page_title: Vertical fire-tube boiler
section_title: Submerged tubes
hierarchical_section_title: Vertical fire-tube boiler / Drawbacks / Submerged tubes
caption_attribution_description: English: Identifier: farmengineshowto00step (find matches) Title: Farm engines and how to run them; the young engineer's guide ... with special attention to traction and gasoline farm engines, and a chapter on the science of successful threshing Year: 1910 (1910s) Authors: Stephenson, James H Subjects: Farm engines Traction-engines Publisher: Chicago, F.J. Drake &amp; Co. Contributing Library: The Library of Congress Digitizing Sponsor: The Library of Congress View Book Page: Book Viewer About This Book: Catalog Entry View All Images: All Images From Book Click here to view book online to see this illustration in context in a browseable online version of this book. Text Appearing Before Image: FIG. 5. SECTION VIEW OF HUBER RE-TURN FLUB BOILER. 16 YOUN.G ENGrNEERS GUIDE. through the tubes, while in the latter the water is in thetubes and the fire passes around them. In this type of boiler there is an upper cylinder (of Text Appearing After Image: FIG. 6. FREEMAN VERTICAL BOILER. more than one) filled with water; a series of small tubesrunning at an angle from the front or fire door end of theupper cylinder to a point below and back of the grates, BOILERS. 17 where they meet in another cyHnder or pipe, which isconnected with the other end of the upper cylinder. Theportions of the tubes directly over the fire will be hot-test, and the water here will become heated and rise tothe front end of the upper cylinder, while to fill the spaceleft, colder water is drawn in from the back pipe, fromthe rear end of the upper cylinder, down to the lower endsof the water tubes, to pass along up through them to thefront end again. This type of boiler gives great heating surface, andsince the tubes are small they will have ample strengthwith much thinner walls. Great freedom of circulationis important in this type of boiler, there being no con-tracted cells in the passage. This is not adapted for aportable engine. UPRIGHT OR VERTICAL TYPE OF BO Note About Images Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.
context_page_description: A vertical fire-tube boiler or vertical multitubular boiler is a vertical boiler where the heating surface is composed of multiple small fire-tubes, arranged vertically.
  These boilers were not common, owing to drawbacks with excessive wear in service. The more common form of vertical boiler, which was very similar in external appearance, instead used a single flue and water-filled cross-tubes. Another form used horizontal fire-tubes, even where this added complexity, such as the Cochran boiler.
  Where a sustained high evaporative capacity was required, vertical tubes were used, but rarely. These cases were mostly for locomotives, either railway locomotives or road steam wagons.
context_section_description: To avoid the problem of exposed fire-tubes above the water level, the submerged multi-tube boiler may be used. The upper boiler shell is extended upwards in an annular ring, so as to always maintain the whole length of the tubes submerged. Used in steam wagons and similar, where the water-level may be disturbed as the vehicle climbs a hill.
  The relatively rare Fowler steam wagons used a boiler of this form. The main barrel of the boiler contained a nest of curved firetubes between the stayless firebox and a large open space that formed a smokebox containing a five-turn spiral tube superheater. Both tubeplates were domed inwards, making them strong enough to not require staying. The firetubes were curved to 'cause eddies in the hot gases as they rise', to allow for free expansion with heat and also to allow a perpendicular joint between tube and tubeplate.
  An external belt of a channel plate riveted around the outside of the shell at the level of the upper tubeplate formed an additional steam and water space, linked below the water level by drilled holes through the shell. The boiler's operating water level was always maintained within this belt space, keeping the tubes entirely submerged. Drawbacks to this system were that the area of the water surface was reduced, leading to both an increased risk of priming and also the need to carefully maintain the boiler's water level; the ratio of volume to height becoming smaller in the belt region, a relatively small change in water volume produces a large change in level.
  A similar approach may be seen as the upper bulge around the vertical boiler of the reconstructed GWR railmotor.
  This design has also been suggested for model engineering use. In this case the belt was formed inside the boiler shell, with a tubeplate of reduced diameter set inside it.
caption: Submerged tube boiler
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