Dynamic viscosity, also known as absolute viscosity, measures a fluid's internal resistance to flow when subjected to an external shear stress. In engineering, converting between the International System of Units (SI) and the Imperial system is a frequent requirement for cross-border technical documentation.
Pascal-second (Pa·s): The SI unit of dynamic viscosity. It is defined as the viscosity of a fluid in which a stress of one pascal produces a velocity gradient of one meter per second per meter. It is equivalent to \(1 \text{ N} \cdot \text{s/m}^2\).
Pound per foot-second (lb/(ft·s)): A unit used primarily in the United States customary system. It represents the force in pounds-force required to maintain a velocity gradient in a fluid column.
Engineers often utilize the conversion factor \(1 \text{ Pa} \cdot \text{s} \approx 0.671969 \text{ lb/(ft} \cdot \text{s)}\) to ensure compatibility between global fluid dynamics models and legacy industrial specifications.
Pascal-second to Pound per foot-second Conversion Reference Table
Pascal-second (Pa·s)
Pound per foot-second (lb/(ft·s))
0.1
0.0672
0.5
0.336
1.0
0.672
2.0
1.3439
5.0
3.3598
10.0
6.7197
20.0
13.4394
50.0
33.5984
100.0
67.1969
500.0
335.9845
1000.0
671.9689
Conversion Example: 10 Pa·s to lb/(ft·s)
To convert a dynamic viscosity value from Pascal-seconds to pounds per foot-second, multiply the given value by the conversion factor of 0.6719689496587742.
Dynamic viscosity is critical for calculating Reynolds numbers, determining pressure drops in piping systems, and designing lubrication systems for machinery. It dictates how much energy is required to move a fluid through a conduit.
No. Centipoise (cP) is a common CGS unit where 1 cP = 0.001 Pa·s. The unit lb/(ft·s) is significantly larger than the centipoise, requiring a specific conversion factor to bridge the Imperial and SI systems.
"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)