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Saturn model 877 Iss.08– 08/14
THEORY OF OPERATION
The major problem of calibration furnace systems has been what is called "end effects".
This is the problem encountered in any tubular furnace due to the fact that the ends of the tube tend to be cooler
than the central part of the tube.
To compensate for this, windings that heat the tube are specially profiled to give a uniform area of constant
temperature in the central part of the tubular oven or furnace.
To further even out the temperature gradients, metal or ceramic equalising blocks are introduced.
With enough effort this fundamentally unsound device can be made to give fairly good results.
The theory behind the Isotech Saturn Furnace is that a solid conducting sphere suspended in the centre of a hollow
outer, heated sphere will take up the temperature of the outer hollow heated sphere by convection and radiation to
give a very stable temperature reference without end or edge effects.
The second step in the design of the sphere was the assumption that the point at the centre of the inner solid sphere
would be not only at a stable temperature, but would be virtually unaffected by short term fluctuations in the
temperature of the outer hollow heated sphere.
In practice, the above assumptions have proved correct and after considerable development have enabled a practical
realisation of the theory to become available.
A number, up to 16, of close ended pockets have been introduced into the central sphere along a circumference.
These pockets meet the very centre of the inner sphere, thus tapping the source of uniform unfluctuating
temperature.
The larger the number of pockets and the larger each pocket becomes the further from the centre of the inner
sphere are the ends of the pockets.
To compensate for this the central sphere is made larger so that there is a slower response to temperature changes
and a longer time to stabilise.
Unlike its competitors, the Saturn Furnace rewards the patience of its user. The longer the furnace is left, the more
any temperature gradients inside the inner sphere even out.