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Heatpipe Furnace Models 17702W, 17702P, 17702S (13
–
07/20)
CALIBRATION APPARATUS FOR ZINC, ALUMINIUM AND SILVER
FIXED POINTS
GENERAL ASSEMBLY OF FIXED POINT CELL INSIDE THE HEATPIPE
A
Insulation: Superwool 670HT 932-20-52 (to keep
thermometer head cool)
B
Fixed Point Cell
C
Inconel Cell Basket
D
Ceramic Spacer 420-02-08 (at bottom of heat
pipe)
INTRODUCTION
Using high temperature thermometers presents many problems due to strain and contamination, which can
very easily be introduced into the thermometer during thermal cycling.
Limited understanding of the relevant mechanisms has resulted in a dearth of published information and of
available apparatus for the safe treatment of these sophisticated devices.
DESCRIPTION
Sufficient information now exists at Isotech to allow introduction of a new apparatus, specifically designed
not only to realise and maintain the ITS 90 fixed points of zinc, aluminium and silver, but also to pre- and
post-condition the thermometers to be calibrated. To this end a second furnace has been incorporated,
which, because of its design, will permit conditioning to be carried out safely and without introducing
contaminants into thermometers.
Complementary features of the apparatus are a pre-calibration tube (held at the temperature of the fixed
point) made of a unique and gas tight material, together with a rack for storage of up to 4 thermometers at
approximately ambient temperature.
