HP to Lb/hr Conversion for Boiler
HP to Lb/hr Conversion for Boiler
(OP)
It has been explained to me that to determine the steam mass flowrate (lb/hr) of a boiler you simply multiply the boiler HP by 34.5. However, no one has been able to provide me with the rational behind this conversion. Can anyone shed any light on this matter?





RE: HP to Lb/hr Conversion for Boiler
IE, it is based on a fixed pressure, fixed temperature, and wouldn't necessarily match the flow rates of your boiler at whatever pressure it operates at.
RE: HP to Lb/hr Conversion for Boiler
At the Centennial Exposition in Philadelphia in 1876 a boiler horsepower was taken as the evaporation of 30 lb of water per hour into steam, at a gage pressure of 70 psi with a feedwater temperature of 100*F. This was the weight of steam used, at that time, by a simple steam engine in producing 1 hp when the steam pressure was 70 PSI. This corresponds to the evaporation of 34.5 lb of water into steam, from and at 212*F per hour, and consequently at atmospheric pressure of 14.7 psia, and is known as the 'commercial rating' as adopted by the American Society Of Mechanical Engineers."
From "Elementary Steam Power Engineering" by Edgar MacNaughton. Copyright 1923