Signature Vacuum Systems Inc. of Meadville, Pa., recently shipped a large 6-bar vacuum heat-treating furnace to the U.S. Air Force. The furnace has a 2-foot x 3.5-foot x 9-foot-long graphite hot zone rated for 2450°F. The diffusion pumping system is capable of producing a vacuum in the 10-5 torr range. Also included with the furnace was a cryogenic liquid argon tank, argon accumulator and a powered load truck.