Explosion-proof electric air heater

An electric heater, particularly adapted to heat air in hazardous areas, comprising:

• a tubular, sheet-metal casing,
• a motor-driven fan for moving air axially through said casing,
• a plurality of heat-radiating members disposed within said casing, each in position crosswise of the latter, each of said members being in the form of a metal casting and having an electric heat-generating element embedded therein,
• each of said radiating members having an annular central hub and a plurality of integral fins extending radially thereof, said fins on each radiating member being wider than the central hub to overhang the latter in a direction axially of said casing,
• said radiating members being serially arranged axially of said casing, and abutment means in the form of flat-faced bosses on certain of said fins for interabutment to predetermine the serial spacing of said radiating members,
• a pair of legs integral with and extending radially of each of said central hubs and having integral foot means at the ends thereof, the terminal ends of said heat generating element being embedded within respective legs and having terminal extremities extending outwardly from said legs and said foot means,
• a metal terminal box having an opening in a wall thereof, said terminal extremities of each of said heat generating elements extending through said opening and into said box, and
• said foot means of each of said radiating members being welded to said terminal box wall to seal the opening therein.

An electric heater, particularly adapted to heat in hazardous areas, comprising:

• a tubular, sheet-metal casing:
• a motor-driven fan for moving air axially through said casing,
• a heat radiating member disposed within said casing in position crosswise of the latter, said member being in the form of a metal casting and having an electric heat-generating element embedded therein,
• said radiating member having a ring-like hub positioned in axial relation with respect to said casing and plurality of fins extending radially outwardly from said hub,
• said hub having an annular outer surface inclining from a smaller diameter to a larger diameter in the direction of air flow through said casing to provide a Venturi effect on air blown through said casing by said fan and to thereby draw air from the center of said hub to the outer periphery thereof.