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Heatpipe Furnace Models 17702W, 17702P, 17702S (13
–
07/20)
Principle of operation
The principle of the operation of heat pipes is as follows. The inside walls of the inner and outer tubes are
covered with a fine wire mesh screen. When heated, the small amount of sodium with which the heat pipe
is charged vaporises throughout the interior cavity and condenses on the walls of the cavity. Assuming that
the interior is isobaric, the vapour-liquid transition at the walls is a thermal equilibrium condition which can
only occur at constant temperature. The condensed liquid is returned to the bottom of the structure (for re-
vaporisation) by capillary action at the mesh screen.
In order to prolong the life of the heat-pipe it is necessary to control the rate of temperature increase while
the sodium is in its solid phase. The controller has been programmed automatically to ramp the heat-pipe
temperature at a controlled rate until it approaches 450°C for Sodium, 400°C for Potassium, at which
temperature the medium can be considered molten and the temperature is then allowed to rise at the full
rate.
The controller uses internal alarm features to determine the point which the controlled ramp terminates and
is used to control the ramp rate. These parameters are set at 445(°C) for Sodium and 395(°C) for
Potassium and 7.5(°C/min) and should not be changed.
Changing the Set Point
The main controller will control the Heatpipe furnace. The setpoint is accessible from the Home page of the
controller. The controller circuit will be enabled/disabled by the overtemperature controller on the right of
the main controller.
The Heatpipe furnace set point will adjust the main heatpipe temperature.
To compensate for any errors in the linearity of the display temperature, the user can adjust the linearity
using the 8 point adjustment curve for each furnace. See section below for details on how to do this.
To change the Setpoint of the equipment:
1.
From the ISOTECH homepage, press the SCROLL button once, this will highlight the SETPOINT
ADJUST
box.
2.
Press the SCROLL button once more and this will allow adjustment of the setpoint via the
UP/DOWN
buttons.
3.
Scroll to the desired set point as described above.
4.
When the temperature is set, press the SCROLL button again to enter and save the setting.
5.
The equipment will now raise or lower the furnace temperature as required.
How to globally change from °C to °F or Kelvin:
1.
Log in as the Engineer
2.
Scroll to INSTRUMENT
3.
Scroll to DISPLAY
4.
Scroll to UNITS
5.
Select by pressing the Scroll button
6.
Use up/down to select from °C, °F or Kelvin
7.
Press the Page button to exit and save the selection
