HM Furnace Gas Seals

The gas seals can be of the same design as those used for the HT furnace. However, the body flow of inert gas is considerably reduced and must be precisely controlled to obtain quiescent conditions, since a higher flow than required will continually remove the surface layer of carbon vapor from the element and cause severe erosion, considerably reducing the life of the element. 

Ar—which is expensive (about eight times the price of N2) and, xmfortunately, with a hairpin type of element, ionizes across the element slot at temperatures about 2000°C. 

He—which is also expensive, does not ionize, but has a high thermal conductivity. Helium can be added to argon to prevent ionization. 

N2— which does not show any evidence of reacting with either the fiber or the furnace element. 

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