Dynamic viscosity is a measure of a fluid's internal resistance to flow when subjected to an external force. In engineering, converting between the CGS (centimeter-gram-second) system and the Imperial system is a common requirement for fluid mechanics calculations.
Poise (P): Named after Jean Léonard Marie Poiseuille, the Poise is the CGS unit of dynamic viscosity. It is defined as \(1 \text{ P} = 0.1 \text{ Pa}\cdot\text{s}\). It is frequently used in chemistry and materials science to describe the thickness of liquids.
Pound per foot-second (lb/(ft·s)): This is the Imperial unit of dynamic viscosity. It is often utilized in legacy industrial piping systems and mechanical engineering specifications in the United States.
The conversion factor is derived from the relationship between the base units of mass, length, and time. To convert from Poise to lb/(ft·s), we use the factor \(0.06719689496587741\).
Poise to Pound per foot-second Conversion Reference Table
Poise (P)
Pound per foot-second (lb/(ft·s))
0.1
0.0067
0.5
0.0336
1.0
0.0672
2.0
0.1344
5.0
0.336
10.0
0.672
20.0
1.3439
50.0
3.3598
100.0
6.7197
500.0
33.5984
1000.0
67.1969
Conversion Example
To convert a dynamic viscosity value from Poise (P) to pound per foot-second (lb/(ft·s)), multiply the value in Poise by the conversion factor of \(0.06719689496587741\).
While the SI unit Pascal-second (Pa·s) is preferred, the Poise remains common in industrial standards, particularly for lubricants and polymer processing, due to historical data sets and legacy instrumentation calibration.
Yes, 1 Poise is equal to 100 Centipoise (cP). Centipoise is more commonly used in practical applications because the viscosity of water at room temperature is approximately 1 cP.
"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)