in Japan by
Ulvac, see details below) which enables one to heat a sample in several
different ways. The temperature is monitored by a Pt-Rh thermocouple which
rests on the sample (in molybdenum foil). The max temperature one can
safely work at is 1400 C.  The furnace wasn't designed specifically for
stable isotope work (testing of thermal properties of ceramics and metals)
so initially we battled to get good vacuum. This problem has been overcome
after minor improvisation.  In the work I have been doing I need to do
extractions at different temperatures (accurately) and it would be
impossible to do this without the infra-red furnace and temperature
controller.

The main down side of this set-up is cost and speed (only one sample at a
time). The whole tooty will probably cost in the order of US$ 14 000 (using
US$ 1 = Yen 100). The thermocouple gets a little fragile after ~200
extracts and if this breaks it will cost about US$ 400 to replace. In total
a Vennemann and O'Neil type extraction line probably costs less than one
thermocouple!  I hesitate to recommend the Ulvac furnace because of it's
high cost and a few design problems (mainly because it wasnt intended for
stable isotope work) but if money is not an issue and your work requires
more than a "flame thrower" then yes, get one.

Kevin

Infra-red furnace( E45P), transformer & stand ($7000)
Temperature controller (TPC-1000) & power unit ($3000)
Quartz glass chamber & boat for sample ($4000)

Ulvac Sinku-Riko
Yokohama-shi, Midori-ku
Shiroyama-cho 300
226
Japan
Fax: +81-45-934-0448


**********************************************************
Department of Geochemistry
Geological Survey of Japan
1-1-3 Higashi
Tsukuba
Ibaraki 305
Japan