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Note: The type ‘T’ thermocouple is for low temperature measurements and is not
recommended for use in conjunction with the furnace.
To maintain good magnetic hygiene and efficient heating, the plugs at the top and bottom of the
furnace should be replaced when they appear to become fragile or dirty. Contamination of the
furnace can be evaluated by occasionally performing a temperature measurement sequence
with no sample in place. In the absence of contamination, no magnetic transition behaviour will
be observed.
The efficient performance of the furnace depends, to a very great extent, on the quality of the
insulation material provided. The insulating material is a low cost, silicate fibre fabric which can
be wound into a regular shape.
WARNING: When the furnace is first heated, or first heated after renewing the insulation,
the binder material in the insulation is burnt off and produces unpleasant fumes. Some
samples may also produce fumes during heating. Ensure good ventilation is provided at all
times and avoid breathing the fumes.
Thermal plugs are fitted at the top and bottom of the heated section of the furnace. The
thermocouple probe passes through the lower plug.
Plugs should be prepared in the following manner.
1. Cut a 400mm x 30mm strip of the insulating material provided using a ruler and scalpel, and
wind into a cylindrical shape. The lower plug should be wound round a 4mm former (e.g.
4mm drill) to provide entry for the thermocouple. The end of the winding should be secured
in place with Fortafix Light Grade High Temperature Cement to prevent the plug from
unwinding.
2. Push the lower plug down into the furnace until it is flush with the base of the furnace silica
tube.
The upper plug need only be pushed in half way whilst performing high temperature
measurements and will require frequent replacement.
This should seldom need to be replaced. If it does, proceed as follows:
1. Remove the old insulation.
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