Mass flow rate is a critical parameter in process engineering, representing the mass of a substance passing through a specific cross-section per unit of time. The two primary units used in industrial settings are the pound per hour (lb/h) and the kilogram per hour (kg/h).
Pound per hour (lb/h): A unit derived from the Imperial system, commonly used in the United States oil, gas, and HVAC industries.
Kilogram per hour (kg/h): The SI-derived unit for mass flow, utilized globally in scientific research, chemical processing, and international trade.
The conversion is based on the international avoirdupois pound, defined exactly as 0.45359237 kilograms. Therefore, the conversion factor for mass flow rate is defined by the equation \(1 \text{ lb/h} = 0.4535923716 \text{ kg/h}\).
Pound per hour to Kilogram per hour Conversion Reference Table
Pound per hour (lb/h)
Kilogram per hour (kg/h)
0.1
0.0454
0.5
0.2268
1.0
0.4536
2.0
0.9072
5.0
2.268
10.0
4.5359
20.0
9.0718
50.0
22.6796
100.0
45.3592
500.0
226.7962
1000.0
453.5924
Conversion Example
To convert a mass flow rate from lb/h to kg/h, multiply the value by the conversion factor of 0.4535923716. For example, to convert 10 lb/h:
The factor 0.4535923716 is derived from the international standard definition of the pound. In high-precision engineering, such as mass balance calculations for chemical reactors, using the full precision is necessary to prevent cumulative rounding errors.
While they measure the same physical quantity, industry standards often dictate the unit. US-based legacy systems typically require lb/h, while international projects and modern instrumentation usually default to SI units like kg/h.
"On fait la science avec des faits, comme on fait une maison avec des pierres ; mais une accumulation de faits n'est pas plus une science qu'un tas de pierres n'est une maison." "Science is built up of facts, as a house is built of stones; but an accumulation of facts is no more a science than a heap of stones is a house." — Henri Poincaré (French Mathematician, Theoretical Physicist & Mining Engineer)