Devices under subclasses 406.1+ comprising boilers having conduits located inside the boiler and generally below the water line for accelerating the circulation of the water in the boiler. These conduits may consist of tubes, inverted bells, cylinders, or even plates spaced apart from each other or spaced from the boiler walls or tubes.
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36, and 407, for special types of circulating devices.
59, for conduits, either internal or external, for aiding the circulation of horizontal fire tube boilers with a drop water firebox.
83, for plates or diaphragms, arranged transversely of a horizontal fire tube boiler for aiding the circulation.
118, for internal circulation tubes, cylinders, or sleeves for vertical fire tube boilers.
159, for internal circulation tubes, cylinders, or sleeves for vertical flue boilers.
379+, for internal circulating conduits combined with water purifying and boiler cleaning apparatus. 412+, for circulation features combined with feed water heaters.
488, for circulation devices combined with a steam separator.
