M970-07/04
PAGE 7
This separate centre work tube is normally 2.55ins. internal diameter (65mm) and can
be used with metal equalizing blocks up to 2.3 ins. Diameter (58mm) for mounting
probes to calibrate. This smaller diameter / area work tube maintains a lower
horizontal uniformity over the temperature range using a metal equalizing block of 200
to 250mm.length.
This separate work tube is easily replaced compared to the main outer work tube
which is wound with the heater windings. This also enables a range of smaller work
tube diameters to be easily fitted by simply changing the 2 insulated outer end plates
and metal covers. These insulated and separately spaced outer end plates from the
main furnace provide an additional “heat barrier” at the hot furnace ends when
temperatures above 600 deg.C. are used.
