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Grieve’s No. 855 is a 1,250°F electrically heated, inert-atmosphere, heat-treating cabinet oven. The oven measures 38" × 26" × 38" and is heated by 40 kW installed in Incoloy-sheathed tubular elements, while a 1,500-cfm, 1 ½-hp recirculating blower provides horizontal airflow to the workload.

This oven features 10" insulated walls; a Type 304 2B-finish, stainless-steel interior with continuously backwelded seams; and inner and outer door gaskets. The inner gasket seals directly against the door plug while the outer gasket seals directly against the face of the oven.

The inert-atmosphere construction also includes a pressure regulator, flow meter, pressure gauge, internal high-temperature gasket, all-welded expansion connection in doorway throat, air jacket on inner oven for cooling, ½"-thick silicone rubber atmosphere seal, blower shaft seal, positive latching door hardware, adjustable offset door hinges, outlet with pressure relief, and wall penetrations fitted with compression fittings. A 325-cfm blower pulls air through the air jacket on the inner oven for cooling.

Controls on the oven include a special heating/cooling temperature controller and a modulating damper on the cooling blower. The oven also has an SCR power controller and circular chart recorder.