What is the farmula of measuring Horse Power of a steam boiler by its heating surface?
*Boiler horsepower is used rating a boiler's capacity to deliver steam to a steam engine. The amount of energy needed to produce 34.5 pounds (15.65 kg) of steam, per hour, at a pressure and temperature of 0 Psig (0 bar) and 212 oF (100 oC), with feed water at 0 Psig and 212 oF. One boiler horsepower is about 33,479 Btu per hour (about 9,810 watts, 8430 Kcal/Hr). Boiler horsepower can be determined from the heat transfer area. PBoHP = A / 17 where, PBoHP = boiler horsepower A = heat transfer area (ft^2) *In a water-tube boiler there should be from 10 to 12 square feet of heating surface for one horse-power; in a tubular boiler 14 to 18 square feet of heating surface for one horse-power; in a flue boiler 8 to 12 square feet of heating surface for one horse-power; a plain cylinder boiler should have from 6 to 10 square feet of heating surface for one horse-power; a locomotive boiler should have 12 to 16 square feet of heating surface for one horsepower; a vertical boiler should have from 15 to 20 square feet of heating surface for one horse-power. When considering the heating surface of a boiler, a vertical or upright surface has only one-half the evaporative value of a horizontal surface above the flamet; that is, the sides of a locomotive fire-box are only half as effective per square foot as the flat top of the box. In flues and tubes, the effective surface, measured on the circumference, is 1% times the diameter.
