Abstract: A door seal especially adapted to for use in a high temperature furnace wherein a sealing gas is controllably introduced between confronting surfaces of the door and the furnace to establish a gas barrier against leakage of cover gas from within the furnace chamber and leakage of air into the furnace chamber.

Abstract: A heat processing system in which a product is efficiently conveyed through a high temperature furnace and in which the product can be stored within a section of the furnace at a temperature less than the critical temperature to which product exposure must be limited. The furnace includes multiple sections each of a respective operating temperature, one of the sections being of high temperature to which a product can be exposed for only a limited time. A supply of product carriers is contained within the furnace onto which a product is supplied for transport forwardly through the furnace for unloading at an opposite end thereof, the carriers being returned rearwardly through the furnace back to a loading area. During an emergency mode of operation, loading of the product is discontinued and the product already within the furnace is transferred from the critical heat section to an adjacent section for storage at a lower temperature less than the high critical temperature.

Abstract: A muffle seal for a high temperature furnace in which a quartz or similar muffle is attached to an associated metal structure to provide substantial sealing of gas in the muffle even at extremely high operating temperatures. As employed in a multi-zone furnace having a high temperature quartz muffle section and a lower temperature metal muffle section joined thereto via a gas or gas and heat barrier, the quartz muffle is joined to the barrier by a peripheral chamber provided around the end of the quartz muffle confronting the barrier, the chamber being sealed to surfaces of the muffle and the barrier by porous gaskets. A sealing gas is introduced at above atmospheric pressure to the peripheral chamber, the gas being controllably transmitted through the porous gaskets to provide isolation against leakage of gas within the quartz muffle. The novel seal can also be employed to join quartz and metal muffle sections without a barrier therebetween.

Abstract: A high temperature unitary electrical resistance heater which is mechanically supported throughout its active length but spaced from a refractory base with the heating element being substantially free of the supporting structure to provide an efficient heater having relatively low thermal inertia while being rigidly supported for high temperature operation. A flat continuous electrical resistor ribbon is disposed in a multiple loop configuration having a plurality of spaced heater segments with flat confronting surfaces and a plurality of legs outwardly extending from an edge of the ribbon and secured within a refractory base to support the ribbon in spaced relation to the refractory base.

Abstract: A high temperature unitary electrical resistance heater which is mechanically supported throughout its active length but spaced from a refractory base with the heating element being substantially free of the supporting structure to provide an efficient heater having relatively low thermal inertia while being rigidly supported for high temperature operation. A flat continuous electrical resistor ribbon is folded in a multiple loop helix-like configuration formed of a plurality of straight segments and a repetitive array of folded, overlapped corner portions. A strut is interposed within each folded corner and welded therein, outwardly extending end portions of each strut being rigidly secured in a refractory base structure with the resistor ribbon being spaced along its active length from the base structure.