Carbolite CF 15 - CF 60 - Manual (Page 12)

12 MF28 3.08
5.5 Thermocouple Replacement
Disconnect the furnace from the supply, and remove the furnace back panel.
Make a note of the thermocouple connections. The negative leg of the thermocouple is marked
blue. Compensating cable colour codings are:
negative positive (type R)
white orange
Disconnect the thermocouple from its terminal block.
Remove the screw or other fitting to release the thermocouple sheath, withdraw the sheath, and
shake out any fragments of thermocouple.
Re-assemble with a new thermocouple observing the colour coding, ensuring that the
thermocouple is not twisted as it is being inserted and that the screw is refitted to grip the sheath.
5.6 Element Fitting and Replacement
Replacements: read the section on element ageing (4.5). If at any time the power limit has been
increased, reset it to its original value (section 8.2), or measure the resistances and recalculate
the limit.
Disconnect the furnace from the electrical supply and remove the side panels to gain access to the
element connections.
Remember that the elements are fragile and expensive, and that they can be damaged by
contamination: handle them with care and keep them clean.
First Fitting: The furnace is supplied with all element connection braids in position, except for 3
off loose braids. Insert the elements as explained below, and connect the fitted braids to the
adjacent element ends. Connect the loose braids in pairs to the unconnected ends, on the same side
of the furnace as the element power terminals.
Replacements: Replace each element in turn. Release the clips using the tool provided. Move the
braids and carefully withdraw each element: it may be necessary to remove the element sleeve
with the element.
Carefully insert the new element, locating the sleeves as shown. Sleeves are fragile: it may be
necessary to use new ones. Ensure that the element hot zone is equally placed within the chamber.
Connect the braids. Check that the braids cannot touch each other or the case, and that there is no
short circuit to earth.
Replace the furnace back panel and connect the furnace to the supply.
If aged elements have been replaced, reset the furnace power limit.
Refit the panels and test the furnace.