Fixed Point Realizing Apparatus

Model 37703 Low Temperature Furnace

Model 37703 Low Temperature Furnace is designed specifically to realize and maintain the freeze plateau of Indium, Tin and Zinc Fixed Point Cells, for calibration of thermometers on ITS-90. The aluminum furnace core, into which the fixed point cell is inserted, is heated by the 3-Zone heaters in noninductive winding controlled individually by the high-resolution controllers (zero-cross control) using platinum thermocouple, and this provides a very low thermal gradient along the core length and low noise at calibration. The variable set point over-temperature trip function can prevent a temperature runaway of the furnace.

*Optionally, a step-down transformer is available for use in AC 200V power.

Model 37702 High Temperature Furnace

Model 37702 High Temperature Furnace is designed specifically to realize and maintain the freeze plateau of Zinc, Aluminum and Silver Fixed Point Cells, for calibration of thermometers on ITS-90. The furnace core is a specially designed heat pipe, which provides a very low thermal gradient along the core length. The heat pipe is heated by radiant heat generated from the heater unit in noninductive winding, which is controlled by the high-resolution controller (zero-cross control) using type R thermocouple. The variable set point over-temperature trip can prevent a temperature runaway of the furnace.

*Optionally, a step-down transformer is available for use in AC 200V power.

The above 2 furnaces were jointly developed with National Institute of Advanced Science and Technology (AIST/NMIJ) to realize the defining points of ITS-90 using the high-purity metal fixed point cells.