Select steam flow or boiler heat output, then enter the displayed input. The default factor is 34.5 lb/hr per boiler horsepower for evaporation from and at 212°F at atmospheric pressure. Thermal kW uses 1 boiler horsepower ≈ 9.8095 kW.
Boiler HP to Lbs/Hr Formula
The following formula is used to calculate the steam production in pounds per hour for a given boiler horsepower.
Variables:
- L is the steam production in pounds per hour (Lbs/Hr)
- HP is the boiler horsepower
- F is the evaporation factor in lb/hr per boiler horsepower (default 34.5, from and at 212°F at atmospheric pressure)
To calculate the steam production in pounds per hour, multiply the boiler horsepower by the factor (typically 34.5).
| Boiler HP | Steam Flow (lb/hr) | Steam Flow (kg/hr) |
|---|---|---|
| 5 | 172.500 | 78.245 |
| 10 | 345.000 | 156.489 |
| 15 | 517.500 | 234.734 |
| 20 | 690.000 | 312.979 |
| 25 | 862.500 | 391.223 |
| 30 | 1035.000 | 469.468 |
| 40 | 1380.000 | 625.957 |
| 50 | 1725.000 | 782.447 |
| 60 | 2070.000 | 938.936 |
| 75 | 2587.500 | 1173.670 |
| 100 | 3450.000 | 1564.894 |
| 125 | 4312.500 | 1956.117 |
| 150 | 5175.000 | 2347.341 |
| 200 | 6900.000 | 3129.787 |
| 250 | 8625.000 | 3912.234 |
| 300 | 10350.000 | 4694.681 |
| 400 | 13800.000 | 6259.575 |
| 500 | 17250.000 | 7824.468 |
| 750 | 25875.000 | 11736.703 |
| 1000 | 34500.000 | 15648.937 |
| * Rounded to 3 decimals. Uses default boiler factor: 1 HP = 34.5 lb/hr ≈ 15.649 kg/hr (1 lb = 0.45359237 kg; standard evaporation from and at 212°F at atmospheric pressure). | ||
What is Boiler Horsepower?
Boiler horsepower is a unit of measurement used to express the power output of a steam boiler. One boiler horsepower corresponds to evaporating 34.5 pounds of water per hour from water at 212°F into steam at 212°F at atmospheric pressure, approximately 9.8095 kW of heat output. Actual evaporation depends on feedwater and steam conditions; mechanical horsepower is a different unit. This unit is commonly used in the steam generation industry to specify the capacity of boilers and to compare the performance of different boilers. A boiler horsepower rating expresses thermal capacity; it does not by itself determine efficiency or actual steam output.
How to Calculate Boiler HP to Lbs/Hr?
The following steps outline how to calculate the steam production in pounds per hour from boiler horsepower.
- First, determine the boiler horsepower (HP).
- Next, use 34.5 lb/hr per boiler horsepower for standard conditions, or open Conversion factor and enter a supported factor for your operating conditions.
- Next, calculate the steam production using the formula L = HP * F.
- Finally, calculate the steam production in pounds per hour (Lbs/Hr).
- After inserting the values and calculating the result, check your answer with the calculator above.
Example Problem :
Use the following variables as an example problem to test your knowledge.
Boiler Horsepower (HP) = 10
Factor (F) = 34.5
