page_title: Sentinel boiler
section_title: Firebox shape
hierarchical_section_title: Sentinel boiler / Description / Firebox shape
caption_attribution_description: Sentinel boiler, inner firebox shell. Later pattern, with a corrugated shell and the water-tubes arranged in a spiral.
context_page_description: The Sentinel boiler was a design of vertical boiler, fitted to the numerous steam waggons built by the Sentinel Waggon Works.
  The boiler was carefully designed for use in a steam wagon: it was compact, easy to handle whilst driving, and its maintenance features recognised the problems of poor feedwater quality and the need for it to be maintained by a small operator, rather than a major locomotive works.
  Although this design was used in most of Sentinel's products, they also produced larger boilers of quite different types for their railway locomotives.
context_section_description: Sentinel's best-known flue design was the square-section, but at one time they also used a circular corrugated design, with the water-tubes arranged in a spiral. Manufacture of these was sub-contracted to the well-known boilermakers Galloway of Manchester. When Galloway closed in 1932, Sentinel switched back to their square pattern.
caption: Inner firebox of the later spiral design
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