Carbolite VST 17/-- - Manual (Page 10)

1700° Tube
10 LMF32C – 1.07
4.7 Element Installation & Replacement
Safety Warning – Molybdenum Disilicide elements.
The elements form a glazed surface when heated. Internal stresses can form
through heating and cooling which render the glaze fragile. The glaze can
sometimes splinter into a shower of sharp particles when handled. Always wear eye
protection when handling the elements.
Handle the heating elements with extreme care as they are very fragile. Also, avoid touching the
heating surface (the thin part of the element).
Replacement: Note the length of element above the fixing clamps before starting. Remove the
aluminium braids and clips. Remove the clamp, which has a screw fixing. Lift out the old element
and insulation piece (element block): handle the insulation piece with care as it is fragile.
The element diagram shows the items which must be assembled and fitted. Examine and identify
the loose components. There are variations in the positions of the braids which connect the
elements: the rule is that for single phase all elements are in series; for 3-phase or 3-zone, each
phase or zone has elements in series.
Fit the insulation piece (element block) to the element. Locate the clamps over the element, and
tighten carefully. Lower the element into position, and connect the braids using the clip tool
provided or hand pressure, depending on the type of clip.
Ensure that the element is correctly placed: the thin part of the element legs should be entirely
within the heating chamber; the element should not touch the bottom of the chamber, nor the work
tube.
Replacement: heat up the furnace to a moderate temperature and ensure that the furnace is
controlling properly, in case the previous element failure resulted from a fault in the control
system.
After installing new elements run the furnace at 1500°C for an hour. This creates a protective
glaze on the element surface.
larger clips require clip tool, comprising two levers
smaller clips do no require clip tool