Figure 3 Gas Inlet Tube Assembly - Thermo Scientific BF51841C Operation Manual

Installation
Guidelines for Ashing Applications
Figure 3. Gas Inlet Tube Assembly.
Guidelines for Ashing Applications
Ashing products at relatively low furnace temperatures (400 ° to 800 °C) may
cause carbon residue to build up on the walls, floor, ceiling and heating elements
inside the furnace chamber. The carbon will look like a black powder, similar to
smoke on glass from a candle.
Carbon is an electrical conductor. If the furnace chamber and heating elements
are coated with carbon, an electrical short-circuit may occur and cause the
elements to overheat and burn out.
There is also some danger that the carbon residue will be absorbed through the
surface of the Moldatherm insulation and affect the fully embedded heating
elements.
The best way remove carbon residue from the chamber and elements surfaces is
to operate the empty furnace at a chamber temperature above 900 °C for one
hour. Do this regularly, whenever the chamber interior shows signs of carbon
residue.
Do not scrub or scrape the chamber surfaces, this may damage the heating
elements and the insulation.
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