Understanding Pounds per foot-second to Centipoises Conversion
A pound per foot-second (lb/(ft-s)) is the US customary unit of dynamic (absolute) viscosity, mass flux resistance per unit velocity gradient. A centipoise (cP) is the CGS-based practical viscosity unit, with water near 1 cP at 20 degC. Process and lubrication engineers convert lb/(ft-s) into cP to compare imperial pipe-flow figures against the centipoise values on fluid data sheets.
Conversion Formula
To convert pounds per foot-second to centipoises, multiply by this factor:
Step-by-Step Example
Convert 25 pounds per foot-second to centipoises.
How to Convert Pounds per foot-second to Centipoises
Use the fixed conversion factor to turn any lb/(ft-s) figure into cP.
- Start with your value: Note the measurement in pounds per foot-second (lb/(ft-s)) that you want to convert.
- Apply the factor: Multiply that value by 1488.16, because 1 lb/(ft-s) = 1488.16 cP.
- Read the result: The product is the equivalent quantity expressed in centipoises (cP).
- Worked result: For 25 lb/(ft-s), calculate 25 x 1488.16 = 37204.1 cP.
pounds per foot-second to centipoises conversion table
| pounds per foot-second (lb/(ft-s)) | centipoises (cP) |
|---|---|
| 0 | 0 |
| 1 | 1488.164 |
| 2 | 2976.328 |
| 3 | 4464.492 |
| 4 | 5952.656 |
| 5 | 7440.82 |
| 6 | 8928.984 |
| 7 | 10417.15 |
| 8 | 11905.31 |
| 9 | 13393.48 |
| 10 | 14881.64 |
| 15 | 22322.46 |
| 20 | 29763.28 |
| 25 | 37204.1 |
| 30 | 44644.92 |
| 40 | 59526.56 |
| 50 | 74408.2 |
| 60 | 89289.84 |
| 70 | 104171.5 |
| 80 | 119053.1 |
| 90 | 133934.8 |
| 100 | 148816.4 |
| 150 | 223224.6 |
| 200 | 297632.8 |
| 250 | 372041 |
| 300 | 446449.2 |
| 400 | 595265.6 |
| 500 | 744082 |
| 600 | 892898.4 |
| 700 | 1041715 |
| 800 | 1190531 |
| 900 | 1339348 |
| 1000 | 1488164 |
| 2000 | 2976328 |
| 3000 | 4464492 |
| 4000 | 5952656 |
| 5000 | 7440820 |
| 10000 | 14881640 |
| 25000 | 37204100 |
| 50000 | 74408200 |
| 100000 | 148816400 |
| 250000 | 372041000 |
| 500000 | 744082000 |
| 1000000 | 1488164000 |
What is the pound per foot-second?
The pound per foot-second (lb/(ft·s)) is a unit of dynamic (absolute) viscosity in the English absolute (mass-based) system, where the pound is treated as a unit of mass (pound-mass). It is the FPS analogue of the poise, which is the gram per centimetre-second.
Definition
One pound per foot-second is the viscosity of mass one pound-mass flowing through one foot per second:
The exact value comes from and , giving . This is the pound-mass form and must not be confused with the gravitational pound-force-second per square foot, which is about 32.174 times larger.
Origin and History
This unit arises from the English absolute (or "poundal") system of mechanics, in which mass is the base quantity and force is the derived poundal. It appears in older engineering and chemical-engineering literature, particularly British texts, as a direct mass-based counterpart to the CGS poise.
Law and Notable Facts
It is not an SI unit. A useful relationship: , and the difference between this mass-based unit and the force-based lbf·s/ft² is exactly the standard gravitational conversion factor (the ratio of pound-force to poundal).
Real-World Examples and Conversions
Water at 20 °C () is about . A fluid of is roughly as viscous as light honey. Motor oil around is about .
What is the centipoise?
The centipoise (cP) is a CGS unit of dynamic (absolute) viscosity, equal to one hundredth of a poise. It is the most widely used practical viscosity unit in industry because water at about 20 °C has a viscosity of very nearly 1 cP.
Definition
One centipoise equals one hundredth of a poise, which in SI units is exactly one millipascal-second:
Since (the poise being defined as ), the centipoise is of that, i.e. exactly. The unit is dimensionally mass per length per time.
Origin and History
The poise is named after the French physician and physiologist Jean Léonard Marie Poiseuille (1797–1869), who studied the flow of liquids (blood) through narrow tubes and formulated what became the Hagen–Poiseuille law. The centipoise arose as a convenient submultiple because water conveniently sits near 1 cP, making comparisons intuitive.
Law and Notable Facts
The centipoise is a CGS-derived unit and is not part of the SI, which prefers the pascal-second (Pa·s) or millipascal-second (mPa·s). Because exactly, conversion between the everyday industrial unit and the SI unit requires no arithmetic beyond a change of name — a coincidence that has helped the centipoise survive.
Real-World Examples and Conversions
Water at 20 °C is about 1.002 cP. Whole milk is roughly 3 cP, olive oil around 60–80 cP, and honey near 2,000–10,000 cP. SAE 30 motor oil at 20 °C is on the order of 200 cP. To convert, .
Frequently Asked Questions
What is the formula to convert pounds per foot-second to centipoises?
Multiply the value in lb/(ft-s) by 1488.16 to get cP. For example, 25 lb/(ft-s) equal 37204.1 cP.
How many centipoises are in one pound per foot-second?
There are 1488.16 cP in a single lb/(ft-s), so the value in cP is always smaller when the factor is less than one.
How do I convert centipoises back to pounds per foot-second?
Reverse the operation by multiplying cP by 0.000671969, since 1 cP = 0.000671969 lb/(ft-s).
What does 100 pounds per foot-second equal in centipoises?
Multiplying gives 100 x 1488.16 = 148816 cP.
When is this lb/(ft-s) to cP conversion used?
Process and lubrication engineers convert lb/(ft-s) into cP to compare imperial pipe-flow figures against the centipoise values on fluid data sheets.
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Complete pounds per foot-second conversion table
| Unit | Result |
|---|---|
| pascal-seconds (Pa-s) | 1.488164 Pa-s |
| millipascal-seconds (mPa-s) | 1488.164 mPa-s |
| poises (P) | 14.88164 P |
| centipoises (cP) | 1488.164 cP |
| pound-force-seconds per square foot (lbf-s/ft2) | 0.03108095 lbf-s/ft2 |