Construction; Pt/Pt.rh Type 'S' Thermocouple - Bartington MS2 Operation Manual

Note: The meter is pre-set for normal operations and the front panel manual controls
should not be used if the equipment is operated with a computer running GeoLab. For
stand-alone applications without a computer, the front panel controls should be used to
select the thermocouple type to be the same as set by the manual switch on the side of the
furnace unit. Bartington Instruments is unable to advise on this latter mode of operation.
The MS2WF furnace and MS2WFP power supply are connected via an 8-way cable for the
transmission of data and power.

17.2. Construction

The 17mm internal diameter silica tube is non-inductively wound over a 45mm length with a
platinum wire heating element which, when supplied with current, will uniformly heat a sample
placed at its centre. Stray magnetic fields within the furnace are extremely small. A 4mm layer
of silica fibre insulating material reduces the surface temperature to approximately 100
making the furnace suitable for use within the sensor cavity. The refractory materials used in
this furnace are free from magnetic contaminants and contain no asbestos.
Note: The recommended sample size to obtain uniform heating is 15mm diameter x 15mm
length.

17.3. Pt/Pt.Rh type 'S' thermocouple

This is housed in a 4mm x 160mm mullite sheath which can be clamped, using a 3mm diameter
locking screw, at any height within the furnace.
The sample is placed in close contact with the tip of the Pt/Pt.Rh type 'S' thermocouple. In this
way, very accurate temperature measurements of the sample are accomplished.
Note: To minimise the generation of sample thermal gradients, the sample should not
come into contact with the furnace wall. The sample should therefore be drilled and
mounted on the tip of the type 'S' thermocouple pillar. A hole depth of one third of the
sample length is suggested for good thermometry.
Ceramic crucibles with an internal diameter of 13mm and a depression in the base to fit on the
thermocouple are supplied with the system for the measurement of granular samples.
Silica fibre insulating plugs are fitted at the ends of the heated section. These are essential for
the achievement of high sample temperatures with low thermal gradients, and can be re-made
and replaced by the user to maintain good magnetic hygiene.
The furnace is guaranteed to perform to its full specifications for 1000 hours cyclical use. The
heating element is cemented into place using caked alumina to tolerate the stresses induced by
frequent heating and cooling cycles.
BARTINGTON INSTRUMENTS
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