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# Boiler Horsepower

## Boiler horsepower vs. heat transfer area.

Boiler horsepower - a power unit from the 19th-20th centuries - was  used to rate the capacity of a boiler to deliver steam to steam engines.

A common definition of one boiler horsepower is the amount of energy required to produce 34.5 pounds (15.65 kg) of steam per hour at pressure and temperature 0 psig (0 bar) and 212oF (100oC) - with feed water at pressure 0 psig and temperature 212oF. One boiler horsepower is about 33479 Btu per hour (about 9812 watts, 8437 kcal/hr).

Boiler horsepower was used in USA, Australia, and New Zealand and have been calculated in different ways.

PBoHP = A / k                                   (1)

where

PBoHP = boiler horsepower

A = heat transfer area (ft2)

k = standard area (ft2) - in New Zealand it was common to use 17, in US it was common to use 10 before year 1900 - and more common to use 5 after

Be aware that the a boiler horsepower is not the commonly accepted 550 ft lbf/s and the generally accepted conversion factor of 746 Watts = 1 horsepower does not apply.

### Boiler Conversion Ratios

 from multiply to sq.ft. EDR steam 240 Btu per hr. sq.ft. EDR water 160 Btu per hr. Boiler hp 33.5 MBtu per hr. Boiler hp 140 sq.ft. EDR steam Boiler hp 223 sq.ft. EDR water Boiler hp 34.5 lb. per hr. steam lb. per hr. steam 970 Btu per hr. to divide by above from

## Related Topics

• ### Thermodynamics

Thermodynamics of steam and condensate systems.

## Related Documents

• ### ASME - International Boiler and Pressure Vessel Code

The International Boiler and Pressure Vessel Code safety rules governing design, fabrication, and inspection of boilers and pressure vessels, and nuclear power plant components during construction.
• ### Boiler - Efficiency

Combustion gross and net calorific value.
• ### Boiler Capacities

Steam boilers output can be expressed in Boiler Horsepower, MBTU or in Pounds of Steam delivered per hour.
• ### Boilers - Classification

Classification of boilers according the ASME Boiler and Pressure Vessel Code.
• ### Pumps, Fans and Turbines - Horsepower

British Horse Power as used for pumps, fans and turbines - and how to convert to other units.
• ### Steam Boiler Rating vs. Feed Water Temperature

Boiler output vs. feed water temperature.

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## Citation

• The Engineering ToolBox (2008). Boiler Horsepower. [online] Available at: https://www.engineeringtoolbox.com/boiler-horsepower-d_1061.html [Accessed Day Month Year].

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12.8.9