Crawford’s Patent Model of Steam Boiler Furnace– ca 1849

Crawford’s Patent Model of Steam Boiler Furnace– ca 1849

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This model was filed with the application to the U.S. Patent Office for Patent Number 7,051 issued to Benjamin Crawford of Allegheny, Pennsylvania on January 29, 1850. The patent was for improvements in air heaters and steam blowers for a steam boiler furnace. Boilers of this type were commonly used on river steamboats. The model represents a pair of boilers located side by side and seen as the two parallel, horizontal cylinders on the same level. The ash pit doors, firebox doors, flues and chimneys are shown at the end. One of the key elements of Crawford's patent was a combustion air heater in the form of a heat exchanger that passed incoming air through pipes surrounded by hot steam from the exhaust of the engine. This is seen as the smaller horizontal cylinder located between and above the boilers. The heated air was channeled through pipes leading down to the ash pits. The routing of these pipes was through the flues of the boilers, and this added considerably to the temperature of the air. To increase the velocity of this air, Crawford's design fed steam under pressure into the ends of these pipes. The design additionally improved efficiency of combustion by introducing jets of pressurized steam into the fire boxes and chimneys. The steam was conducted via another set of pipes. At the ends of these pipes were fixed nozzles that rotated as a result of the steam pressure. Crawford claimed these increased the mixing of combustion gases in the firebox and increased ability of the gases passing up the chimney to provide a strong draft through the boiler furnace.
The patent model is constructed of sheet metal. The key elements of the patent are illustrated in the model to include the various pipes conducting air and steam into the ash pit, combustion chamber, and flues. Doors give access to the ash pits and combustion chambers. Diagrams showing the complete design of the patent can be found in the patent document online at the United States Patent and Trademark Office website,
Object Name
boiler, steam, model
patent model, boiler, steam
date made
patent date
Crawford, Benjamin
place made
United States: Pennsylvania
associated place
United States: Pennsylvania, Allegheny
overall: 9 in x 17 in x 12 in; 22.86 cm x 43.18 cm x 30.48 cm
ID Number
catalog number
accession number
patent number
Patent Models
Steam Engines
See more items in
Work and Industry: Mechanical and Civil Engineering
Patent Models
Engineering, Building, and Architecture
Power Machinery
Exhibition Location
National Museum of American History
Data Source
National Museum of American History
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