Blast-Engine

Required in metallurgical operations to force nece ary air into the furnace or converting ve el to effect chemical reactions; usually of the " steeple" type, inverted vertical engines, with fly-wheels below and the air-cylinder above. The steam valves are most frequently of the poppet type, operated usually by cams. The fly-wheels are usually in pairs. Some of the older engines are horizontal, and there are a very few beam engines. The pre ure of the air averages between 8 and 12 lbs. per sq. inch in blast furnace practice, and from 30 to 40 lbs. in steel practice. The air-valves are most often of the flap type, seating upon gratings. See BLOWER.